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Hacking the atmosphere: Geoengineering gets a reality check (MIT Technology Review)

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technologyreview.com

Original article

James Temple

June 17, 2026

Jim Franke pulls away the cover page of a presentation on the wraparound desk in his office, revealing an illustration of an odd-­looking aircraft with massive wings stretching out from a stubby fuselage.

The uncrewed plane is soaring thousands of meters higher than commercial jets fly—so high you can see the curvature of the Earth. It’s precisely the type of aircraft one would need to begin artificially cooling the planet. Those outsize wings would keep the plane and its payload aloft in the stratosphere, about a dozen miles (or 20 kilometers) above the surface, where the air is much thinner—as little as 5% the density near the ground. Once at altitude, the plane would release materials that could, after a few steps of chemistry, reflect sunlight back into space.

“If you want to get to 20 kilometers in the near term, this is probably the best bet,” says Franke, a research assistant professor at the University of Chicago.

Franke is one of a small but growing cohort of scientists focused on the engineering challenges associated with solar geoengineering, the controversial idea that we could deliberately intervene in the climate system to counteract global warming.

The concept came from volcanoes. Massive eruptions in the past have reduced temperatures worldwide by blasting sulfur dioxide and other compounds into the stratosphere, where they convert into sunlight-scattering particles. Hundreds of studies in recent decades have suggested that a human attempt to mimic this mechanism would work quickly and efficiently—at least within the confines of climate models.

But these computer simulations are approximations of how the real world works. They gloss over numerous challenges. Like the fact that aircraft capable of carrying the necessary loads to the necessary altitudes don’t exist. Or that we don’t know for sure how to release material so that most of it turns into tiny reflective aerosols instead of, say, clumping together and falling out of the sky. Or even what specific substance we would want to load onto an aircraft, given open questions about safety, cost, and effectiveness. 

Amid these compounding unknowns, more and more research on solar geoengineering is moving beyond computer simulations, delving into the detailed design and practical engineering work that would be needed before we could carry out a campaign to dial down temperatures. The tasks required range from inventing high-altitude aircraft to mastering the precise chemistry and delivery mechanisms for dispersing materials to building out the monitoring infrastructure that we’ll need in order to know if any of it actually works.

The question of whether we should geoengineer the planet has no clear-cut answer. It might save millions of lives by reducing the dangers of catastrophic heat waves, floods, droughts, and famines. But many fear it’s too dangerous to even consider, much less seriously study, arguing that we can’t possibly predict the spiraling consequences of manipulating such large, complex, interconnected planetary systems. 

Critics argue that the building momentum in this phase of research will make it ever more likely that someone, somewhere in the world, will eventually pull the trigger on geoengineering, no matter the remaining unknowns or the dangers for certain parts of the world.  

“I do think it’s very dangerous because of what we know about science and technology,” says Jennie Stephens, a professor of climate justice at Maynooth University in Ireland. “The more investment that’s made, the further the advances, the more likely it is that it will be deployed.”

But proponents of this practical research argue that playing out how we’d mount a solar geoengineering program will improve our understanding of the potential benefits and risks, helping to ensure that if anyone does try to tweak the climate, they might at least do so in an informed and potentially safer way.

David Keith
The Climate Systems Engineering Initiative (CSEi) at the University of Chicago formally launched in 2024 under the leadership of the prominent geoengineering researcher David Keith.

It’s still very much a niche field. Much of the work now underway is happening at the Climate Systems Engineering Initiative (CSEi) at the University of Chicago, which formally launched in 2024 under the leadership of the prominent geoengineering researcher David Keith. 

Franke, a professional engineer before earning his doctorate in geosciences, is overseeing a series of overlapping research projects and collaborations aimed at resolving many of the engineering uncertainties. That includes working out the designs now on his desk—renderings of the type of aircraft that could be used in the initial phase of a geoengineering program. 

Franke argues that more computer simulations are simply not going to answer the big remaining questions in the field, including the most compelling one: the “boogeyman” of what could go wrong. 

“I’m kind of personally skeptical that additional model development or more simulations are going to satisfactorily resolve those things,” he says. “And so I’m not really that interested in turning the crank on more models.”

For Franke, it’s time for the next step: “We’re interested in seeing how you’d actually do this thing if you wanted to do it.”

What we don’t know

Solar geoengineering is often portrayed as a relatively cheap and easy fix for climate change. But as researchers take a harder look at the nuts and bolts, they’re finding considerable uncertainties, missing tools, and unbuilt infrastructure.

None of that may be a showstopper, but we’ll need time and money to develop the components necessary to implement even the early stages of a solar geoengineering program. What this research is about, at its core, is not actually launching something, but figuring out what it would take to do so. 

A young San Francisco nonprofit, Reflective, recently worked with scientists in the field to figure out just how much we still don’t know.

The process began by outlining what the organization, which pools money from donors to fund geoengineering studies, describes as a “well-managed, moderate” scenario: In 2035, some nation or group of nations begins a small-scale geoengineering deployment, spraying an equal amount of sulfur dioxide or hydrogen sulfide—gases that should convert into reflective aerosols in the stratosphere—near both the North and South Poles. The initial program would release enough material to reduce temperatures by about 0.1 °C, shaving off a fraction of the roughly 1.4 °C of worldwide warming that’s occurred since the start of the industrial era.

The poles figure prominently in this and other early-stage geoengineering scenarios, for a simple reason: The stratosphere starts as low as seven kilometers there—as opposed to around 18 to 20 kilometers at the equator. That makes it easier to reach, enabling existing aircraft, with some modifications, to carry sizable payloads up there. 

The wrinkle is that the cooling effect would be more pronounced in the northernmost and southernmost latitudes. That’s because, among other complicated mechanisms, higher temperatures in the tropical stratosphere would mostly prevent aerosols released around the poles from drifting toward the equator. So deploying geoengineering in those areas would likely have milder effects on the hotter and poorer nations around the tropics, which are also some of the areas most vulnerable to climate change.

To cool the world evenly—and fairly—you’d eventually want to add flights closer to the equator. Over the following decade or so, under Reflective’s scenario, the program would scale up, shift to novel aircraft flying above the subtropics, and release enough material to achieve global cooling of 0.5 °C. 

The question the researchers then examined was: If we wanted to carry out such a scenario, what would we still need to do to pull it off? 

Quite a bit, it turns out. Earlier this year, Reflective published its SAI Uncertainty Database (SAI stands for “stratospheric aerosol injection”), highlighting a variety of scientific unknowns and six engineering obstacles.

Among them: sorting out how hard or expensive it would be to retrofit existing aircraft to carry out the early stages of the project. Deploying at the poles could also require constructing new airports, establishing new shipping lanes or railways to transport supplies, and building facilities that could process raw materials—by, for example, combusting elemental sulfur to produce sulfur dioxide.

We would also need to build more instruments and send them up to the stratosphere aboard balloons, drones, or other aircraft to observe the baseline chemistry, reflectivity, and distribution of compounds there—and to track what changed once new materials were released.

Finally, the main satellites that observe the stratosphere from space are set to go out of commission in the coming years, creating the risk of an “imminent data desert,” as a 2025 paper in the Bulletin of the American Meteorological Society warned. Several new instruments are in development or available for launch, but there could be a gap in observations at a point where we’d want to have a clear picture of the baseline conditions, Reflective notes.

Dakota Gruener, the chief executive officer of the nonprofit, stresses that the organization isn’t advocating the use of solar geoengineering. But she says it’s important for the field to begin addressing engineering uncertainties now because it stress-tests the assumptions in climate models. It helps us determine whether the scenarios explored in silico are feasible in the real world.

It’s also important to do this, she says, because it may take a long time to resolve all these unknowns while the climate grows steadily warmer. “If we aren’t putting adequate attention to them now, we might be caught flat-footed,” Gruener told MIT Technology Review.

A 2024 analysis in the journal Earth’s Future highlighted just how expensive and time-consuming it might be to develop the aircraft and infrastructure required for an initial deployment. The study explored what it would take for a geoengineering program around the poles, capable of reducing temperatures by 2 °C in the northernmost and southernmost parts of the planet, to be up and running by 2040. The conclusion: It could require at least a decade of work and a $35 billion investment. 

Wake Smith, a research fellow at Harvard and lead author of the study, also says that researchers need to move forward with engineering studies now, because the urge to use the technology will likely grow stronger as climate change becomes increasingly catastrophic.

“The risk I worry about is needing it before we understand it and therefore doing it badly,” he says, later adding: “The sooner we get going with it, the better decisions we’ll be able to make a few decades hence in terms of whether to do it, how to do it, when to do it.”

A novel aircraft

The aircraft pictured on Franke’s desk, which is still just a concept, could reach just beyond the threshold of the stratosphere above the tropics when fully loaded. A fleet of 270 of them could disperse about a million metric tons of material per year, enough to ease global surface temperatures by about 0.26 °C. 

The CSEi outsourced the work of designing it to John Langford, a well-known aeronautical engineer and entrepreneur. Langford’s company, Electra.aero, had previously collaborated with the MIT Department of Aeronautics and Astronautics to develop autonomous, solar-powered aircraft that could carry out extended scientific missions in the stratosphere. He is now spinning out a new business, Iris Aero, to produce those planes, which are assembled from a single, continuous wing covered in solar panels and suspended above a tiny fuselage.

Langford expects the solar plane to find its main initial commercial applications in wildfire monitoring and forecasting. But by swapping in a different set of instruments, it could be used to monitor how materials dispersed in the stratosphere might alter conditions there, he says.

The novel aircraft is a variation on the observational plane, with the added space and thrust necessary to carry these materials to the stratosphere and release them. It has a wider wingspan and swaps out those solar panels for a pair of Rolls-Royce AE 3007 engines.

The aircraft would also include a detachable tank that would function something like a trailer on a semi. This would make it possible to load materials between flights and prevent any damage to the plane itself from those materials, some of which are corrosive, Langford says. 

He says he and his team have completed the initial designs and are now doing more detailed engineering and cost analyses. They intend to publish the findings when the effort is complete. 

“We’d love to build a prototype of such an airplane and feel we could do so relatively quickly,” Langford says. “But that all depends on what David’s group wants to do.”

The program

David Keith’s group, CSEi, is still coming together.

The University of Chicago unveiled the research initiative in 2024 and has committed to hiring 10 additional faculty members to advance scientific understanding of various forms of geoengineering and explore the thorny questions related to policy, ethics, and governance. It had hired two of them as of press time.

The university saw an opportunity to step up as a leader in a field that wasn’t getting adequate academic attention despite its potential to address the dangers of climate change, says Michael Greenstone, a climate economist and the founding director of the university’s Institute for Climate and Sustainable Growth.

“Universities, as a whole, were committing academic malpractice by not investigating the technical, the social, the political, and the even kind of humanist elements of geoengineering,” Greenstone says.

He helped recruit Keith to lead the initiative. 

Keith, 62, previously spent nearly 13 years as a professor of applied physics and public policy at Harvard, where he led the establishment of the university’s Solar Geoengineering Research Program. More famously, he strove to carry out what could have been the first solar geoengineering experiment to release material in the stratosphere, known as SCoPEx. But after years of work and multiple delays, the research team finally scrapped the project in early 2024, following mounting criticism from environmental and Indigenous groups and the eventual intervention of the Swedish government.

Keith has long argued that researchers should seriously study geoengineering because it might substantially reduce the dangers of climate change, alleviating death, destruction, and suffering on massive scales.

He says that the overarching goal of the Chicago initiative is to expand the field by bringing together “enough independent professors and other research professionals” to “build a community around climate engineering as a broad field of inquiry.”

“Solar geoengineering certainly has complex and potentially dangerous political consequences, but so do a host of other emerging ideas and technologies.” David Keith, geoengineering researcher

“The University of Chicago was the first big university to try and build this as a field in a serious way, to make it not about one person,” he tells me. “It’s a giant commitment.”

Keith himself has become a divisive figure, the face of geoengineering to some. He says he now wants to help build a larger, sustainable research program that will outlive his involvement. He told the administrators that he shouldn’t run the program for more than five years.

“It’s important to have a generational handover,” he says, adding: “I think it’s really important that this not be ‘the David Keith Show.’”

The CSEi researchers are now exploring nearly every engineering challenge that Reflective highlighted in its analysis. In addition to the work on novel aircraft and in situ observations, the group is designing small “cube” satellites with optical sensors optimized for observing the stratosphere. It is also studying which materials might prove most practical to ship to the stratosphere and how best to release them.

The goal is “producing public information which can be independently assessed, critically assessed, so policymakers can understand more about what’s possible and not,” Keith says.

Normalizing a dangerous idea

The debate around solar geoengineering is quickly moving beyond the academic and theoretical realm. A handful of startups, some more serious than others, have begun testing technologies that could one day be used to cool the planet. 

Yet to critics, solar geoengineering is the peak of techno-solutionism, affixing a high-tech Band-Aid to a global crisis caused by earlier technologies instead of addressing the root cause. Further, they argue that there’s no way to deploy or govern it in a globally equitable way, because any use of it will prove more advantageous to some regions than others. 

Even if solar geoengineering succeeded in reducing the average global temperature by 1 °C or so, that would mean very different things in different regions.

It could keep farmers prosperous and cities safe across, say, much of the US and the world’s temperate zones. But the lower temperature might be too cool for Russia to boost its agricultural productivity, while it might still be too hot for subsistence farming in northern Africa. 

Some studies also suggest that high levels of solar geoengineering could create new dangers in some regions, potentially altering monsoon rains, decreasing agricultural output, shifting the range of infectious diseases, and more. 

These complications raise a long list of thorny and divisive ethical questions. Even if solar geoengineering produced better conditions across most of the planet relative to a world with unchecked climate change, would it still be acceptable if it unleashed deadly famines or floods in a few regions? What kind of global consensus should be required to decide it’s okay to deploy it? And how should we determine where to set the planet’s temperature—and when, if ever, to shut the technology off?

Stephens argues that the answers, like so much else in the world, will come down to wealth and power. Countries, corporations, or even wealthy individuals with the resources to deploy such a system would have every incentive to tune it for their optimal benefit, no matter what it might mean for others. 

“It will be certain people who have a lot of wealth and power deciding when and how, and who should benefit and who will get screwed,” she says. “That’s the fundamental reason I think any advance in this technology is so dangerous.”

Duncan McLaren, an environmental researcher and political scientist, argues that the shift into practical engineering studies demands more oversight of the research field.  

For many critics of outdoor experiments like SCoPEx, he explains, the major concern wasn’t the environmental or safety risks, which were minimal; the issue was the normalization of a concept that could reduce pressures to cut greenhouse-­gas emissions. 

He says that any advance in research—whether it’s on paper, in the lab, or in the stratosphere—raises a similar risk: undermining progress on climate action by allowing the fossil-fuel sector and other business interests to say there’s an easier solution in development that doesn’t require overhauling our energy systems. A policy paper that the Texas Conservative Coalition Research Institute released in March advanced this very argument, citing the far lower costs of solar geoengineering relative to the “staggering costs” of a “forced transition.” 

Given this so-called moral hazard risk, design and engineering work should demand the same level of scientific supervision that outdoor experiments do, including ethical review, risk assessments, and public engagement, McLaren says.

“It ought to be more onerous,” he says. “There ought to be more barriers to researchers saying they want to do this.”

“The next ethical step”

Keith pushes back forcefully on that assertion, condemning as “profoundly illiberal” the idea that we should regulate open academic research posing no physical risks. 

“Solar geoengineering certainly has complex and potentially dangerous political consequences, but so do a host of other emerging ideas and technologies,” he said in an email. “The best chance to manage these challenges is to debate them openly and freely.”

Keith is all for keeping solar geoengineering technology in the public domain, and he agrees that the first line of climate defense must be rapid and deep reduction of greenhouse-gas emissions. But the world has made little progress in cutting climate pollution, carbon dioxide can persist for thousands of years in the atmosphere, and the planet is heating up fast. So, he argues, we may need to pursue other measures to temper the growing threats.

The bar for restricting research in this field should be “very high,” he says, given the potential promise of the technology. 

After visiting flood-devastated villages in Bangladesh, Keith underscored this point in an interview with the director of Plan C for Civilization, a recent documentary that profiles his work. “I think people have to take the next ethical step,” he said. “Because if you are really going to withhold access to and knowledge of a technology that could potentially save enormous numbers of lives—real lives, people we’ve met in the last few days—you’ve got to be very confident that that technology is going to be misused.”

The particles

Mingyi Wang, an assistant professor at the University of Chicago, leads me down the hall to a square, white lab room in the Henry Hinds Laboratory for Geophysical Sciences.

He pulls open the doors to a gray Haier biomedical freezer just inside the entrance, revealing a transparent flow tube hanging vertically and tapering at the bottom.

It’s a miniature stratosphere, chilled below −50 °C and filled with the same mix  of oxygen, nitrogen, and other air molecules you’d find 20 or so kilometers above us. A series of Teflon and stainless-­steel tubes run into the vessel, allowing Wang and his team to add various gases or particles and observe how they react.

Wang is an atmospheric scientist who studies how aerosols form, and he is now exploring what materials might be the most effective for reducing temperatures. 

an aircraft shown from above flying over the clouds
This rendering illustrates the type of high-altitude aircraft that could one day be used to deliver Earth-cooling material into the stratosphere.

Most modeling experiments focusing on solar geoengineering explore the impact of adding sulfuric acid to the stratosphere, because that’s what ultimately ends up there after a volcanic blast. 

But it would be costly and complicated to simply haul sulfuric acid up there and release it, because it’s heavy and sticky. So Wang and his team are conducting experiments in that chilly flow tube to determine what substances, including precursors to the acid, might do the best job of producing aerosols of the ideal size for reflecting away sunlight—and how best to prevent the materials from simply clumping together with existing particles and falling out of the stratosphere.

Wang, whom Keith refers to as a “young star,” has arrived at a novel solution to this problem, though he’s not ready to share the full details yet. He and his team are feeding the findings from their experiments into computer simulations of stratospheric plumes that they’ve developed. These, in turn, can be plugged into large-scale climate models to improve their simulation of smaller-scale effects—and thus enhance our understanding of stratospheric chemistry.

Wang says that it’s important to do this detailed research because until now, climate models simply assumed you’d wind up with the right aerosols of the right size. 

“Scientifically, we may understand it reasonably well, but on the engineering perspective—do we really know how to do it right?” he asks. “That’s a big question.” 

What’s next

As I began reporting on CSEi, I assumed that some of the engineering and design work would lead to new proposals for stratospheric experiments, picking up from where SCoPEx left off. 

Keith, though, insists he has no interest in reliving that experience, given the weight the experiment took on as the focal point for a broader societal debate over solar geoengineering. He doesn’t see any of the other “practical engineering” work at the initiative leading toward field experiments either, at least at this stage.

Much of the work, in fact, is focused on a step beyond that: exploring what it would take to start a geoengineering campaign, if a nation or group of them eventually decides to. Franke notes that we already have balloons and other aircraft that could get to the lower bounds of the stratosphere to release an experimental amount of, say, sulfur dioxide. 

“We’re thinking of it right now as: We’re trying to develop, we think, the tools should someone want to start doing SAI,” he says. 

He and Keith are quick to stress that the research group does not intend to actually build the physical hardware that would be needed to deploy solar geoengineering—not even the aircraft that Langford’s company is designing. 

Indeed, most of the researchers at the University of Chicago stress that they are not advocating for use of geoengineering; they’re doing the research to inform the public and policymakers about its benefits and risks.

But after decades closely studying the topic, Keith, at least, has evolved in his thinking on this point, and his public comments reflect that. 

“As a scientist, I think the evidence [indicates] that early deployment—careful, hemispherically balanced, slow, monitored early deployment—would have benefits that are higher than the risks,” he says. “I think that evidence is very strong.”

Keith adds that if there were somehow a global referendum on whether to start, he would vote yes. 

“I think that this field needs to stop being so ashamed of using the ‘deployment’ word,” he says. 

Factcheck: Trump’s false claims about the IPCC and ‘RCP8.5’ climate scenario (Carbon Brief)

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US president Donald Trump.

US president Donald Trump. Credit: Associated Press / Alamy Stock Photo

FACTCHECKS – Original post

Multiple Authors 

19.05.2026 | 5:22pm

Among a flurry of posts on social media last weekend, US president Donald Trump declared “good riddance” to a specific emissions scenario used in global climate projections.

The “RCP8.5” scenario, which envisages a future of very high carbon emissions, was “wrong, wrong, wrong”, the president wrote in block capitals.

This was “just admitted” by the UN’s “top climate committee”, he falsely claimed, referring to the Intergovernmental Panel on Climate Change (IPCC).

The post was quickly picked up by right-leaning media, amplifying Trump’s misrepresentation of emissions scenarios and the role of the IPCC.

His claim follows the publication of a new set of emissions scenarios that will feed into the next IPCC reports. 

While the new scenarios no longer include such high emissions as in RCP8.5, they also show it is “not possible” to limit global warming to 1.5C above pre-industrial levels without significant “overshoot”, one of the authors tells Carbon Brief.

Moreover, projections suggest that the world is still on course for between 2.5C and 3C of warming, another author says.

This level of warming was previously described as “catastrophic” by the UN.

In this factcheck, Carbon Brief looks at Trump’s comments, the debate around RCP8.5 and the “good” and “bad” news within the latest scenarios.

What did Trump say?

In the late evening of Saturday 16 May, Trump posted the following message on his Truth Social social-media platform:

Social media post by US president Donald Trump that says: "GOOD RIDDANCE! After 15 years of Dumocrats promising that “Climate Change” is going to destroy the Planet, the United Nations TOP Climate Committee just admitted that its own projections (RCP8.5) were WRONG! WRONG! WRONG! For far too long Climate Activism has been used by Dumocrats to scare Americans, push horrible Energy Polices, and fund BILLIONS into their bogus research programs. Unlike the Dumocrats, who use Climate Alarmism nonsense to push their GREEN NEW SCAM, my Administration will always be based on TRUTH, SCIENCE, and FACT! President DONALD J. TRUMP"

“Dumocrats” is a derogatory nickname for Democrat politicians, debuted by the president in a televised Fox News interview on Thursday 14 May, according to the Independent.

By “top climate committee”, the president was presumably referring to the IPCC, the UN body responsible for assessing science about human-caused climate change. 

However, the IPCC does not develop, control or own climate scenarios. Moreover, it has not published anything stating that any climate scenario is “wrong”. (For more, see: How is the IPCC involved?)

Nevertheless, right-leaning media outlets have reported on Trump’s comments, in many instances repeating his false assertion that the RCP8.5 climate scenario had been developed by the IPCC. 

The New York Post misleadingly claimed that the IPCC “had quietly adjusted” its framework of emission scenarios. The Daily Caller, a pro-Trump conspiratorial US outlet, adds its own falsehoods stating that “IPCC researchers revised their modelling approach last month, swapping the extreme pathway for seven alternative scenarios”. The climate-sceptic Australian claimed that scientists had “quietly scrapped the apocalyptic forecasts that have terrified policymakers and the public”.

With Fox News also covering Trump’s comments, along with an earlier article by the Times, much of the reporting around RCP8.5 in recent days has been driven by media controlled by the climate-sceptic mogul Rupert Murdoch.

It is not the first time the Trump administration has attacked RCP8.5. In an executive order  issued in May 2025 – entitled, “Restoring gold-standard science” – the White House included the climate scenario in a list of examples of how the previous government had “used or promoted scientific information in a highly misleading manner”.

Excerpt from White House executive order, saying: "Similarly, agencies have used Representative Concentration Pathway (RCP) scenario 8.5 to assess the potential effects of climate change in a “higher” warming scenario. RCP 8.5 is a worst-case scenario based on highly unlikely assumptions like end-of-century coal use exceeding estimates of recoverable coal reserves. Scientists have warned that presenting RCP 8.5 as a likely outcome is misleading."
Excerpt from White House executive order, issued in May 2025.

Federal agencies, it claimed, had been using RCP8.5 to “assess the potential effects of climate change in a higher warming scenario”, despite scientists warning that “presenting RCP8.5 as a likely outcome is misleading”.

The executive order came after Project 2025 – a policy wishlist for Trump’s second term published in 2023 by the Heritage Foundation, an influential rightwing, climate-sceptic thinktank in the US  – criticised the climate scenario.

The manifesto said a “day-one” priority for the new government should be to “eliminate” the US Environmental Protection Agency’s “use of unauthorised regulatory inputs”, such as “unrealistic climate scenarios, including those based on RCP8.5”.

What is RCP8.5?

Scientists use emissions scenarios to explore potential future climates, based on how global energy and land use could change in the decades to come. 

These scenarios are not predictions or forecasts of what will happen in the future. Therefore, Trump’s declaration that projections under RCP8.5 were “wrong, wrong, wrong” misrepresents the purpose of emissions scenarios.

Different modelling groups have produced thousands of different scenarios over the years. RCP8.5 was developed by scientists back in the early 2010s as one of a set of four consistent “representative concentration pathways”, or RCPs, for climate modellers to use. 

As their name suggests, the RCPs were representative of the vast array of scenarios in the scientific literature.

Their corresponding numbers – 2.6, 4.5, 6.0 and 8.5 – do not describe temperature rise (as some mistakenly assume), but the level of “radiative forcing” that each pathway reaches by 2100. This forcing level is a measure of the change in the Earth’s “energy balance” (in watts per square metre) caused by human-caused greenhouse gas emissions.

As the highest forcing of the set, RCP8.5 was a scenario of very high emissions and extensive global warming. 

When it was originally published in 2011, RCP8.5 was intended to reflect the high end – roughly the 90th percentile – of the baseline scenarios available in the scientific literature at the time. 

A “baseline” scenario is one that assumes no climate mitigation, explains Dr Chris Smith, senior research scholar at the International Institute for Applied Systems Analysis (IIASA) in Austria. He tells Carbon Brief:

“RCP8.5 was developed as a no-climate-policy scenario, often called ‘reference’ or ‘baseline’ scenarios. These are used to benchmark the actions of climate policy.”

Under RCP8.5, the IPCC’s fifth assessment report (AR5) in 2013 projected a best estimate of 4.3C of temperature rise by 2081-2100, compared to the pre-industrial period, with a “likely” range of 3.2C to 5.4C.

The RCPs were succeeded in 2017 by the “shared socioeconomic pathways”, or SSPs. The SSPs included a set of five socioeconomic “narratives”, which described factors such as population change, economic growth and the rate of technological development.

The SSPs were then used in the IPCC’s sixth assessment (AR6) cycle, which ran over 2015-23. The upper end of the AR6 temperature projections was provided by the successor to RCP8.5, known as SSP5-8.5, which indicated warming of 4.4C by 2081-2100, with a “very likely” range of 3.3C to 5.7C.

Why is RCP8.5 so hotly debated?

Prof Detlef van Vuuren from Utrecht University, a leading figure in the development of emissions scenarios for many years, tells Carbon Brief that RCP8.5 is a “low-probability, high-risk scenario and it was always meant like that”.

The scenario assumed a world without climate policy and was designed to explore the consequences of high levels of greenhouse gases and global warming. It was not, van Vueren says, a “best-guess scenario” of what the future held in store.

However, in some research papers, RCP8.5 was characterised as “business as usual”, suggesting that it was the likely outcome if society did not pursue climate action.

This was “incorrect”, says van Vuuren, noting that RCP8.5 “is not a likely outcome”. He adds: “It’s never been a likely outcome.”

Over time, RCP8.5 became hotly debated in academic circles, with some scientists arguing that such high emissions were becoming increasingly unlikely and others claiming that RCP8.5 was still consistent with historical cumulative carbon dioxide (CO2) emissions. 

Carbon Brief unpacked the arguments in this debate in a detailed explainer in 2019.

The charts below, originally included in a 2012 Nature commentary and then updated each year by the authors, shows how projected CO2 emissions under RCP8.5 (red line) compares with the other RCPs (bold coloured lines) and observations (black line).

The left-hand chart shows total CO2 emissions, including land-use change, while the right-hand chart shows CO2 emissions from burning fossil fuels and producing cement – the dominant drivers of 21st century emissions. 

Global total CO2 emissions from fossil fuels and land use
Global total CO2 emissions from fossil fuels and land use (left) and global fossil CO2 emissions (left) for historical observations (black lines) and the four RCP (coloured bold lines) for 1980-2050. Originally produced as part of Peters et al. (2012) and since updated by Glen Peters and Robbie Andrew.

While emission trends up to the early 2010s approximately tracked RCP8.5, a flattening of emissions growth in the years since has meant they have not kept pace with the sustained rises that were assumed in the scenario.

Over the past decade, global emissions have more closely tracked RCP4.5, one of the two “medium stabilisation scenarios” of the original four RCPs.

The debate around RCP8.5 has not just focused on current emissions, but also on the scenario’s underlying assumptions for the future. 

When it was published in 2011, the world had just seen unprecedented growth in global CO2 emissions, which had increased by 30% over the previous decade. Global coal use had increased by nearly 50% over the same period. Cleaner alternatives remained expensive in most countries and the idea of continued rapid growth in coal use seemed realistic.

Critics of RCP8.5 point to its assumptions for a dramatic expansion of coal use in the future, as well as high growth in global population.

For example, in a 2017 paper, two scientists argued that the “return to coal” envisaged in RCP8.5 would require an unprecedented five-fold increase in global coal use by the end of the century. Such an outcome was “exceptionally unlikely”, the authors wrote.

However, others have argued that while high-emissions scenarios are becoming increasingly unlikely, they still have an important role to play. For example, they highlight risks that only emerge under higher levels of warming. 

In addition, research has shown that feedbacks in the climate system – where warming triggers the release of more CO2 and methane, which warms the planet further – could mean that human-caused emissions lead to a higher radiative forcing and have a greater climate impact than initially assumed.

How has RCP8.5 been replaced?

As the IPCC heads into its seventh assessment cycle (AR7), scientists have been developing the emissions scenarios and climate model projections that will – eventually – feed into its reports.

For the emissions scenarios, that process – known as ScenarioMIP – started back in 2023 at a meeting in Reading, UK. This involved scientists representing “different climate research communities”, explains van Vuuren.

This “brainstorming” session devised the outlines for the new scenarios, he says. After more meetings, these were subsequently developed into a proposal that was – after review – translated into a journal paper. After review from scientists and the public, the final paper was published in April. 

The paper sets out seven all-new emissions scenarios, replacing the SSPs (and its predecessors, the RCPs). For simplicity, the new scenarios are named according to their levels of greenhouse gas emissions.

The figures below show the emissions (left) and the estimated global temperature changes (right) under the proposed scenarios, from the “low-to-negative” emissions scenario (turquoise) up to a “high-emissions” scenario (brown). 

The greenhouse gas emissions for each of the CMIP7 climate scenarios (left) and the associated estimated average temperature change over 2000-2150 from a 1850-1900 baseline (right) using the FaIR emulator. Source: Adapted from Van Vuuren et al. (2026)
The greenhouse gas emissions for each of the CMIP7 climate scenarios (left) and the associated estimated average temperature change over 2000-2150 from a 1850-1900 baseline (right) using the FaIR emulator. Source: Adapted from Van Vuuren et al. (2026)

(It should be noted that, while the ScenarioMIP paper has been published, there remains an embargo on using the scenario data produced by integrated assessment models – often referred to as IAMs – to publish academic papers, analysis or even social media posts until 1 September this year. Carbon Brief will publish a detailed explainer on the new scenarios once the embargo lifts.)

When compared to the SSPs that came before, the range in future emissions in the new scenarios “will be smaller”, the authors say in the paper:

“On the high-end of the range, the…high emission levels (quantified by SSP5-8.5) have become implausible, based on trends in the costs of renewables, the emergence of climate policy and recent emission trends…At the low end, many…emission trajectories have become inconsistent with observed trends during the 2020-30 period.”

In other words, the combination of technological progress and action on climate change that, to date, remains insufficient, means that scenarios of very high or very low emissions are now not considered plausible. 

Another way of looking at it is that the “range of potential futures has narrowed”, explains Smith, one of the authors on the paper.

If you “draw a fan or plume of potential future emissions that start in 2025”, it lies entirely within the spread of scenarios from a decade ago, he says:

“So you’ve ruled out futures at the high end. You’ve also ruled out futures at the low end – so it’s now not possible to limit warming to 1.5C, at least in the short term or the medium term.” 

This is a mix of “good” and “bad” news, Smith adds. 

“In the latest set of scenarios, the lowest [scenario sees] peaking at about 1.7C, so we’ve also lost that low end, but the good news is we’ve lost the high end…Back in 2010, RCP8.5 wasn’t an implausible future, we’ve now made it an implausible future, because we’ve actually bent the curve [on emissions] enough to eliminate that possibility.”

The new “high” scenario projects warming in 2100 of closer to 3.2C (with a range of 2.5C to 4.3C).

To be clear, this “high” scenario would still come with catastrophic climate impacts, even if the level of warming would remain slightly below what was set out in RCP8.5.

Van Vuuren adds that the world is “now on a trajectory to 2.5-3C of warming”. As a result, “we don’t have any scenario anymore that can reach 1.5C with limited overshoot – we will have a significant overshoot”. 

How is the IPCC involved?

Contrary to Trump’s claims, the common set of future emissions scenarios used by climate scientists are not developed by the IPCC, the UN climate-science body that produces landmark reports about climate change.

Instead, the development process described above is driven by a group of Earth system modelling experts convened by the Coupled Model Intercomparison Project (CMIP).

CMIP – an initiative of another UN body, the World Climate Research Programme – coordinates the work of dozens of climate modelling centres around the world.

Working in six-to-eight year cycles, CMIP asks modelling centres around the world to run a common set of climate-model experiments – simulations that use the same inputs and conditions – that allows for results to be collected together and more easily compared. 

For experiments that explore how the climate might change in the future, modelling centres are instructed to run simulations against a fixed set of future climate scenarios, each with different levels of concentrations of greenhouse gases, aerosols and other drivers of climate change. 

These future emissions scenarios are revisited each time CMIP embarks on a new “phase” of climate-modelling coordination, to reflect advances in scientific understanding and the pace of real-world climate action. 

The group tasked with producing the design of future scenarios, as well as the “input files” for climate models, is the “scenario model intercomparison project”, or ScenarioMIP.

CMIP aligns its work with the schedule of the IPCC, coordinating a new set of model runs for each IPCC assessment cycle. 

For example, the IPCC’s AR5 in 2013 featured climate models from the fifth phase of CMIP (CMIP5), whereas AR6 in 2021 used climate models from CMIP’s sixth phase (CMIP6).

AR7 will feature models from CMIP’s ongoing seventh phase (CMIP7). The first results from CMIP7 model runs are expected later this year. 

The IPCC is consulted during the CMIP process, van Vuuren tells Carbon Brief, but its input is “no different from any other review comment” that the ScenarioMIP team received. 

Thus, while the IPCC relies on model runs coordinated by CMIP in its landmark reports, it does not play a role in designing future emissions scenarios, nor in deciding when they should be retired. 

Dr Robert Vautard, co-chair of IPCC AR7 Working Group I, tells Carbon Brief that the IPCC does not “do or coordinate research”. Its role, he says, is to “synthesise existing knowledge” and produce “regular” reviews of climate-science literature. 

He adds that ScenarioMIP is just one set of scenarios the climate-science body assesses in its reports:

“IPCC assesses all scenarios, or sets of scenarios, that the scientific community produces. IPCC does not produce scenarios. CMIP7 will be [one] set of scenarios assessed by IPCC [for AR7] – but there will be many others.”

AI Is Changing the Way We Predict the Weather. It’s More Perilous Than We Think (Gizmodo)

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AI forecast models offer some clear benefits over traditional physical models, but they are ill-equipped to handle the increasing volatility of a warming climate.

By Ellyn Lapointe

Published April 27, 2026, 6:00 am ET

Original article

 On November 12, 1970, the Bhola cyclone slammed into the coast of what was then East Pakistan. The storm brought maximum sustained wind speeds of 130 miles per hour (205 kilometers per hour) and a 35-foot (10.5-meter) storm surge, killing an estimated 300,000 to 500,000 people.

Today, the Bhola cyclone remains the deadliest tropical storm on record. But if it had struck a decade later, it might not have been so devastating. Weather forecasting changed dramatically in the 1970s as meteorologists adopted physics-based computer models that improved storm prediction. With the rise of AI, forecasting is evolving again—but this time, experts worry the new models may be less reliable when it comes to predicting unprecedented weather events.

Researchers are calling this the “gray swan” problem. Gray swan weather extremes are physically plausible but so rare that they are poorly represented in training datasets. The trouble is, climate change is leading to more first-of-their-kind weather extremes. Think: the 2021 Pacific Northwest heatwave. This event was so severe that it would have been virtually impossible without climate change.

Physical forecast models can simulate gray swan events like the Pacific Northwest heatwave, though they are labeled extremely rare. They can do that because they are built on the laws of physics. AI models are trained on past weather data, wherein gray swans are practically nonexistent.

“They fail on gray swans,” Pedram Hassanzadeh, an associate professor of geophysical sciences at the University of Chicago, told Gizmodo. He and his colleagues published a study last April that removed all Category 3 through 5 hurricanes from an AI model’s training dataset, then tested it on Category 5 storms. The results showed that AI models cannot accurately forecast previously unseen events, as this would require extrapolation.

“The concern isn’t occasional misses. It’s that AI models can miss silently, producing confident forecasts of unremarkable weather while a record-breaking event is unfolding,” Rose Yu, an associate professor of computer science and engineering at the University of California San Diego, told Gizmodo in an email.

“Other risks matter too,” she said. “AI models can violate conservation laws in subtle ways that don’t show up in standard metrics. When they bust a forecast, diagnosing why is harder. They depend on stable observing systems, which is a real concern given current pressure on satellite programs. And institutionally, if we consolidate around AI too quickly and let physics-based infrastructure atrophy, we lose the redundancy that currently catches AI’s failures.”

The case for AI forecasting

Despite these pitfalls, meteorologists are rapidly adopting AI forecast models, and it’s actually easy to understand why. They’re faster, cheaper, and require far less computational infrastructure than physical models. When it comes to predicting typical weather patterns and events (not gray swans), their accuracy is comparable and improving rapidly.

“The typical rate of progress for most state-of-the-art physical models has been something like a day more accurate per decade, which doesn’t sound like a lot, but that’s consequential,” Andrew Charlton-Perez, a professor of meteorology and head of the School of Mathematical, Physical, and Computational Sciences at the University of Reading, told Gizmodo.

“The rate of accuracy growth for machine learning models has vastly exceeded that,” he said. “They are now competitive, and two-three years ago, they were not even in the same ballpark.”

During the 2025 Atlantic hurricane season, for example, Google DeepMind’s model outperformed nearly every physical model on storm track and intensity. In fact, since 2023, leading AI models such as GraphCast, Pangu-Weather, and the ECMWF’s AIFS have matched or outperformed the best physical models on medium-range forecasting metrics, according to Yu.

AI models are proving especially valuable in parts of the world that lack traditional forecasting resources—regions that are often on the frontlines of climate change. Hassanzadeh co-directed an initiative that provided 38 million farmers across India with AI-based monsoon forecasts, giving them up to four weeks’ advance notice of the rainy season’s onset.

“​​A lot of countries were left behind in that first revolution of weather forecasting, because [traditional] weather forecasting requires a supercomputer, hundreds of millions of dollars, various fields, workforce, and experts,” Hassanzadeh explained. AI models, by comparison, are far more accessible to lower-income countries.

Filling the knowledge gaps

Still, rapidly adopting these models without addressing the risks would be dangerous, especially in parts of the world highly vulnerable to the impacts of climate change. Shruti Nath, a postdoctoral research associate at the University of Oxford, recently co-authored an editorial calling for more rigorous testing of AI forecast models before public agencies widely adopt them.

“There is still a lot of work to be done in understanding the limits of these models, alongside where they could supplement physical models and why,” she told Gizmodo in an email.

Nath’s editorial outlines a framework for testing AI forecast models that would deliberately withhold a designated set of “iconic” extreme events (like the Pacific Northwest heat wave, for example) from the training dataset. These events would be reserved solely for testing in order to assess the models’ ability to extrapolate unprecedented weather extremes, or gray swans.

Actually implementing this AI Retraining Without Iconic Events (AIRWIE) protocol “would require the meteorological community to agree on which high-impact events constitute a rigorous benchmark,” the editorial states. This would be a great undertaking, but Nath believes most researchers agree that there is an urgent need for this kind of testing.

“We need to be a bit more organized, however, in ensuring that proper protocols can be followed and that robust safeguards are put in place and maintained by the community,” Nath said. “This is difficult when things are in such a hype phase and no one wants to miss out on the bandwagon.”

Other researchers, like Hassanzadeh, are developing ways to teach AI forecast models to predict gray swans. He and his colleagues are investigating whether combining AI systems with “relevant sampling” methods—which allow them to generate samples of gray swan events—can improve the models’ ability to extrapolate unprecedented extremes.

Efforts to understand and address the limitations of AI forecasting will be critical, because there’s no turning back now. AI is already reshaping the way we predict the weather, and as the climate becomes increasingly volatile, meteorologists will need every tool in their arsenal to be sharp and reliable. Despite their current limitations, there is much to gain from continuing to push these systems forward and figuring out how to best integrate them with physical forecasting.

“The research agenda is about making AI models physically consistent, well-calibrated, and robust to distribution shift,” Yu said. “Abandoning this approach because of the gray swan problem means giving up the biggest improvement in forecasting in a generation.”

A controversa aposta da China para ‘fabricar’ chuva – e por que muitos ainda duvidam dos resultados (BBC)

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Dois homens com jaquetas amarelas e capacetes vermelhos estão de cada lado de um lançador de foguetes, com um deles carregando um projétil. Montanhas e neblina podem ser vistas ao fundo
A China tenta aumentar artificialmente seus índices de chuva desde a década de 1950 por meio de um método conhecido, embora ainda controverso: a semeadura de nuvens

Ally Hirschlag, BBC Future

17 fevereiro 2026

Em março de 2025, uma frota de 30 aviões e drones lançou partículas de iodeto de prata no céu do norte da China. Ao atingirem o ar, o pó amarelo-pálido em seu interior emergiu e logo se transformou em “fios” acinzentados, entrelaçando o céu enquanto as aeronaves as liberavam em padrões cruzados. Muito abaixo delas, mais de 250 geradores terrestres lançavam foguetes com as mesmas partículas.

O objetivo era trazer alívio à seca nas regiões norte e noroeste, conhecidas como o cinturão de grãos do país. A grande operação foi o projeto “chuva de primavera”, conduzido pela Administração Meteorológica da China, e planejada para beneficiar as plantações no início da temporada de plantio.

A enorme operação foi aparentemente um sucesso, tendo supostamente produzido 31 milhões de toneladas adicionais de precipitação em 10 regiões suscetíveis à seca.

A China tenta aumentar artificialmente seus índices de chuva desde a década de 1950 por meio de um método conhecido, embora ainda controverso: a semeadura de nuvens.

Esse método busca estimular as nuvens a produzir mais umidade com o uso de partículas minúsculas, geralmente de iodeto de prata, cuja forma e peso são semelhantes aos de uma partícula de gelo.

A semeadura de nuvens há muito tempo gera preocupações, que vão desde os possíveis riscos ambientais e os impactos dos produtos químicos utilizados até possíveis danos a populações em áreas vizinhas, decorrentes de alterações nos padrões de chuva, além de tensões de segurança que possam surgir como consequência.

E, mesmo enquanto o país mais populoso do mundo intensifica a prática, cientistas e especialistas continuam questionando o quanto ela realmente funciona.

Caminho para a chuva

Nos últimos anos, a China intensificou de forma significativa seus esforços de semeadura de nuvens, em grande parte graças ao avanço das tecnologias de drones e de radar. O país realiza hoje modificações climáticas em mais de 50% de seu território, principalmente para aumentar a precipitação, embora também esteja tentando reduzi-la em determinadas áreas.

A técnica chegou a ser empregada para gerenciar as condições meteorológicas em datas específicas, como nos Jogos Olímpicos de Pequim, em 2008, e nas comemorações do centenário do Partido Comunista Chinês, em 2021.

A modificação do clima se tornou “um projeto vital para o desenvolvimento científico das nuvens atmosféricas e dos recursos hídricos, servindo ao país e beneficiando o povo”, afirmou Li Jiming, diretor do Centro de Modificação do Clima da China, à época da operação “chuva de primavera” de 2025. “É um componente crucial para a construção de uma nação meteorológica forte”, acrescentou, ao destacar a necessidade de impulsionar a China “de grande protagonista na modificação artificial do clima a líder global”.

Funcionários do departamento meteorológico chinês se preparam para disparar projéteis de artilharia para semeadura de nuvens em Yongchuan, em 2009
Funcionários do departamento meteorológico chinês se preparam para disparar projéteis de artilharia para semeadura de nuvens em Yongchuan, em 2009

O crescente interesse da China em controlar a precipitação é óbvia: desde a década de 1950, o país vêm enfrentando secas cada vez mais frequentes e severas, com impactos sobre a agricultura e a economia do país.

Os experimentos chineses com semeadura de nuvens começaram em 1958, quando uma aeronave supostamente teria provocado chuva sobre a província de Jilin, atingida pela seca. A técnica, porém, havia sido descoberta nos Estados Unidos uma década antes e, como tantas ideias inovadoras, totalmente por acaso.

Na década de 1940, Vincent Schaefer era pesquisador da General Electric e trabalhava para evitar que as aeronaves ficassem muito geladas durante o voo. Ele havia desenvolvido um refrigerador especial para demonstrar como o gelo se forma nas nuvens.

Um dia, ele chegou ao laboratório e descobriu que o equipamento havia desligado. Quando colocou um pedaço de gelo seco (dióxido de carbono sólido, em temperatura extremamente baixa) dentro dela para resfriar o interior, testemunhou uma reação surpreendente: cristais de gelo surgiram subitamente, flutuando dentro do compartimento. Ele havia produzido precipitação de forma artificial.

Um ano depois, em 1946, Schaefer lançou quilos de gelo seco sobre nuvens super resfriadas acima das montanhas Adirondack, no Estado de Nova York. O experimento aparentemente desencadeou uma queda de neve.

Depois dessa experiência, iniciativas de semeadura de nuvens surgiram ao redor do mundo, embora com resultados variados e inconclusivos, marcados por dificuldades na medição de dados.

Para demonstrar resultados efetivos da semeadura de nuvens, cientistas precisam de um cenário meteorológico de controle quase idêntico àquele em que tentam intervir na natureza. “Não conseguimos fazer a mesma nuvem acontecer duas vezes. Portanto, não podemos realizar um experimento controlado”, afirmou Robert Rauber, professor de ciências atmosféricas na Universidade de Illinois em Urbana-Champaign (EUA).

Semeadura de neve

Na China e em outras partes do mundo, a semeadura de nuvens, tanto para experimentos quanto para o uso prático, é realizada com mais frequência em áreas montanhosas para produzir neve, principalmente porque a neve é mais fácil de enxergar e medir do que a chuva.

Os cientistas usam radares para encontrar nuvens que contenham água líquida super-resfriada (entre -15°C e 0°C). Em seguida, liberam nelas partículas minúsculas de iodeto de prata por meio de aeronaves ou geradores instalados no solo. Essas partículas congelam ao entrar em contato com a água super-resfriada, formando cristais de gelo nas nuvens, que se tornam mais pesados e, por fim, caem no solo como neve ou gelo.

A semeadura de nuvens em clima quente funciona de maneira semelhante, mas utiliza sal para estimular pequenas gotículas de água a se unirem e aumentarem de tamanho até cair no solo. No entanto, é menos comum, porque nuvens mais quentes costumam se deslocar mais rapidamente e contêm menos água super-resfriada, além de a água não se acumular de forma tão visível quanto a neve, o que dificulta o monitoramento.

O químico americano Vincent Schaefer, que demonstrou e testou a ideia da semeadura de nuvens, tenta transformar sua respiração em cristais em 1949
O químico americano Vincent Schaefer, que demonstrou e testou a ideia da semeadura de nuvens, tenta transformar sua respiração em cristais em 1949

A primeira base operacional de semeadura de nuvens da China foi estabelecida em 2013, e hoje o país conta com seis bases que colaboram em pesquisas. Seu programa de modificação do clima é agora o maior do mundo, e as ambições de indução de chuvas cresceram na mesma proporção.

Em particular, a enorme iniciativa Tianhe (“rio do céu”, em tradução livre) do país, que visa criar um corredor de vapor de água do Planalto Tibetano até a região seca do norte da China, por meio de milhares de geradores instalados no solo.

Mas a China também enfrenta críticas diante de preocupações com os impactos mais amplos dessas operações. “Aplicadas em escala suficientemente grande, essas tecnologias de modificação climática podem representar riscos à habitabilidade e à segurança de países vizinhos”, disse Elizabeth Chalecki, pesquisadora em relações internacionais e governança tecnológica na Balsillie School of International Affairs (Canadá).

Um relatório recente argumentou que uma intervenção de tão grande escala no Planalto Tibetano poderia levar ao controle unilateral da China sobre recursos hídricos compartilhados com países vizinhos, como a Índia, levando a tensões geopolíticas. Por outro lado, uma análise ainda não publicada, baseada em 27 mil experimentos de semeadura de nuvens na China, concluiu que o impacto sobre outras nações foi mínimo.

Os potenciais danos da semeadura de nuvens podem ser exagerados, segundo Katja Friedrich, professora de ciências atmosféricas e oceânicas da Universidade do Colorado (EUA). Por exemplo, “não há indicação de que a semeadura de nuvens saia do controle e de repente você tenha essa explosão que gera uma tempestade”, disse ela em referência às inundações em Dubai, em 2024, e no Texas, em 2025, ambas erroneamente atribuídas à semeadura de nuvens.

Ainda assim, especialistas como Chalecki alertam para a ausência de políticas internacionais capazes de prevenir eventuais impactos transfronteiriços à medida que o programa chinês de modificação do clima avança. A China poderia até ser capaz de obter “um benefício de segurança auxiliar ao degradar discretamente o meio ambiente e a habitabilidade de um Estado rival”, sugere ela.

Falta de evidências

Há, no entanto, outro problema com a semeadura de nuvens: segundo cientistas, a China pode simplesmente não estar produzindo a quantidade de chuva que afirma gerar. “Acho que as alegações não são suficientemente sustentadas pelos dados”, afirmou Rauber, da Universidade de Illinois.

Na última década, o governo chinês divulgou repetidas vezes que seu programa de semeadura de nuvens estaria alcançando resultados expressivos. Um comunicado à imprensa afirmou que a iniciativa “chuva de primavera” de 2025 aumentou a precipitação na área-alvo em 20% em comparação com 2024. Já a agência meteorológica chinesa declarou, em dezembro de 2025, que as operações de chuva e neve artificial haviam produzido 168 bilhões de toneladas adicionais de precipitação (volume equivalente a cerca de 67 milhões de piscinas olímpicas) desde 2021.

O experimento Snowie, considerado referência na área, reuniu dados que indicam de forma clara que a semeadura de nuvens levou à produção de neve
O experimento Snowie, considerado referência na área, reuniu dados que indicam de forma clara que a semeadura de nuvens levou à produção de neve

“Há muitas alegações [globalmente], seja por parte de agências governamentais ou de empresas que podem se beneficiar de operações de semeadura de nuvens”, disse Jeffrey French, cientista atmosférico da Universidade do Wyoming (EUA). “Acho que há muitas declarações [vindas da China] que não podem ser validadas cientificamente nem comprovadas.”

Em 2017, French liderou um avanço significativo nas evidências sobre a técnica, quando o projeto “Snowie”, nas montanhas Payette, no Estado de Idaho (EUA), conseguiu coletar dados que demonstraram de forma inequívoca a produção de neve por meio da semeadura de nuvens. Desde então, os resultados repercutiram internacionalmente.

“Conseguimos, em diversos casos, identificar exatamente onde o material de semeadura estava nas nuvens e realizar medições diretamente nessas áreas”, afirmou French, pesquisador principal do projeto. Isso foi possível apesar de haver “tamanha variabilidade natural, tantas variações na natureza das nuvens e da precipitação”, disse.

Os pesquisadores também realizaram medições adicionais em áreas próximas, a 1 a 2 quilômetros de distância, o que permitiu comparar as duas regiões e demonstrar uma diferença clara entre a quantidade de neve produzida naturalmente e a gerada artificialmente pelo mesmo sistema de nuvens.

Foi o mais próximo que um estudo financiado de forma independente já chegou de um experimento controlado bem-sucedido na natureza. O extenso conjunto de dados do Snowie representou um marco: não apenas demonstrou que a semeadura de nuvens pode funcionar, mas também evidenciou o equilíbrio complexo de quando e como a técnica apresenta melhores resultados. Os dados viraram referência para um campo científico que carecia de comprovação empírica.

O estudo de referência foi citado em diversas pesquisas chinesas sobre semeadura de nuvens publicadas em periódicos com revisão por pares, incluindo uma que afirma que o trabalho “demonstra rigorosamente que a semeadura de nuvens realmente criou nuvens precipitantes e aumentou a precipitação na superfície”.

Resultados modestos

Ainda assim, os resultados do Snowie indicaram que o impacto da semeadura de nuvens é, no fim das contas, limitado. “É por isso que as pessoas tinham dificuldade em demonstrar o efeito nesses sistemas de precipitação”, disse Friedrich, da Universidade do Colorado. E, embora a técnica tenha sido comprovada em certa medida em outros contextos, até mesmo os cientistas que observaram os resultados de perto questionam se ela é eficaz o suficiente para justificar o esforço.

Alguns também avaliam que o uso da tecnologia avançou mais rápido do que a pesquisa científica, e que ainda não há dados confiáveis em quantidade suficiente para sustentar os resultados divulgados. “O problema desses programas de semeadura de nuvens é que a maioria é conduzida por governos, como na China ou nos Emirados Árabes Unidos”, disse Friedrich. “Mas há pouquíssima análise independente.”

Isso é relevante porque continua extremamente difícil distinguir entre a precipitação gerada pela intervenção e aquela que as nuvens produziriam naturalmente. “Em geral, é muito difícil saber se a semeadura de nuvens funciona em todos os casos”, afirmou Adele L. Igel, professora associada de física de nuvens na Universidade da Califórnia em Davis (EUA). “A teoria e a ciência indicam que deveria funcionar, mas é difícil verificar essas previsões de forma rotineira com observações e medições.”

Um soldado carrega projéteis usados na semeadura de nuvens durante uma operação para combater a seca em Xigu Township, na Província de Shanxi, no norte da China, em fevereiro de 2011
Um soldado carrega projéteis usados na semeadura de nuvens durante uma operação para combater a seca em Xigu Township, na Província de Shanxi, no norte da China, em fevereiro de 2011

Persistem ainda inúmeras limitações para que a técnica funcione de forma previsível. A semeadura de nuvens, por exemplo, não produz efeito se não houver nuvens com potencial de precipitação. Também é muito menos eficaz nos meses mais quentes, quando são raras as nuvens com água super-resfriada.

Isso significa que, em muitos casos, o custo pode superar os resultados, sobretudo quando se utilizam métodos aéreos. As técnicas baseadas em solo — que dependem de geradores que lançam iodeto de prata ou outro agente para as nuvens por meio de correntes de ar — são mais baratas, mas muito menos previsíveis. “A semeadura aérea é bastante eficiente, mas também muito cara, por isso as pessoas recorrem aos métodos terrestres”, disse Friedrich, da Universidade do Colorado.

Também é impossível prever com precisão quais serão os efeitos de modificações climáticas amplas e contínuas, seja na China ou em outros países. “É muito difícil avaliar, quanto mais prever, impactos climáticos regionais e anomalias remotas decorrentes de operações de modificação do tempo”, disse Manon Simon, professora da Universidade da Tasmânia (Austrália), que pesquisou extensivamente as implicações geopolíticas potenciais do programa chinês. Segundo ela, é particularmente complexo determinar se programas de longo prazo podem resultar em secas ou inundações mais frequentes ou intensas. A identificação desses riscos, acrescenta, exige monitoramento permanente e ampla cooperação internacional.

Uma nova fronteira

Nos quase dez anos desde o projeto Snowie, as técnicas de semeadura e as tecnologias de radar evoluíram, o que pode significar maior produção de precipitação. Com o avanço recente dos drones, a China ampliou o uso de equipamentos mais sofisticados e passou a recorrer à inteligência artificial (IA) para aumentar a precisão na liberação de iodeto de prata.

China e Emirados Árabes Unidos também experimentam métodos como o flare seeding (semeadura com sinalizadores, em tradução livre) e o envio de cargas de íons negativos às nuvens para estimular a união de gotículas, processo que leva à precipitação.

Ainda assim, como ocorre com a semeadura tradicional, permanece escassa a pesquisa independente que comprove de forma conclusiva que esses novos métodos produzem mais chuva. Os cientistas temem que o aumento das secas no mundo, impulsionado pelas mudanças climáticas, acelere a adoção da tecnologia sem que haja, na mesma proporção, estudos que indiquem quando e onde ela funciona com bom custo-benefício.

Os especialistas concordam que mais dados independentes ajudariam a identificar em que circunstâncias a semeadura pode surtir efeito e quando é improvável que funcione. As mesmas informações poderiam orientar medidas de proteção para proteger países vizinhos de eventuais impactos adversos.

Tudo isso, porém, demanda tempo, um argumento difícil de sustentar quando a escassez de água já é realidade, e muitos países buscam soluções imediatas.

Bizarre NYC Groundhog Day event with Curtis Sliwa draws hundreds of hipsters, protesters – with a possible twist next year (NY Post)

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By Nicole Rosenthal

Published Feb. 2, 2026, 3:25 p.m. ETComments

This groundhog has found a new borough.

For-hire Pennsylvania groundhog “Wolfgang” spotted his shadow at Brooklyn’s McCarren Park in front of a crowd of ecstatic hipsters Saturday, whispering his weather prediction to perennial mayoral candidate Curtis Sliwa — who claimed he’d don his own groundhog costume next year.

The woodchuck predicted six more weeks of frigid wintery temperatures to the delight of hundreds in Williamsburg who chanted Sliwa’s name and even bid for the Republican’s autograph.

A person feeds a groundhog a small piece of bread while another person in a top hat watches.
Hundreds of hipsters descended on a popular Williamsburg, Brooklyn park to watch a groundhog whisper its weather predictions into the ear of ex-mayoral candidate Curtis Sliwa Saturday.Nicole Rosenthal

“You’re glazing me!” he greeted the crowd, quoting his infamous one-liner on the debate stage to now-Mayor Zohran Mamdani last year. “I want to thank all of you … for maintaining this American tradition.”

The offbeat gathering, now in its second year, is the brainchild of political journalist Riley Callanan, 26, who told The Post that she shelled out $2,250 to rent the varmint from an animal rental service — and invited the animal-loving Sliwa as a “shot in the dark” due to his “New York icon” status among youngsters.

The Guardian Angels founder also announced a twist on next year’s event — in the vein of viral “look-alike” contests that have emerged in the Big Apple — after a handful of animal welfare activists crashed the Saturday afternoon shindig.

“Next year, I’m going to come and I’m going to audition with many of you and become a human [groundhog] next year to determine the shadow,” Sliwa suddenly declared after speaking with his “fellow animal welfare friends” at the event.

Curtis Sliwa, founder of the Guardian Angels, talks to a group of young people outdoors in the snow.
Curtis Sliwa poses with Gen Zers in McCarren Park.Nicole Rosenthal

Th groundhog “look-alike” contest will be a “nice pre-show ceremony” to Brooklyn’s new boozy bar crawl tradition, he said.

However, Callanan told The Post that she’s still “hoping” to use a real woodchuck.

Callanan previously told The Post she was inspired to begin organizing a yearly Groundhog Day tradition as a “silly way to party” in the “darkest time of the year.”

“It’s just a wholesome reason to keep fun alive,” she said.

Animal rights activists, including those from anti-horse carriage advocacy group NYCLASS and Humane Long Island, had urged organizers hours before the event to cancel over animal cruelty concerns.

“Groundhogs naturally hibernate in the winter, and forcing one into a stressful, unnatural environment with a drunk and raucous crowd of potentially thousands of people following a bar crawl is cruel and dangerous,” NYCLASS said in a statement.

“Past NYC Groundhog Day events have already resulted in injuries — and even the death of a groundhog after being dropped,” the group said, citing the fatal fumble of Staten Island Chuck after it fell out of the grip of then-Mayor Bill de Blasio.

People protest with signs saying "I Belong In My Burrow, Not This Borough" and "Wild Animals Belong In The Wild."
The news comes after animal rights activists urged organizers to cancel the event over animal cruelty concerns.Nicole Rosenthal

Sliwa, who has been outspoken on animal welfare issues like converting the city’s animal shelters to a no-kill policy, said Thursday he wasn’t sure where the groundhog had come from — but insisted he wouldn’t be holding the critter himself.

“I’m well-aware that I am not a skilled groundhog handler,” Sliwa said.

“I’m there simply to see if the groundhog sees its shadow. … I will certainly not make the mistake that Bill de Blasio did.”

Edita Birnkrant, executive director of NYCLASS, said the young organizers agreed not to use another live animal in the wintertime tradition after advocates blasted the event on social media, but Callanan argued they “did [that] to appease the protesters … and am still hoping to use a real groundhog next year.

“It was great to meet the handler and hear how well the groundhog was cared for,” she explained. “He was rescued as a baby after his family was killed in a backhoe accident and lives in the handlers’ greenhouse.

“His favorite treat is a PB&J and I’m glad his handler gave him one to munch on during the ceremony.”

Groundhog Day 2022: Staten Island Chuck makes prediction (NY Post)

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By  Joshua Rhett Miller

Published Feb. 2, 2022, 7:46 a.m. ET

The city’s rodent prognosticator signaled warmer temps and fairer skies ahead just days after the New York region got rocked by a powerful storm, dumping more than a foot of snow in some sections of Queens.

Chuck appeared after a video message from Mayor Eric Adams – the “very special honorary guest” mentioned by organizers on Facebook ahead of the annual city ritual.

Adams didn’t attend the event like his predecessor, Bill de Blasio, who opted to skip it in subsequent years after he infamously dropped Chuck’s 10-month-old stand-in, Charlotte, in 2014. The groundhog, which fell nearly six feet, died of acute internal injuries a week later.

Adams, a former New York City police officer, was instead set to attend the funeral of slain NYPD cop Wilbert Mora later Wednesday morning at St. Patrick’s Cathedral, where he was scheduled to address mourners.

But the mayor took time to send the borough’s most famous groundhog a message of encouragement from the safety of City Hall just before Chuck made his early spring prediction for the second consecutive year.

Staten Island Chuck has predicted an early spring to come for the Big Apple.
Staten Island Chuck has predicted an early spring to come for the Big Apple.Steve White

“Happy Groundhog Day, New York City,” Adams said on the clip. “It’s so great to celebrate this beloved tradition with the Staten Island Zoo.”

Ahead of Chuck’s call, Adams urged the “furry meteorologist” to portend an early spring, which he later obliged.

“I think I can speak for all New Yorkers when I say, Chuck please don’t see your shadow,” Adams said. “Bring on the sunny days! Time to see what our weatherman has to say.”

Groundhog Club handler A.J. Dereume holds Punxsutawney Phil
Punxsutawney Phil predicted six more weeks of winter this year.AP Photo/Barry Reeger, File

Moments later, Staten Island District Attorney Michael McMahon formally introduced Chuck, while noting he gained a few pounds over the winter months — much like many of the borough’s residents.

“That’s something we can all relate to,” McMahon joked.

Chuck then ambled out of a wooden enclosure and declared an early spring, prompting cheers from organizers.

“Lots of clouds,” McMahon said. “Ladies and gentlemen, I’ve just heard from Staten Island Chuck here at the Staten Island Zoo. He did not see his shadow, we will have an early spring!”

Staten Island Chuck, also known as Charles G. Hogg, has an accuracy rate of 85%, according to the Staten Island Zoo.

That’s far higher than the success rate of his Pennsylvania counterpart, Punxsutawney Phil, who is correct between 35 and 41 percent of the time depending on the data source, according to the Staten Island Advance. Phil has been right half of the time in the last decade, however.

Chuck also predicted an early spring last February — a call that zoo officials said was accurate. Punxsutawney Phil, however, had a different forecast for the second year in a row, again signaling six more weeks of winter on Wednesday during the annual Groundhog Day ceremony at Gobbler’s Knob in western Pennsylvania.

Adams, meanwhile, hopes to join the Groundhog Day festivities in coming years, mayoral spokesman Fabien Levy told The Post Tuesday.

Controversial geoengineering projects to test Earth-cooling tech funded by UK agency (Nature)

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Original article

NEWS

07 May 2025

The Advanced Research and Invention Agency is investing £57 million to study climate-manipulating technologies, but says it is taking a cautious approach.

By Jonathan O’Callaghan

andscape view as the setting sun casts shafts of light along a valley in Mid-Wales.
Solar geoengineering research involves investigating ways to ‘dim’ the Sun’s rays in an effort to cool Earth’s temperatures. Credit: Mike Kemp/In Pictures via Getty

The United Kingdom’s high-risk research agency will fund £56.8 million (US$75 million) worth of projects in the controversial area of geoengineering — manipulating Earth’s environment to avert negative effects of climate change. The 21 projects include small-scale outdoor experiments that will attempt to thicken Arctic sea ice and to brighten clouds so that they reflect more sunlight. The hope is that successful technologies could one day contribute to efforts to prevent the planet from passing dangerous climate tipping points.The UK’s $1-billion bet to create technologies that change the world

Supported by the Advanced Research and Invention Agency (ARIA) as part of its five-year Exploring Climate Cooling programme, the projects are among the most significant geoengineering experiments funded by a government.

The research has the potential to be beneficial, but must be undertaken cautiously, says Peter Frumhoff, a science-policy adviser at the Woodwell Climate Research Center in Falmouth, Massachusetts. “I am strongly supportive of responsible research on solar geoengineering and other climate interventions,” he says.

The funding package is the latest from ARIA, which was established in 2023 by the UK government and is modelled on the US Defense Advanced Research Projects Agency. With an £800-million budget, it funds high-risk, high-reward research into technologies that could have major consequences for humanity, including artificial intelligence and neurotechnology.

Divisive research

Another such area identified by ARIA was geoengineering, says Mark Symes, an electrochemist at the University of Glasgow, UK, who leads the Exploring Climate Cooling programme.

An aerial view of melting icebergs near Ilulissat, Greenland.
ARIA-funded experiments will investigate whether Earth’s diminishing ice sheets can be artificially thickened.Credit: Sean Gallup/Getty

Symes says the programme’s goal is not to find ways to replace more accepted approaches to tackling climate change, such as reducing carbon emissions. Instead, he says, geoengineering could be useful to prevent the world reaching certain tipping points that might occur before emissions reductions can have an effect. That could include “the collapse of circulations in the North Atlantic driven by the runaway melting of the Greenland ice sheet”, he says.

But even as climate change continues unabated, the concept is controversial: last year, researchers at Harvard University in Cambridge, Massachusetts, cancelled a project that would have introduced particles into the atmosphere in an effort to ‘dim’ the Sun after an outcry in Sweden, where the experiment was to take place.

Wary of such concerns, ARIA is taking a cautious approach. “We want to keep this research in the public domain,” says Piers Forster, a climate-change scientist at the University of Leeds, UK, who chairs a committee that will monitor ARIA’s climate-cooling projects. “We want it to be transparent for everyone.”

The 21 projects were selected through a competitive application process, which received about 120 proposals.

These fall into five research categories: studying ways to thicken ice sheets; assessing whether marine clouds could be brightened to offset damage to coral reefs; understanding how cirrus clouds warm the climate; looking at whether materials could be released into the stratosphere to reflect sunlight; and theoretical work on whether a sunshade deployed in space could cool portions of Earth’s surface.

Solar experiment

Five projects involve the most controversial area of geoengineering — outdoor experiments that interact with the environment. Frumhoff says that “building trust will be essential” in conducting such research. “I would be opposed to outdoor experiments being funded by any nation that isn’t aggressively and seriously reducing its own emissions,” he says.

A view of a marine cloud brightening trial on the Great Barrier Reef taken from a camera located under the wing of a research aircraft.
A cloud-brightening trial will spray seawater particles over the Great Barrier Reef to make the clouds above it whiter and more reflective.Credit: Associate Professor Daniel Harrison/Southern Cross University

The stratospheric experiment — which is among the first outdoor solar-geoengineering experiment to receive government funding — will involve using balloons to carry materials such as limestone and dolomite dust into the stratosphere, to a height of about 15–50 kilometres, to see how they respond to the conditions. No particles will be released into the stratosphere, says ARIA.

Shaun Fitzgerald at the Centre for Climate Repair in Cambridge, UK, leads one of the ice projects. His team will conduct small-scale experiments in the Norwegian Arctic archipelago of Svalbard and in Canada to pump water from beneath ice sheets and spread it on top, covering up to one square kilometre in area, to see whether such a method could thicken Earth’s diminishing ice sheets.

“We’re going to see whether we’ve actually been able to grow more sea ice in the Arctic winter,” says Fitzgerald. Early results from work that Fitzgerald’s team did last year, before receiving ARIA funding, showed ice growth of “about half a metre”, he says.

Julienne Stroeve, a sea-ice researcher at University College London, isn’t sure how effective this method would be in preventing widespread sea-ice loss. “I do not think this is feasible at any real scale needed,” she says, noting that the impact on local ecosystems is also unclear. ARIA says that Fitzgerald’s experiment will be scaled up only if it is deemed to be “ecologically sound”.

“Any small-scale outdoor experiments will be designed with safety and reversibility at their core, and will undergo environmental-impact assessment with public engagement,” says Ilan Gur, ARIA’s chief executive.

Brighter clouds

One of the cloud-brightening projects will take place off the coast of Australia, led by the Southern Cross University in New South Wales. It will use a large fan to spray seawater particles over the Great Barrier Reef, to make the clouds above it whiter and more reflective. The hope is that this could prevent global warming from damaging coral reefs. “Those particles drift upwards to the cloud base, where the tiny salt particles cause water droplets in the cloud to split into smaller droplets,” says Symes. “The smaller the droplets, the more white [the cloud] is.” The experiment will take place over 10 square kilometres.

Posed portrait of Mark Symes.
Electrochemist Mark Symes is leading ARIA’s Exploring Climate Cooling programme, which is funding £57 million worth of geoengineering projects.Credit: Matilda Hill Jenkins

The sole space-sunshade project, led by the Planetary Sunshade Foundation in Golden, Colorado, will model whether a physical reflector or a cloud of dust could be placed in space, between Earth and the Sun, to limit the amount of sunlight reaching Earth. “If you did wish to cool parts of Earth, space shades could be the most effective way,” says Symes. Nothing will be launched into space, however — the work is purely theoretical.

Responsible regulation

ARIA’s leaders hope that, by 2030, the outcomes of the programme could inform international regulations for geoengineering. One of the 21 projects will investigate how these approaches could be responsibly governed.

“The issue we are most concerned with is how to make sure activities, should they be pursued in the future, don’t lead to conflict between countries,” says project leader Matthias Honegger, a researcher at the Centre for Future Generations (CFG) in Brussels. For example, one worry is that interventions could cause side effects in neighbouring nations.

“Right now, there is no natural home for this issue within the United Nations,” says Cynthia Scharf, a senior fellow at the CFG in New York who is part of Honegger’s project. “We need to look at the substance of governance and the process of decision-making.”

Nature 641, 567-568 (2025)

doi: https://doi.org/10.1038/d41586-025-01389-1

More:

Three ways to cool Earth by pulling carbon from the sky

Divisive Sun-dimming study at Harvard cancelled: what’s next?

Por que previsões de terremotos falham tanto (BBC/Folha de S.Paulo)

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Nas redes sociais, um autoproclamado ‘previsor’ de terremotos diz que consegue prever grandes tremores, mas especialistas afirmam que é pura sorte

Artigo original (Folha de S.Paulo)

26.mar.2025 às 15h22

Ana Faguy, Christal Hayes e Max Matza

BBC News

Brent Dmitruk se autodenomina um “previsor” de terremotos.

Em meados de outubro, ele disse às suas dezenas de milhares de seguidores nas redes sociais que um terremoto atingiria em breve o ponto mais ocidental da Califórnia, ao sul da pequena cidade costeira de Eureka, nos EUA.

Dois meses depois, um tremor de magnitude 7,3 atingiu o local ao norte da Califórnia–colocando milhões de pessoas sob alerta de tsunami, e aumentando o número de seguidores de Dmitruk, que confiaram nele para prever o próximo abalo sísmico.

“Então, para as pessoas que menosprezam o que eu faço: como vocês podem argumentar que é apenas uma coincidência? É preciso ter muita habilidade para descobrir para onde os terremotos vão”, afirmou ele na véspera do Ano Novo.

A imagem mostra uma torre de alto-falantes em primeiro plano, com três alto-falantes brancos montados em um suporte. Ao fundo, é visível a Ponte Golden Gate, com suas torres vermelhas e cabos suspensos, sobre um corpo d'água. O céu está claro e azul, e a paisagem é montanhosa.
Por que previsões de terremotos falham tanto – Getty Images via BBC

Mas há um problema: os terremotos não podem ser previstos, dizem os cientistas que estudam o fenômeno.

É exatamente essa imprevisibilidade que os torna tão perturbadores. Milhões de pessoas que vivem na costa oeste da América do Norte temem que o “Big One” (que significa “O Grande”) possa acontecer a qualquer momento, alterando paisagens e inúmeras vidas.

A imagem mostra uma estrutura de ponte parcialmente destruída, com um pilar quebrado e carros estacionados nas proximidades. O cenário é de destruição, com destroços de concreto espalhados pelo chão e uma paisagem árida ao fundo.
O terremoto de Northridge, em Los Angeles, que matou 57 pessoas e feriu milhares de outras, em 1994, foi o abalo sísmico mais mortal nos EUA na memória recente – Getty Images via BBC

Lucy Jones, sismóloga que trabalhou para o Serviço Geológico dos EUA (USGS, na sigla em inglês) por mais de três décadas, e é autora de um livro chamado The Big Ones, concentrou grande parte de sua pesquisa nas probabilidades de terremotos e na melhoria da resiliência para resistir a esses eventos cataclísmicos.

Desde que começou a estudar terremotos, Jones conta que sempre houve pessoas querendo uma resposta para quando o “Big One”–que significa coisas diferentes, em regiões diferentes–vai acontecer, e alegando ter desvendado a questão.

“A necessidade humana de criar um padrão diante do perigo é extremamente forte, é uma resposta humana bastante normal ao medo”, diz ela à BBC. “No entanto, isso não tem nenhum poder de previsão.”

Com cerca de 100 mil terremotos registrados no mundo todo a cada ano, de acordo com o USGS, é compreensível que as pessoas queiram ser avisadas.

A região de Eureka, uma cidade costeira a 434 quilômetros ao norte de San Francisco, onde ocorreu o terremoto de dezembro, registrou mais de 700 terremotos somente no último ano–incluindo mais de 10 apenas na última semana, segundo os dados.

A região, onde Dmitruk adivinhou corretamente que haveria um terremoto, é uma das “áreas sismicamente mais ativas” dos EUA, de acordo com o USGS. Sua volatilidade se deve ao encontro de três placas tectônicas, uma área conhecida como Junção Tripla de Mendocino.

É o movimento das placas em relação umas às outras – seja acima, abaixo ou ao lado – que causa o acúmulo de estresse. Quando a tensão é liberada, pode ocorrer um terremoto.

Adivinhar que um tremor aconteceria aqui é uma aposta fácil, diz Jones, embora um terremoto forte, de magnitude sete, seja bastante raro.

O USGS destaca que houve apenas 11 terremotos deste tipo ou mais fortes desde 1900. Cinco deles, incluindo o que Dmitruk promoveu nas redes sociais, ocorreram na mesma região.

Embora o palpite estivesse correto, Jones afirma à BBC que é improvável que qualquer terremoto– inclusive os maiores, que devastam a sociedade–possa ser previsto com precisão.

Segundo ela, há um conjunto complexo e “dinâmico” de fatores geológicos que levam a um terremoto.

A magnitude de um terremoto é provavelmente formada à medida que o evento está ocorrendo, Jones explica, usando o ato de rasgar um pedaço de papel como analogia: o rasgo vai continuar a menos que haja algo que o interrompa ou retarde–como marcas de água que deixam o papel molhado.

Os cientistas sabem por que ocorre um terremoto – movimentos repentinos ao longo de falhas geológicas–, mas prever este evento é algo que, segundo o USGS, não pode ser feito, e algo que “não esperamos descobrir em um futuro próximo”.

A imagem mostra um cenário de destruição urbana, com edifícios em ruínas e escombros visíveis. No fundo, há prédios parcialmente intactos, enquanto a área em primeiro plano exibe paredes de tijolos danificadas e destroços. A cena é em preto e branco, sugerindo um período histórico anterior.
San Francisco ficou em ruínas após o terremoto de 1906 – Getty Images via BBC

A agência observa que pode calcular a probabilidade de terremotos em uma região específica dentro de um determinado número de anos – mas isso é o mais próximo que eles conseguem chegar.

Os registros geológicos mostram que alguns dos terremotos de maiores proporções, conhecidos como “Big Ones” pelos moradores locais, acontecem com certa regularidade. Sabe-se que a zona de subducção de Cascadia desliza a cada 300 a 500 anos, devastando regularmente a costa noroeste do Pacífico com megatsunamis de 30,5 metros de altura.

A falha de San Andreas, no sul da Califórnia, também é fonte de outro potencial “Big One”, com terremotos devastadores ocorrendo a cada 200 a 300 anos. Especialistas afirmam que o “Big One” pode acontecer a qualquer momento em qualquer uma das regiões.

Jones conta que, ao longo de sua carreira, milhares de pessoas a alertaram com previsões de um grande terremoto–inclusive indivíduos na década de 1990, que enviavam faxes para seu escritório na esperança de fazer um alerta.

“Quando você recebe uma previsão toda semana, alguém vai ter sorte, certo?”, diz ela rindo. “Mas isso geralmente subia à cabeça deles, e eles faziam mais 10 previsões que não estavam certas.”

Esta situação parece ter acontecido com Dmitruk, que não tem formação científica. Há muito tempo ele prevê que um terremoto incrivelmente grande atingiria o sudoeste do Alasca, o Japão ou as ilhas da costa da Nova Zelândia, com uma magnitude tão forte que, segundo ele, poderia interromper o comércio global.

O USGS afirma que uma previsão de terremoto precisa ter três elementos definidos – uma data e hora, o local e a magnitude do tremor – para ser útil.

Mas o cronograma de Dmitruk continua mudando.

Em um determinado momento, ele disse que o terremoto ocorreria imediatamente antes ou depois da posse do presidente dos EUA, Donald Trump.

Depois, ele anunciou que aconteceria, sem dúvida, antes de 2030.

Embora esse terremoto de grandes proporções ainda não tenha ocorrido, Dmitruk afirma que ainda acredita que vai acontecer.

“Não acredito que seja apenas por acaso”, diz Dmitruk à BBC. “Não é aleatório ou sorte.”

Este tipo de pensamento é comum quando se trata de terremotos, de acordo com Jones.

“Distribuições aleatórias podem parecer ter padrões, vemos constelações nas estrelas”, ela observa.

“Muita gente tem muito medo de terremoto, e a maneira de lidar com isso é prever [quando] eles vão acontecer.”

Como você pode se preparar diante da incerteza de um terremoto

No entanto, o fato de não ser possível prever quando vai acontecer um terremoto, não significa que você deva estar despreparado, segundo especialistas.

Todos os anos, na terceira quinta-feira de outubro, milhões de americanos participam da maior simulação de terremoto do planeta: The Great Shake Out, que pode ser traduzida como “a grande sacudida”.

O exercício foi criado por um grupo do Centro de Terremotos do Sul da Califórnia, que incluía Jones.

Durante a simulação, as pessoas praticam a orientação de “se abaixar, se cobrir e aguardar”: elas se ajoelham, se protegem sob um objeto resistente, como uma mesa, e se mantêm assim por um minuto.

O exercício se tornou tão popular desde sua criação que se espalhou pela costa propensa a terremotos para outros Estados e países.

Se estiverem ao ar livre, as pessoas são aconselhadas a ir para um espaço aberto longe de árvores, edifícios ou linhas de transmissão de energia. Perto do oceano, os moradores praticam fugir para terrenos mais altos depois que o tremor cessa, para se preparar para a possibilidade de um tsunami.

“Agora, enquanto o solo não está tremendo, enquanto não é uma situação muito estressante, é realmente o melhor momento para praticar”, afirma Brian Terbush, gerente do Programa de Terremotos e Vulcões da Divisão de Gerenciamento de Emergências do Estado de Washington, nos EUA.

Além das simulações, os moradores dos Estados da Costa Oeste americana usam um sistema de alerta telefônico mantido pelo USGS, chamado ShakeAlert.

O sistema funciona por meio da detecção de ondas de pressão emitidas por um terremoto. Embora não possa prever quando um terremoto vai ocorrer em um futuro distante, ele fornece um alerta com segundos de antecedência que podem salvar vidas. É a coisa mais próxima de um “previsor” de terremotos que foi inventada até agora.

Este texto foi publicado inicialmente aqui.

Scientists have a new explanation for the last two years of record heat (Washington Post)

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washingtonpost.com

Shannon Osaka

Feb 16, 2025

For the past few years, scientists have watched, aghast, as global temperatures have surged — with both 2023 and 2024 reachingaround 1.5 degrees Celsius above the preindustrial average. In some ways, that record heat was expected: Scientists predicted that El Niño, combined with decreasing air pollution that cools the earth, would cause temperatures to skyrocket.

But even those factors, scientists say, are not sufficient to explain the world’s recent record heat.

Earth’s overall energy imbalance — the amount of heat the planet is taking in minus the amount of heat it is releasing — also continues to rise, worrying scientists. The energy imbalance drives global warming. If it rises, scientists expect global temperatures to follow.

Two new studies offer a potential explanation: fewer clouds. And the decline in cloud cover, researchers say, could signal the start of a feedback loop that leads to more warming.

“We have added a new piece to the puzzle of where we are headed,” Helge Goessling, a climate physicist at the Alfred Wegener Institute in Germany and the author of one of the studies,saidin a video interview.

For years, scientists have struggled to incorporate clouds’ influence into the large-scale climate models that help them predict the planet’s future. Clouds can affect the climate system in two ways: First, their white surfaces reflect the sun’s light, cooling the planet. But clouds also act as a kind of blanket, reflecting infrared radiation back to the surface of the planet, just like greenhouse gases.

Which factor wins out depends on the type of cloud and its altitude. High, thin cirrus clouds tend to have more of a warming effect on the planet. Low, fluffy cumulus clouds have more of a cooling effect.

“Clouds are a huge lever on the climate system,” said Andrew Gettelman, an affiliate scientist at the University of Colorado at Boulder. “A small change in clouds could be a large change in how we warm the planet.”

Researchers are beginning to pinpoint how clouds are changing as the world warms. In Goessling’s study, published in December in the journal Science, researchers analyzed how clouds have changed over the past decade. They found that low-altitude cloud cover has fallen dramatically — which has also reduced the reflectivity of the planet. The year 2023 — which was 1.48 degrees Celsius above the preindustrial average — had the lowest albedo since 1940.

In short, the Earth is getting darker.

That low albedo, Goessling and his co-authors calculated, contributed 0.2 degrees Celsius of warming to 2023’s record-high temperatures — an amount roughly equivalent to the warming that has so far been unexplained. “This number of about 0.2 degrees fairly well fits this ‘missing warming,’” Goessling said.

Researchers are still unsure exactly what accounts for this decrease. Some believe that it could be due to less air pollution: When particulates are in the air, it can make it easier for water droplets to stick to them and form clouds.

Another possibility, Goessling said, is a feedback loop from warming temperatures. Clouds require moisture to form, and moist stratocumulus clouds sit just underneath a dry layer of air about one mile high. If temperatures warm, hot air from below can disturb that dry layer, mixing with it and making it harder for wet clouds to form.

But those changes are difficult to predict — and not all climate models show the same changes. “It’s really tricky,” Goessling said.

Other scientists have also found decliningcloud cover. In a preprint study presented at a science conference in December, a group of researchers at NASA found that some of the Earth’s cloudiest zones have been shrinking over the past two decades. Three areas of clouds — one that stretches around the Earth’s equator, and two around the stormy midlatitude zones in the Northern and Southern Hemispheres — have narrowed since 2000, decreasing the reflectivity of the Earth and warming the planet.

George Tselioudis, a climate scientist at NASA’s Goddard Institute for Space Studies and the lead author of the preprint, said this decrease in cloud cover can help explain why the Earth’s energy imbalance has been growing over the past two decades. Overall, the cloud cover in these regions is shrinking by about 1.5 percent per decade, he said, warming the Earth.

Tselioudis said that warming could be constraining these cloud-heavy regions — thus heatingthe planet.“We’ve always understood that the cloud feedback is positive — and it very well could be strong,” he said. “This seems to explain a big part of why clouds are changing the way they are.”

If the cloud changes are part of a feedback loop, scientists warn, that could indicate more warming coming, with extreme heat for billions of people around the globe. Every hot year buttresses the idea that some researchers have now embraced, that global temperature rise will reach the high end of what models had predicted. If so, the planet could pass 1.5 degrees Celsius later this decade.

Researchers now say that they are rushing to understand these effects as the planet continues to warm. “We are kind of in crunch time,” Goessling said. “We have a really strong climate signal — and from year to year it’s getting stronger.”

Superfreak pivot: When climate engineering came to South Africa (Daily Maverick)

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Our Burning Planet

Superfreak pivot: When climate engineering came to South Africa

 Illustrative image. Photo by Andy Hutchinson on Unsplash

By Kevin Bloom

22 Jan 2019 

Cooling the earth by blocking out the sun, although potentially disastrous, is now a real answer to climate change. As a Harvard research paper published late last year proved, solar geo-engineering is both technically feasible and relatively cheap. With governments and international bodies considering the technology, a South African university has just announced a study. But how convenient is this answer for our politicians and heavy emitters?

I.Global Hollywood

In his book The Planet Remade: How Geo-engineering Could Change the World, Oliver Morton laid down a potential scenario from the not-too-distant future. As briefings editor at The Economist and former chief news and features editor at the scientific journal Nature, it was a given that this scenario—a thought experiment on the deployment into the stratosphere of “climate engineering” aerosols—would be based more in science fact than science fiction. Which is exactly what made it, like the best work of Robert Heinlein or Charlie Brooker, truly terrifying.

According to a Harvard study published in November 2018, three years after the release of Morton’s book, it would work in practice like this: a fleet of purpose-built aircraft, with disproportionately large wings relative to their fuselages, so as to allow “level flight at an altitude of 20 kilometres while carrying a 25-ton payload,” would inject 0.2 million tons of sulphur dioxide into the lower stratosphere per year—thereby reflecting enough solar radiation back out into space to cut the rate of global warming progressively in half. Pre-launch costs in 2018 values would come in at $3.5 billion, with yearly operating costs at $2.25 billion. Given that in 2017 around 50 nations had military budgets of $3 billion or more, noted the Harvard scientists, the barriers to entry would be remarkably low.

“It is not a large nation that does it—indeed, it is not a single nation’s action at all,” speculated Morton back in 2015. “Sometime in the 2020s, there is a small group of them, two of which are in a position to host the runways. They call themselves the Concert; once they go public, others call them the Affront. None of them is a rich nation, but nor are they among the least developed. All of them already have low carbon-dioxide emissions, and all of them are on pathways to no emissions at all. In climate terms, they look like the good guys. But their low emissions and the esteem of the environmentally conscious part of the international community are doing nothing to reduce the climate-related risks their citizens face.”

So why “truly terrifying”?

Because, as Morton went on to explain, solar geo-engineering—otherwise known as solar radiation management, or SRM—was not (or at least was no longer) a conceptual absurdity. When he wrote his book, its probability of deployment was already based on two of the most urgent existential questions in the history of humanity: 1) Are the risks of climate change great enough to warrant serious action aimed at mitigating them? 2) Will the world’s largest industrial economies be able to lower their carbon emissions to net zero by the middle of the century?

But terrifying more specifically because, by 2018, the answer to the first question was a scientifically unqualified “yes” and to the second a statistically implausible “no”—and yet the effect of SRM on the biosphere was still unknown. With the results from the Harvard study leading to the scheduling of tests as early as the first half of 2019, the Berlin-based climate science and policy institute Climate Analytics wasted no time in recommending a global ban on the technology.

“Solar radiation management aims at limiting temperature increase by deflecting sunlight, mostly through injection of particles into the atmosphere,” the institute noted. “At best, SRM would mask warming temporarily, but more fundamentally is itself a potentially dangerous interference with the climate system.”

SRM, argued the scientists at Climate Analytics, would “alter the global hydrological cycle as well as fundamentally affect global circulation patterns such as monsoons.” It would not “halt, reverse or address in any other way the profound and dangerous problem of ocean acidification which threatens coral reefs and marine life as it does not reduce CO2 emissions and hence influence atmospheric C02 concentration.” Also, the scientists pointed out, the approach was “unlikely to attenuate the effects of global warming on global agricultural production” as its “potentially positive effect due to cooling” was projected to be counterbalanced by “negative effects on crop production of reducing solar radiation at the earth’s surface.”

In other words, according to Climate Analytics, while cooler temperatures would be helpful to the world’s farmers, the crops would still need sunlight to grow. And none of the above even counted as the number one reason that the institute was raising the alarm—SRM’s gravest danger, these scientists and policy experts insisted, was that it would divert attention from the core problem, which remained the unprecedented amount of carbon being spewed daily into the atmosphere by the extraction of coal, crude oil and natural gas.

For Morton, this was the predicament known as the “superfreak pivot”—the turning of large masses of humanity from the position that “global warming requires no emissions reduction because it isn’t a real problem” to the position that “the Concert has it all covered”. It was a predicament highlighted too by Harvard scientist David Keith, who told the Guardian in 2017:

“One of the main concerns I and everyone involved in this have is that Trump might tweet ‘geoengineering solves everything—we don’t have to bother about emissions.’ That would break the slow-moving agreement among many environmental groups that sound research in this field makes sense.”

As for South Africa, less than two months after publication of the seminal Harvard paper of late 2018, a press release was issued by the African Climate and Development Initiative of the University of Cape Town.

“UCT researchers to embark on pioneering study on potential impacts of solar geoengineering in southern Africa,” it stated.

II. Local Hollywood

As the recipient of a grant from the international DECIMALS Fund (Developing Country Impacts Modelling Analysis for SRM), the UCT team cited two reasons for going ahead with the study—and both of them had to do with the social and economic havoc that anthropogenic climate change had so far wrought in our corner of the world. First, the 2015/16 summer rainfall failure over southern Africa, which led to 30 million people becoming food insecure in South Africa, Mozambique, Botswana and Zimbabwe. Second, Cape Town almost running out of water in 2018. If SRM could be done in a safe and reliable manner, so the rationale went, it was “the only known way” to quickly offset the temperature increases that were behind the droughts.

“We want to understand the impact of solar radiation management on drought conditions,” Dr Romaric Odoulami, the project’s leader, told Daily Maverick, “that’s our motivation. What will the implications be for regional agriculture? But I want to make one thing clear: SRM has never been implemented in the real world… and we are not going to do it either.”

What the African Climate and Development Initiative was going to do, said Odoulami, was climate modelling. The project, he added, would run for the next “one or two years”—as soon as he got “something interesting,” he promised, he would let Daily Maverick know. For the moment, he wanted to leave us with this:

“Solar radiation management doesn’t stop climate change. It doesn’t stop global emissions of greenhouse gases. The only thing it does is help to reduce the global temperature by reducing the amount of solar radiation reaching the earth’s surface.”

This caution in the face of the sheer unprecedented scale of the thing was also detectable in the words of Andy Parker, project director of the Solar Radiation Management Governance Initiative, the UK-based organisation—founded in 2010 by, among others, The World Academy of Sciences and the Royal Society—that set up the DECIMALS Fund in 2018. Speaking to Daily Maverick from a conference in Bangladesh, Parker was vague yet morbidly fascinating on the legislative context that could eventually give the green light to SRM.

“That’s really tricky to predict,” he said. “We can imagine various different deployment scenarios. There’s the desperation scenario, where a country or perhaps a coalition of countries that are really suffering from climate change decide that they are going to use solar geo-engineering to stop the temperature from rising. That could be seen as unilateral and illegitimate deployment. At the other end of things, it’s possible that through the United Nations—the UN General Assembly or one of the UN conventions—there’s a much broader coalition that comes together with much more legitimacy to develop a decision-making infrastructure for if we were to ever use this, or indeed, for how we would reject it.

“Really, at this stage, we don’t know what’s going to happen. We don’t know what’s going to happen with the research, we don’t know how governments are going to deal with this, and we don’t know how quickly and how deeply the impacts of climate change are going to bite.”

In South Africa, unfortunately, all indications are that the bite is going to be serious. As Daily Maverick learned from the country’s leading land-based climate scientist in October last year, we are warming at twice the global average. At 3°C of global warming, which is 6°C regionally—and which at current emission rates we are steaming towards, as per the most conservative estimates, before the end of the century—there will be a total collapse of the maize crop and livestock industry. This is something that the Department of Environmental Affairs seems to understand well, as evidenced by their “Third National Communication” under the United Nations Framework Convention on Climate Change, submitted in March 2018.

But the other unknown factor in this general SRM universe of “unknown unknowns” is the person that currently sits atop the DEA. Has Nomvula Mokonyane, who was named at the State Capture inquiry on Monday for allegedly accepting bribes in the form of monthly cash payments, even read the Third National Communication? Does President Cyril Ramaphosa plan on replacing her with someone who will? Aside from Tito Mboweni at treasury, does anyone in the upper echelons of the ANC get the urgency of the situation?

These are the questions that highlight the possibility of South Africa one day performing the superfreak pivot. Because it might not only suit the government to defer to technology when the food and water shortages get real, it might also suit Sasol, the coal mining companies and the country’s heavy emitters at large. DM

Spray and Pray – The risky business of geoengineering Africa’s climate (Daily Maverick)

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CLIMATE GEOENGINEERING

Spray and Pray – The risky business of geoengineering Africa’s climate

 Solar Radiation Modification refers to deliberate, large-scale interventions in the global climate system to increase the amount of sunlight reflected away from the planet to reduce global temperatures. Illustrative image: (Generated with Flux AI)

By Ethan van Diemen

07 Aug 2024 

In a webinar on Tuesday, scientists and other experts agreed on the need for solar geoengineering research to enhance the portfolio of climate change responses.

Solar geoengineering, whether through space mirrors or stratospheric particles, is a complex, controversial and contentious field. In a webinar on Tuesday, atmospheric scientists and other experts from across Africa agreed that it is completely rational to explore its role in a portfolio of climate change responses. 

Geoengineering refers to deliberate, large-scale interventions in the Earth’s natural systems with the aim of counteracting climate change. The primary goal of geoengineering is to mitigate the adverse effects of global warming and manage the Earth’s climate system. There are two main categories of geoengineering: Solar Radiation Management (SRM) and Carbon Dioxide Removal (CDR).

The webinar focused on the former, which The Alliance for Just Deliberation on Solar Geoengineering says refers to “deliberate, large-scale interventions in the global climate system to increase the amount of sunlight reflected away from the planet to reduce global temperatures”.

Read more: Superfreak pivot: When climate engineering came to South Africa

The Intergovernmental Panel on Climate Change (IPCC) in its Sixth Assessment Report defines SRM as “a range of radiation modification measures not related to greenhouse gas mitigation that seek to limit global warming. Most methods involve reducing the amount of incoming solar radiation reaching the surface, but others also act on the longwave radiation budget by reducing optical thickness and cloud lifetime.”

geoengineering africa climate

(Source: The Alliance for Just Deliberation on Solar Geoengineering)

Hassaan Sipra, director of global engagement at The Alliance and a climate researcher, explained that SRM – in line with conclusions by the IPCC – is not meant to stop climate change but only to buy time for the deep reductions in greenhouse gas emissions needed to limit global warming. He also set out the context wherein SRM was an increasingly attractive area of research. 

During the UN climate conference in Paris, the world agreed to accelerate efforts to limit the global average temperature increase over pre-industrial levels to below 1.5°C. At present, we are on a trajectory to exceed even 2°C. This is important because every fraction of a degree drastically increases the risks associated with anthropogenic climate change. 

“And typically, now, within this context,” said Sipra, “what is being talked about is the use of carbon dioxide removal technologies. So we know that we’re not going to get to net zero emissions until about 2100 if we’re looking for 1.5°C. If it’s 2°C, we’re not going to get there until after 2100. So in the meantime, we also need to start scaling up our carbon dioxide removal technologies so that whatever carbon is in the atmosphere, we are immediately able to capture it and bring that back.”

Put differently, carbon removal will still be necessary in the future because even with significant reductions in greenhouse gas emissions, existing atmospheric carbon levels must be reduced to meet net zero targets and stabilise global temperatures, as outlined in the Paris Agreement. This ensures long-term climate goals are achievable by offsetting any remaining emissions.

Sipra explained that the problem with carbon dioxide removal was the interrelated problems of cost and scale. 

It’s “an expensive technology or a set of technologies that would take a long time to scale up and would require a tremendous amount of resources, and at present, those resources are not yet scalable… they’re not yet available, the technologies are not yet fully tested, and so we need a lot of time before we’re going to get to carbon dioxide removal technologies.

“We need time to cut emissions and we need time to get to carbon dioxide removal technologies. Yet climate impacts are continuing to rise in the meantime. And this is the point where for scientists, policymakers, civil society, the deliberation has begun as to what might be the possibility of buying some additional time; putting in a potential stopgap measure.”

geoengineering africa climate

Napkin diagram roughly showing SRM’s role in managing climate risks.(This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.)

SRM is a “stopgap measure”, Sipra explained, in contrast to emissions reductions or carbon dioxide removal because “it does not actually offer a solution to our climate problems, it merely masks it. And so, without addressing the root cause of climate change, you are kind of just giving yourself this, in essence, a drug which may delay – potentially – some of the impacts of climate change”.

But just how is SRM meant to achieve this? 

Prof Babatunde Abiodun, an expert in climate model developments and applications, shared some details on the state of SRM research and the various approaches being explored and experiments undertaken. Three of the projects he noted are highlighted here:

  • Stratospheric Aerosol Processes, Budget and Radiative Effects (SABRE): SABRE investigates how tiny particles in the stratosphere may reflect sunlight to cool the Earth. The project is “an extended airborne science measurement programme” and aims to understand the effectiveness and potential impacts of these aerosols so as to strengthen the “scientific foundation to inform policy decisions related to regulating global emissions that impact the stratosphere (eg ozone depleting substances, rocket exhaust) and the potential injection of material into the stratosphere to combat global warming (climate intervention)”.
  • Stratospheric Controlled Perturbation Experiment (SCoPex): SCoPex, a Harvard University-led project, explores the feasibility of dispersing reflective particles in the stratosphere to mimic volcanic cooling effects using a high-altitude balloon to release small amounts of aerosols over a small area. However, the project has recently moved away from its focus on science related to solar geoengineering.
  • Geoengineering Assessment Across Uncertainties, Scenarios and Strategies (GAUSS): GAUSS evaluates the potential risks and benefits of various geoengineering methods by using complex computer simulations. Early findings suggest that while geoengineering can reduce global temperatures, it may also lead to regional climate changes, emphasising the need for careful, scenario-based planning. They explain that “one challenge today is a degree of arbitrariness in the scenarios used in current SRM simulations”.

SRM and other geoengineering approaches, however, are not without controversy. The main concerns are the potential for unintended environmental side effects, ethical issues regarding the manipulation of natural systems and the risk of unequal impacts on different regions potentially exacerbating global inequalities.

The IPCC says in the Summary for Policymakers of its Sixth Assessment Report that, with high confidence, “solar radiation modification approaches, if they were to be implemented, introduce a widespread range of new risks to people and ecosystems, which are not well understood. Solar radiation modification approaches have the potential to offset warming and ameliorate some climate hazards, but substantial residual climate change or overcompensating change would occur at regional scales and seasonal timescales.

“Large uncertainties and knowledge gaps are associated with the potential of solar radiation modification approaches to reduce climate change risks. Solar radiation modification would not stop atmospheric CO₂ concentrations from increasing or reducing resulting ocean acidification under continued anthropogenic emissions.”

To this, the gathered scientists and experts said that while they recognised the potential risks, these should be weighed against the risk of the status quo or inaction.

“It makes sense to think about SRM as a very risky proposition, but it’s a risky proposition that has to be compared to an alternative risky proposition, which is worsening climate change. So, climate change increases risks to peoples and ecosystems. With each ton of carbon dioxide we’re adding into the atmosphere, with each incremental bit of warming, those risks rise exponentially.

“So, just like climate change has its risks, SRM has risks. It also has potential benefits, and it has a large amount of uncertainties, and none of them are well understood. So, in order to make a comparison against climate change with SRM, we need to really have an informed decision-making process around SRM so that we can have a better sense of its benefits and its drawbacks,” said Sipra.

“We need to explore SRM in the context of worsening climate change,” he said, adding that geoengineering would “not be a discussion if the climate situation had been resolved after the Rio summit when they formulated the UN Framework Convention on Climate Change.

The fact that the climate is getting worse; the fact that we are not mitigating, is the reason people are beginning to have a conversation about SRM. So, it can only ever be contextualised in comparison to climate change.” DM

Injetar partículas na atmosfera poderia reduzir temporariamente o aquecimento global (Pesquisa Fapesp)

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Polêmica, a liberação de aerossóis diminuiria a quantidade de luz solar que chega à Terra, mas seus efeitos colaterais negativos poderiam ser maiores que os positivos

Aumentar a quantidade de aerossóis na atmosfera poderia barrar a chegada à Terra de uma pequena fração da luz solar e resfriar provisoriamente o planeta. Cadan Cummings / Jacobs / JETS / NASA-JSC

Marcos Pivetta

Atualizado em 6 set 2024

Edição 343, set 2024

Depois de ter permanecido em silêncio por 600 anos, o monte Pinatubo, nas Filipinas, acordou em 1991. Uma série de pequenas explosões ao longo de dois meses culminou em uma grande erupção em meados de junho daquele ano, considerada a segunda maior do século passado. Cerca de 200 mil pessoas tiveram de deixar suas casas e mais de 700 morreram no arquipélago filipino como consequência da eclosão. A explosão produziu uma coluna de fumaça e cinzas vulcânicas que se elevou até 40 quilômetros (km) acima da superfície e invadiu a estratosfera, a segunda das cinco camadas da atmosfera que envolve a Terra. Esse manto de partículas em suspensão, geralmente com tamanhos micrométricos, atrapalhou o tráfego aéreo, queimou plantas e cultivos e produziu outros danos locais.

Apesar de ter causado grandes prejuízos materiais e a perda de vidas humanas nas Filipinas, a erupção do Pinatubo é lembrada hoje no meio científico por ter tido uma consequência surpreendente no clima global: a temperatura média da Terra reduziu-se cerca de 0,5 grau Celsius (°C) nos dois anos seguintes à sua atividade vulcânica. A enorme quantidade de partículas em suspensão, os chamados aerossóis, lançada pelo vulcão entrou no sistema de circulação de ar da estratosfera, espalhou-se pelo planeta e atuou por meses como uma espécie de filtro solar: parte dos raios do Sol que chegariam normalmente à superfície terrestre foi refletida ao incidir sobre essa quantidade extra de partículas de aerossóis injetados no sistema. Essa ação produziu um resfriamento temporário do planeta.

Os aerossóis também resfriam a Terra quando estão na troposfera, a camada mais baixa da atmosfera, mas sua ação é mais intensa na estratosfera. O efeito Pinatubo serve de inspiração para uma linha de pesquisa polêmica, cercada de incertezas científicas e riscos ambientais e geopolíticos: a geoengenharia solar ou modificação da radiação solar (SRM, na sigla derivada do inglês). Ela começou a tomar corpo lentamente nos últimos 20 anos em algumas universidades dos Estados Unidos e da Europa à medida que o aquecimento global se tornou mais pronunciado. A ideia central dessa abordagem é aumentar deliberadamente o albedo da Terra, sobretudo na estratosfera, para que ela passe a refletir mais radiação de volta ao espaço e, assim, torne-se um pouco menos quente.

Glauco Lara

O albedo é a fração da luz refletida em relação à absorvida por um corpo ou superfície. Quanto maior o albedo, como em superfícies claras ou brancas, menor a quantidade de calor absorvida. Injetar aerossóis na atmosfera é uma das formas de tentar aumentar o albedo terrestre. Alguns cálculos indicam que uma redução de 1% a 2% da quantidade de radiação solar que normalmente chega à Terra seria suficiente para diminuir sua temperatura média em um 1 °C.

A possibilidade de reduzir a quantidade de radiação solar sobre a Terra começou a ser aventada ainda na década de 1960. Mas sempre foi vista como uma excentricidade perigosa, quase um devaneio. A ideia só ganhou alguma relevância científica depois da erupção do Pinatubo e, mais recentemente, com a emergência da crise climática, causada pelo aumento significativo da temperatua global decorrente da emissão de gases de efeito estufa. Ainda assim, a pesquisa experimental – que envolveria a soltura de alguns quilos de aerossóis na estratosfera para observar seus eventuais efeitos em âmbito local (não global, como ocorreu na gigantesca erupção do vulcão nas Filipinas) – pouco progrediu até hoje em razão da oposição de parte da comunidade científica e de grupos ambientalistas.

“Até agora, existem poucos trabalhos de modelagem climática envolvendo as técnicas de geoengenharia solar”, comenta o físico Paulo Artaxo, do Instituto de Física da Universidade de São Paulo (IF-USP), especialista no estudo de aerossóis atmosféricos. “Nenhum experimento mais significativo foi feito em campo.” Duas abordagens que visam à modificação da radiação solar dominam as discussões. A principal delas é a injeção de aerossóis na estratosfera, a 15 ou 20 km de altitude, conhecida pela sigla SAI, que tenta reproduzir de forma artificial o que as grandes erupções fazem de maneira natural.

Glauco Lara

A outra, vista como de impacto mais localizado, é o clareamento de nuvens marítimas (marine cloud brightening ou MCB). Ela também envolve a liberação de aerossóis (nesse caso, partículas de sal marinho), que funcionam como núcleos de condensação das nuvens. Mas a soltura dessas partículas ocorre em altitudes bem mais baixas, de no máximo 2 km, ainda na troposfera. Com mais aerossóis, as gotas de nuvens ficam menores, refletem mais radiação solar de volta ao espaço e resfriam a superfície. Há outras técnicas cogitadas, como aumentar o albedo em grandes superfícies brancas do planeta, como o Ártico, mas as duas primeiras propostas dominam o debate.

Artaxo colabora com um grupo da Universidade Harvard, dos Estados Unidos, em estudos de modelagem computacional para tentar entender se o comportamento dos aerossóis na estratosfera é realmente similar à sua ação na troposfera. “Precisamos de mais pesquisas sobre esse tema antes de sequer pensarmos em implementar alguma intervenção desse tipo”, comenta o físico da USP, um dos coordenadores do Programa FAPESP de Pesquisa sobre Mudanças Climáticas Globais. “Não temos condições de garantir que a injeção de mais aerossóis não vá, por exemplo, diminuir as chuvas de monções no Sudeste Asiático e colocar em risco uma população de bilhões de pessoas. Se isso ocorrer, quem decide se essa injeção de aerossóis para ou continua? Esse tipo de decisão não pode ficar na mão de um pequeno grupo de países ou de um bilionário que financie um experimento desse tipo.”

Também há indícios de que uma dose extra de aerossóis na estratosfera poderia afetar a camada de ozônio, que protege a vida terrestre da ação nociva da radiação ultravioleta vinda do Sol. Isso sem falar que essas partículas em suspensão são uma forma de poluição do ar. Elas naturalmente se depositam, descem da estratosfera para a troposfera, onde podem causar ou agravar problemas de saúde, sobretudo os respiratórios. Por ora, essas e outras questões não têm respostas satisfatórias.

A posição do físico da USP é partilhada por muitos colegas. “A modificação da radiação solar é um tema sensível e o IPCC [Painel Intergovernamental sobre Mudanças Climáticas, da ONU]reconhece que ainda há muitas incertezas sobre seus potenciais efeitos”, comenta a matemática Thelma Krug, que foi vice-presidente do painel entre 2015 e 2023 e representou o Brasil em negociações internacionais sobre o clima por uma década. “Pessoalmente, sou a favor da pesquisa na área. Mas é preciso ir passo a passo com os experimentos, ter transparência e estabelecer uma governança para esse processo.”

Erupção do vulcão Pinatubo, em 1991, é considerada a segunda maior do século passadoArlan Naeg / AFP via Getty Images

O tema é tão controverso que alguns pesquisadores são contra até que se faça pesquisa sobre as técnicas de geoengenharia solar. Isso porque elas não têm impacto na redução das emissões de gases de efeito estufa, que causam o aumento da temperatura da Terra. Ainda que se mostrem relativamente seguras e eficientes em esfriar temporariamente a Terra, objetivo que hoje é apenas uma hipótese, técnicas como a SAI seriam, no máximo, paliativas. No fundo, dizem os críticos dessa abordagem, os trabalhos nessa área desviariam recursos e tomariam um tempo que poderia ser mais bem empregado na busca por ações que reduzissem a emissão de gases como dióxido de carbono (CO2) e metano (CH4). “Os estudos sobre geoengenharia solar também poderiam ser usados como a desculpa perfeita para que os grandes produtores de gases de efeito estufa não reduzissem suas emissões”, pondera o climatologista Carlos Nobre, do Instituto de Estudos Avançados (IEA) da USP.

Além de ser encarada como um diversionismo em relação à meta central de zerar as emissões de gases de efeito estufa nas próximas décadas, a adoção das técnicas de SRM poderia tornar o planeta refém desse tipo de intervenção climática por um prazo muito longo e indefinido, de décadas ou séculos. Isso criaria um problema extra: o risco de promover o chamado termination shock. Quando o planeta abandonasse o emprego das técnicas de SRM, a temperatura subiria novamente – só que dessa vez de forma muito mais rápida do que no cenário atual de aquecimento global. Isso tornaria quase impossível a adaptação a essa brusca elevação de temperatura. Qualquer oscilação significativa da temperatura, para cima ou para baixo, em um curto período, representa um desafio adaptativo.

Alguns estudos de modelagem climática têm sugerido cenários preocupantes em simulações de possíveis impactos do emprego de técnicas de geoengenharia solar. Esses trabalhos costumam averiguar que outros efeitos (colaterais) essas técnicas de intervenção no clima poderiam induzir, além da redução temporária da temperatura terrestre. Um dos problemas é que a maioria desses estudos se concentra em possíveis consequências no hemisfério Norte, onde ficam os países mais ricos e vive e trabalha a maior parte dos pesquisadores do clima.

Começam, no entanto, a surgir pesquisas com foco em outras partes do planeta. Trabalho publicado em junho deste ano na revista Environmental Research Climate sugere que a adoção da SAI ao longo deste século alteraria os prováveis impactos do aquecimento global sobre a formação de ciclones extratropicais no hemisfério Sul, como aqueles que se formam com certa regularidade na região Sul do Brasil. A previsão é de que, até o fim deste século, o aumento da temperatura global reduza o número de ciclones gerados nessa parte do globo terrestre, mas aumente a intensidade dos fenômenos produzidos. Ou seja, menos ciclones, mas mais fortes.

Glauco Lara

Quando diferentes regimes de injeção de aerossóis na estratosfera são simulados em três modelos climáticos internacionais até 2100, os resultados sinalizam um aumento na frequência de ciclones, mas uma redução em sua força em relação aos prognósticos obtidos em cenários de aquecimento global sem a adoção de qualquer protocolo da SAI. “Não somos contra nem a favor da geoengenharia solar”, diz a pesquisadora Michelle Reboita, da Universidade Federal de Itajubá (Unifei), de Minas Gerais, coordenadora do estudo. “Precisamos é estudá-la. Ela pode produzir resultados positivos em uma parte do mundo e negativos em outra.”

Há também estudos de simulação que tentam prever os possíveis impactos da SAI sobre a biodiversidade. “Nosso objetivo é entender como a SAI pode afetar as espécies de vertebrados terrestres no cenário das mudanças climáticas”, conta o biólogo brasileiro Andreas Schwarz Meyer, que faz estágio de pós-doutorado na Universidade da Cidade do Cabo, na África do Sul, e coordena um projeto de pesquisa sobre o tema. “Em outras palavras, queremos saber quais seriam as espécies ‘vencedoras’ e ‘perdedoras’ no globo caso o emprego dessas técnicas para diminuir a temperatura do planeta venha a se tornar uma realidade.”

No projeto, que ainda está em andamento, Meyer adota uma abordagem chamada perfis horizontais de biodiversidade, que usa dados climáticos históricos para estimar o intervalo térmico (a temperatura máxima e a mínima) e o grau de umidade em que as espécies ocorrem. A técnica é normalmente usada para estimar o impacto sobre as espécies de diferentes cenários de aquecimento global previstos pelo IPCC ao longo deste século.

“Assim, temos uma ideia de quantas espécies serão expostas a essas mudanças, quando e o quão rapidamente isso poderá ocorrer”, comenta o biólogo. Em 2022, o brasileiro publicou um artigo no periódico científico Philosophical Transactions of the Royal Society B em que simulou os efeitos sobre mais de 30 mil espécies de vertebrados marinhos e terrestres de um cenário particular ao longo deste século: primeiro haveria um aquecimento global superior a 2 °C e, em seguida, ocorreria uma redução de temperatura da Terra de forma artificial, por meio da remoção direta de dióxido de carbono da atmosfera. A retirada do principal gás de efeito estufa é hoje ensaiada por um conjunto de técnicas que, por ora, são muito caras e ineficientes em perseguir esse objetivo.

Trilhas de nuvens criadas no mar pela emissão de partículas de poeira por navios

A conclusão geral do estudo é que a subida e a posterior queda artificial da temperatura terrestre poderiam inviabilizar a sobrevivência de muitas espécies e produziriam danos a essas comunidades décadas após se ter atingido uma hipotética estabilização da temperatura do planeta. Meyer está fazendo um estudo semelhante agora, mas com o emprego da SAI no lugar da remoção direta de carbono.

Os trabalhos de Reboita e Meyer se dão no âmbito de uma iniciativa internacional, a Developing country governance research and evaluation for SRM, ou simplesmente Degrees. Seu objetivo é estimular estudos e formar recursos humanos especializados nas técnicas de modificação da radiação solar em países da África, América Latina e sul da Ásia. A Degrees nasceu na década passada dentro da Academia Mundial de Ciências (TWAS) e posteriormente foi assumida por uma organização não governamental britânica, a homônima Degrees. Ela financia quase 40 projetos. No Brasil, além das pesquisas da meteorologista da Unifei, duas linhas de estudo de professores da Universidade Federal de Santa Catarina (UFSC) passaram a ser apoiadas em julho passado.

Com parceiros no exterior, a equipe do engenheiro Mauricio Uriona, do Departamento de Engenharia de Produção e Sistemas da UFSC, pretende estudar como é a percepção do setor produtivo, do governo e da comunidade científica de três países (Brasil, Índia e África do Sul) sobre os potenciais riscos das técnicas de SRM. “Trabalhamos no passado com o tema da transição energética com uma abordagem de cunho socioeconômico e vimos agora uma boa oportunidade de fazer um estudo semelhante sobre geoengenharia solar”, afirma Uriona.

A socióloga ambiental Julia S. Guivant, do Instituto de Pesquisa em Riscos e Sustentabilidade (Iris), da UFSC, vai estudar como diversos atores-chave do país, como a comunidade científica, reguladores políticos, agricultores e representantes de organizações não governamentais, posicionam-se diante dos desafios de governança da geoengenharia solar. “Não temos uma posição sobre se a SRM deve ser usada ou como seu eventual emprego deve ser governado. Somos a favor das pesquisas e do debate democrático sobre o tema, diante dos problemas para atingir as metas de mitigação e adaptação às mudanças climáticas”, diz a socióloga. Colegas da USP e da Universidade Federal de São Paulo (Unifesp) vão colaborar na pesquisa coordenada por Guivant.

Há preocupação de que a geoengenharia solar possa afetar o regime das chuvas de monções na ÍndiaAmarjeet Kumar Singh / Anadolu Agency via Getty Images

As técnicas de SRM são tão polêmicas e sem qualquer tipo de regulação em acordos internacionais que mesmo grupos de pesquisas de instituições renomadas enfrentam dificuldades extremas de realizar pequenos experimentos de campo. Esses trabalhos não têm o potencial de influenciar o clima global, no máximo produzir ciência para se entender os processos envolvidos, com alguma alteração localmente. Ainda assim, os obstáculos práticos à sua realização são quase intransponíveis.

Em março deste ano, foi abandonado o Stratospheric Controlled Perturbation Experiment (SCoPEx), experimento concebido na década passada pelo grupo do físico-químico Frank Keutsch, da Universidade Harvard. A ideia da iniciativa era usar um balão de alta altitude para injetar 2 quilos de aerossóis (no caso, carbonato de cálcio) cerca de 20 km acima da superfície. “Essa quantidade de partículas é ínfima. Equivale à poluição expelida por um jato comercial durante apenas 1 minuto de voo”, disse Keutsch em entrevista dada em 2021 (ver Pesquisa FAPESP nº 303). O balão do SCoPEx era para ter ganho inicialmente os ares dos Estados Unidos em 2018. Mas isso não ocorreu. Em seguida, sua soltura foi prevista para a Suécia, também sem sucesso. Devido a protestos de ambientalistas e de grupos indígenas, o projeto nunca decolou de fato.

Alguns testes de campo com a técnica de clareamento de nuvens marinhas, uma abordagem menos ambiciosa do que a SAI, têm sido feitos, quase sempre a duras penas e diante de críticas de vários setores da sociedade. Em abril deste ano, um grupo da Universidade de Washington, dos Estados Unidos, usou um tipo de ventilador para espalhar partículas de sal marinho na pista de um navio porta-aviões aposentado que estava estacionado no litoral da cidade de Alameda, na Califórnia. A ideia da iniciativa era apenas ver se as partículas poderiam causar algum mal à saúde. Dois meses mais tarde, o município californiano proibiu esse tipo de experimento em seu território.

Na Austrália, pesquisadores da Southern Cross University e organizações locais tocam desde 2020 um projeto-piloto em que tentam aferir se a técnica de MCB pode ser útil para diminuir o branqueamento de corais na região de Townsville. O objetivo do experimento é averiguar se o método diminuiria localmente a temperatura do oceano no centro da Grande Barreira de Corais. O aquecimento das águas marinhas é a principal causa do branqueamento.

Alterar a capacidade de o Ártico refletir a luz do Sol poderia, em tese, minorar o aquecimento globalsodar99 via Getty Images

A desconfiança dos experimentos de campo deriva, em parte, do surgimento periódico de iniciativas pouco transparentes, geridas às vezes por empresas privadas obscuras. Em 2022, a Make Sunsets, uma startup norte-americana, soltou sem autorização no norte do México dois balões com aerossóis destinados à estratosfera. Pouco depois, o governo mexicano proibiu esse tipo de iniciativa em seu território. Agora, a empresa anunciou que está fazendo esse tipo de experimento nos Estados Unidos, mas os resultados dessas iniciativas são desconhecidos.

Para o físico norte-americano David Keith, da Universidade de Chicago, nos Estados Unidos, o interesse em estimular as pesquisas sobre geoengenharia solar tem aumentado, a despeito das incertezas científicas que cercam o emprego dessas técnicas. “Isso é visível nos principais relatórios internacionais, como os do Programa das Nações Unidas para o Meio Ambiente, do Programa Mundial de Pesquisa do Clima, também da ONU, e de grandes grupos ambientalistas, como Environmental Defense”, comenta Keith, em entrevista por e-mail a Pesquisa FAPESP. “Não há dúvida de que a oposição à investigação enfraqueceu, mas é difícil dizer por quê. Talvez seja por causa do aumento das temperaturas ou porque [acredito que] o mundo esteja fazendo agora esforços substanciais para reduzir as emissões de gases de efeito estufa.”

Keith foi membro do programa de geoengenharia solar de Harvard por 12 anos. Hoje ele é a favor da adoção de uma moratória internacional em experimentos de campo até que a ciência sobre o tema esteja mais bem estabelecida e haja alguma forma de governança internacional. Se esse cenário se materializar algum dia, ele diz que a humanidade deveria considerar a realização de um teste no qual se injetaria por uma década na estratosfera cerca de 10% da quantidade necessária de aerossóis para baixar em 1 °C a temperatura global. Dessa forma, seria possível conferir claramente os efeitos dessa abordagem sem correr muitos riscos.

A operação envolveria transportar cerca de 100 mil toneladas de enxofre por ano para a estratosfera – equivalente a 0,3% da quantidade de poluição por enxofre que chega anualmente à atmosfera – por uma frota de 15 jatinhos capazes de voar em altas altitudes. A operação custaria aproximadamente US$ 500 milhões ao ano. É mais uma ideia polêmica. Para alguns, é possível que a única parte boa da sugestão seja a adoção de uma moratória para esse tipo de experimento.

A reportagem acima foi publicada com o título “Controlando o sol” na edição impressa nº 343, de setembro de 2024.

Artigos científicos
REBOITA, M. S. et al. Response of the Southern Hemisphere extratropical cyclone climatology to climate intervention with stratospheric aerosol injection. Environmental Research: Climate. 20 jun. 2024.
MEYER. A.  L. S. et al. Risks to biodiversity from temperature overshoot pathways. Philosophical Transactions of the Royal Society B. 27 jun. 2022.

Andrew Ng’s new model lets you play around with solar geoengineering to see what would happen (MIT Technology Review)

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technologyreview.com

The climate emulator invites you to explore the controversial climate intervention. I gave it a whirl.

August 23, 2024

James Temple

AI pioneer Andrew Ng has released a simple online tool that allows anyone to tinker with the dials of a solar geoengineering model, exploring what might happen if nations attempt to counteract climate change by spraying reflective particles into the atmosphere.

The concept of solar geoengineering was born from the realization that the planet has cooled in the months following massive volcanic eruptions, including one that occurred in 1991, when Mt. Pinatubo blasted some 20 million tons of sulfur dioxide into the stratosphere. But critics fear that deliberately releasing such materials could harm certain regions of the world, discourage efforts to cut greenhouse-gas emissions, or spark conflicts between nations, among other counterproductive consequences.

The goal of Ng’s emulator, called Planet Parasol, is to invite more people to think about solar geoengineering, explore the potential trade-offs involved in such interventions, and use the results to discuss and debate our options for climate action. The tool, developed in partnership with researchers at Cornell, the University of California, San Diego, and other institutions, also highlights how AI could help advance our understanding of solar geoengineering. 

The current version is bare-bones. It allows users to select different emissions scenarios and various quantities of particles that would be released each year, from 25% of a Pinatubo eruption to 125%. 

Planet Parasol then displays a pair of diverging lines that represent warming levels globally through 2100. One shows the steady rise in temperatures that would occur without solar geoengineering, and the other indicates how much warming could be reduced under your selected scenario. The model can also highlight regional temperature differences on heat maps.

You can also scribble your own rising, falling, or squiggling line representing different levels of intervention across the decades to see what might happen as reflective aerosols are released.

I tried to simulate what’s known as the “termination shock” scenario, exploring how much temperatures would rise if, for some reason, the world had to suddenly halt or cut back on solar geoengineering after using it at high levels. The sudden surge of warming that could occur afterward is often cited as a risk of geoengineering. The model projects that global temperatures would quickly rise over the following years, though they might take several decades to fully rebound to the curve they would have been on if the nations in this simulation hadn’t conducted such an intervention in the first place. 

To be clear, this is an exaggerated scenario, in which I maxed out the warming and the geoengineering. No one is proposing anything like this. I was playing around to see what would happen because, well, that’s what an emulator lets you do.

You can give it a try yourself here. 

Emulators are effectively stripped-down climate models. They’re not as precise, since they don’t simulate as many of the planet’s complex, interconnected processes. But they don’t require nearly as much time and computing power to run.

International negotiators and policymakers often use climate emulators, like En-ROADS, to get a quick, rough sense of the impact that potential rules or commitments on greenhouse-gas emissions could have. 

The Parasol team wanted to develop a similar tool specifically to allow people to evaluate the potential effects of various solar geoengineering scenarios, says Daniele Visioni, a climate scientist focused on solar geoengineering at Cornell, who contributed to Planet Parasol (as well as an earlier emulator).

Climate models are steadily becoming more powerful, simulating more Earth system processes at higher resolutions, and spitting out more and more information as they do. AI is well suited to help draw meaning and understanding from that data. It’s getting ever better at spotting patterns within huge data sets and predicting outcomes based on them.

Ng’s machine-learning group at Stanford has applied AI to a growing list of climate-related subjects. Among other projects, it has developed tools to identify sources of methane emissions, recognize the drivers of deforestation, and forecast the availability of solar energy. Ng also helps oversee the AI for Climate Change bootcamp at the university.

But he says he’s been spending more and more of his time exploring the potential of solar geoengineering (sometimes referred to as solar radiation management, or SRM), given the threat of climate change and the role that AI can play in advancing the research field. 

There are “many things one can do—and that society broadly should work on—to help address climate change, first and foremost decarbonization,” he wrote in an email. “And SRM is where I’m focusing most of my climate-related efforts right now, given that this is one of the places where engineers and researchers can make a big difference (in addition to decarbonization).”

In a 2022 piece, Ng noted that AI could play several important roles in geoengineering research, including “autonomously piloting high-altitude drones” that would disperse reflective particles, modeling effects of geoengineering across specific regions, and optimizing techniques. 

Planet Parasol itself is built on top of another climate emulator, developed by researchers at the University of Leeds and the University of Oxford, that relies on the rules of physics to project global average temperatures under various scenarios. Ng’s team then harnessed machine learning to estimate the local cooling effects that could result from varying levels of solar geoengineering, says Jeremy Irvin, a grad student in his research group at Stanford.

One of the clearest limits of the current version of the tool, however, is that the results look dazzling. In the scenarios I tested, solar geoengineering cleanly cuts off the predicted rise in temperatures over the coming decades, which it may well do. 

That might lead the casual user of such a tool to conclude: Cool, let’s do it!

But even if solar geoengineering does help the world on average, it could still have negative effects, such as harming the protective ozone layer, disturbing regional rainfall patterns, undermining agriculture productivity, and changing the distribution of infectious diseases. 

None of that is incorporated in the results as yet. Plus, a climate emulator isn’t equipped to address deeply complex societal concerns. For instance, does researching such possibilities ease pressure to address the root causes of climate change? Can a tool that works at the scale of the planet ever be managed in a globally equitable way? Planet Parasol won’t be able to answer either of those questions.

Holly Buck, an environmental social scientist at the University at Buffalo and author of After Geoengineering, questioned the broader value of such a tool along similar lines.

In focus groups that she has conducted on the topic of solar geoengineering, she’s found that people easily grok the concept that it can curb warming, even without seeing the results plotted out in a model.

“They want to hear about what can go wrong, the impact on precipitation and extreme weather, who will control it, what it means existentially to fail to deal with the root of the problem, and so on,” she said in an email. “So it is hard to imagine who would actually use this and how.”

Visioni explained that the group did make a point of highlighting major challenges and concerns at the top of the page. He added that they intend to improve the tool over time in ways that will provide a fuller sense of the uncertainties, trade-offs, and regional impacts.

“This is hard, and I struggled a lot with your same observation,” Visioni wrote in an email. “But at the same time … I came to the conclusion it’s worth putting something down and work[ing] to improve it with user feedback, rather than wait until we have the perfect, nuanced version.”

As to the value of the tool, Irvin added that seeing the temperature reduction laid out clearly can make a “stronger, lasting impression.” 

“We are calling for more research to push the science forward about other areas of concern prior to potential implementation, and we hope the tool helps people understand the capabilities of SAI and support future research on it,” he said.

How Close Are the Planet’s Climate Tipping Points? (New York Times)

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nytimes.com

Raymond Zhong, Mira Rojanasakul

12 Aug 2024

Right now, every moment of every day, we humans are reconfiguring Earth’s climate bit by bit. Hotter summers and wetter storms. Higher seas and fiercer wildfires. The steady, upward turn of the dial on a host of threats to our homes, our societies and the environment around us.

We might also be changing the climate in an even bigger way.

For the past two decades, scientists have been raising alarms about great systems in the natural world that warming, caused by carbon emissions, might be pushing toward collapse. These systems are so vast that they can stay somewhat in balance even as temperatures rise. But only to a point.

Once we warm the planet beyond certain levels, this balance might be lost, scientists say. The effects would be sweeping and hard to reverse. Not like the turning of a dial, but the flipping of a switch. One that wouldn’t be easily flipped back.

Mass Death of Coral Reefs

When corals go ghostly white, they aren’t necessarily dead, and their reefs aren’t necessarily gone forever. Too much heat in the water causes the corals to expel the symbiotic algae living inside their tissues. If conditions improve, they can survive this bleaching. In time, the reefs can bounce back. As the world gets warmer, though, occasional bleaching is becoming regular bleaching. Mild bleaching is becoming severe bleaching.

Scientists’ latest predictions are grim. Even if humanity moves swiftly to rein in global warming, 70 percent to 90 percent of today’s reef-building corals could die in the coming decades. If we don’t, the toll could be 99 percent or more. A reef can look healthy right up until its corals start bleaching and dying. Eventually, it is a graveyard.

This doesn’t necessarily mean reef-building corals will go extinct. Hardier ones might endure in pockets. But the vibrant ecosystems these creatures support will be unrecognizable. There is no bouncing back anytime soon, not in the places corals live today, not at any scale.

When it might happen: It could already be underway.

Abrupt Thawing of Permafrost

In the ground beneath the world’s cold places, the accumulated remains of long-dead plants and animals contain a lot of carbon, roughly twice the amount that’s currently in the atmosphere. As heat, wildfires and rains thaw and destabilize the frozen ground, microbes get to work, converting this carbon into carbon dioxide and methane. These greenhouse gasses worsen the heat and the fire and the rain, which intensifies the thawing.

Like many of these vast, self-propelling shifts in our climate, permafrost thaw is complicated to predict. Large areas have already come unfrozen, in Western Canada, in Alaska, in Siberia. But how quickly the rest of it might defrost, how much that would add to global warming, how much of the carbon might stay trapped down there because the thawing causes new vegetation to sprout up on top of it — all of that is tricky to pin down.

“Because these things are very uncertain, there’s a bias toward not talking about it or dismissing the possibility, even,” said Tapio Schneider, a climate scientist at the California Institute of Technology. “That, I think, is a mistake,” he said. “It’s still important to explore the risks, even if the probability of occurrence in the near future is relatively small.”

When it might happen: The timing will vary place to place. The effects on global warming could accumulate over a century or more.

Collapse of Greenland Ice

The colossal ice sheets that blanket Earth’s poles aren’t melting the way an ice cube melts. Because of their sheer bigness and geometric complexity, a host of factors shapes how quickly the ice sheds its bulk and adds to the rising oceans. Among these factors, scientists are particularly concerned about ones that could start feeding on themselves, causing the melting to accelerate in a way that would be very hard to stop.

In Greenland, the issue is elevation. As the surface of the ice loses height, more of it sits at a balmier altitude, exposed to warmer air. That makes it melt even faster.

Scientists know, from geological evidence, that large parts of Greenland have been ice-free before. They also know that the consequences of another great melt could reverberate worldwide, affecting ocean currents and rainfall down into the tropics and beyond.

When it might happen: Irreversible melting could begin this century and unfold over hundreds, even thousands, of years.

Breakup of West Antarctic Ice

At the other end of the world from Greenland, the ice of western Antarctica is threatened less by warm air than by warm water.

Many West Antarctic glaciers flow out to sea, which means their undersides are exposed to constant bathing by ocean currents. As the water warms, these floating ice shelves melt and weaken from below, particularly where they sit on the seafloor. Like a dancer holding a difficult pose, the shelf starts to lose its footing. With less floating ice to hold it back, more ice from the continent’s interior would slide into the ocean. Eventually, the ice at the water’s edge might fail to support its own weight and crack into pieces.

The West Antarctic ice sheet has probably collapsed before, in Earth’s deep past. How close today’s ice is to suffering the same fate is something scientists are still trying to figure out.

“If you think about the future of the world’s coastlines, 50 percent of the story is going to be the melt of Antarctica,” said David Holland, a New York University scientist who studies polar regions. And yet, he said, when it comes to understanding how the continent’s ice might break apart, “we are at Day Zero.”

When it might happen: As in Greenland, the ice sheet could begin to recede irreversibly in this century.

Sudden Shift in the West African Monsoon

Around 15,000 years ago, the Sahara started turning green. It began when small shifts in Earth’s orbit caused North Africa to be sunnier each summer. This warmed the land, causing the winds to shift and draw in more moist air from over the Atlantic. The moisture fell as monsoon rain, which fed grasses and filled lakes, some as large as the Caspian Sea. Animals flourished: elephants, giraffes, ancestral cattle. So did humans, as engravings and rock paintings from the era attest. Only about 5,000 years ago did the region transform back into the harsh desert we know today.

Scientists now understand that the Sahara has flipped several times over the ages between arid and humid, between barren and temperate. They are less sure about how, and whether, the West African monsoon might shift or intensify in response to today’s warming. (Despite its name, the region’s monsoon unleashes rain over parts of East Africa as well.)

Whatever happens will matter hugely to an area of the world where many people’s nutrition and livelihoods depend on the skies.

When it might happen: Hard to predict.

Loss of Amazon Rainforest

Besides being home to hundreds of Indigenous communities, millions of animal and plant species and 400 billion trees; besides containing untold numbers of other living things that have yet to be discovered, named and described; and besides storing an abundance of carbon that might otherwise be warming the planet, the Amazon rainforest plays another big role. It is a living, churning, breathing engine of weather.

The combined exhalations of all those trees give rise to clouds fat with moisture. When this moisture falls, it helps keep the region lush and forested.

Now, though, ranchers and farmers are clearing the trees, and global warming is worsening wildfires and droughts. Scientists worry that once too much more of the forest is gone, this rain machine could break down, causing the rest of the forest to wither and degrade into grassy savanna.

By 2050, as much of half of today’s Amazon forest could be at risk of undergoing this kind of degradation, researchers recently estimated.

When it might happen: Will depend on how rapidly people clear, or protect, the remaining forest.

Shutdown of Atlantic Currents

Sweeping across the Atlantic Ocean, from the western coasts of Africa, round through the Caribbean and up toward Europe before heading down again, a colossal loop of seawater sets temperatures and rainfall for a big part of the globe. Saltier, denser water sinks to the ocean depths while fresher, lighter water rises, keeping this conveyor belt turning.

Now, though, Greenland’s melting ice is upsetting this balance by infusing the North Atlantic with immense new flows of freshwater. Scientists fear that if the motor slows too much, it could stall, upending weather patterns for billions of people in Europe and the tropics.

Scientists have already seen signs of a slowdown in these currents, which go by an unwieldy name: the Atlantic Meridional Overturning Circulation, or AMOC. The hard part is predicting when a slowdown might become a shutdown. At the moment, our data and records are just too limited, said Niklas Boers, a climate scientist at the Technical University of Munich and the Potsdam Institute for Climate Impact Research.

Already, though, we know enough to be sure about one thing, Dr. Boers said. “With every gram of additional CO2 in the atmosphere, we are increasing the likelihood of tipping events,” he said. “The longer we wait” to slash emissions, he said, “the farther we go into dangerous territory.”

When it might happen: Very hard to predict.

Methodology

The range of warming levels at which each tipping point might potentially be triggered is from David I. Armstrong McKay et al., Science.

The shaded areas on the maps [see here] show the present-day extent of relevant areas for each natural system. They don’t necessarily indicate precisely where large-scale changes could occur if a tipping point is reached.

2 em cada 3 pagariam mais caro em carro elétrico para combater mudanças climáticas, diz Datafolha (Folha de S.Paulo)

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Jéssica Maes

02.julho.2024

Os brasileiros estão dispostos a modificar hábitos de consumo para ajudar na luta contra o aquecimento global, mostra uma nova pesquisa Datafolha, divulgada nesta segunda-feira (1º).

Em uma questão em que foram apresentadas possíveis medidas individuais para combater as mudanças climáticas, 100% dos entrevistados afirmaram que adotariam alguma delas.

Quase a totalidade concordaria com atitudes simples, como trocar as lâmpadas de casa por modelos mais econômicos (99%) e reduzir o uso de plástico e embalagens descartáveis (94%). Os índices de aceitação são altos mesmo entre atitudes de custo superior, como colocar painéis solares em casa (89%) ou pagar mais caro por produtos com baixa emissão de carbono (74%) Dois em cada três (63%) investiriam mais por um carro elétrico (63%).

A pesquisa sobre a compreensão e a relação da população com as mudanças climáticas foi realizada presencialmente, com 2.457 pessoas de 16 anos ou mais em 130 municípios pelo Brasil, entre os dias 17 e 22 de junho. A margem de erro é de dois pontos percentuais, com taxa de confiança de 95%.

O levantamento mostra que a maioria das pessoas também aceitaria usar mais o transporte público ou a bicicleta (82%), escolher viagens para lugares mais próximos para evitar usar avião (77%) e até mesmo reduzir o consumo de carne (68%) em prol do meio ambiente.

A queima de combustíveis fósseis, como petróleo, carvão e gás, para produção de energia, transporte e pela indústria é a maior fonte de emissões de gases de efeito estufa no mundo. No Brasil, a principal fonte de emissões é o desmatamento, que tem no setor agropecuário o seu motor mais significativo.

Além disso, o plástico, que é um derivado do petróleo, ainda causa um problema ambiental por si só —especialmente aquele de uso único, como embalagens ou produtos descartáveis. Cerca de 450 milhões de toneladas desse material são descartadas por ano no mundo e apenas 9% é reciclado. Até 2050, as previsões são de que haja mais plástico do peixe nos oceanos.

Os resultados da pesquisa Datafolha apontam, ainda, que 83% dos brasileiros acreditam que atitudes individuais têm um papel importante para resolver problemas ambientais.

Metade (51%) das pessoas diz acreditar que ações individuais contribuem muito para a sustentabilidade e preservação do meio ambiente, e um terço (32%) que contribuem um pouco, enquanto apenas 16% dizem que essas atitudes não contribuem.

O índice de quem acredita na importância de ações individuais para a conservação chega a 93% entre aqueles com ensino superior, 86% para quem tem nível médio e cai a 73% entre os de nível fundamental.

A taxa também cresce, atingindo 88%, na parcela mais jovem dos entrevistados, de 16 a 24 anos. O número fica em 86% para o estrato de 25 a 44 anos, 82% para a faixa etária entre 45 e 59 anos e reduz para 76% na parcela mais velha, de 60 anos ou mais.

Ao mesmo tempo que metade dos brasileiros acreditam que ações individuais são muito significativas para a sustentabilidade, apenas 25% se sentem, pessoalmente, muito responsáveis pelas mudanças climáticas. Outros 51% dizem se sentir um pouco responsáveis e 23%, nada responsáveis. Só 1% não soube opinar.

De modo geral, ações tomadas individualmente pelos cidadãos podem contribuir para reduzir as emissões de gases que aquecem o planeta, como abrir mão de meios de transporte movidos a combustão, fazer adaptações na dieta e consumir produtos de origem sustentável, como recomendado pelo Programa das Nações Unidas para o Meio Ambiente.

Contudo, para mudar significativamente o cenário e as previsões para o futuro do clima, são necessárias grandes transformações em setores econômicos, o que requer medidas contundentes de governos e corporações.

97% dos brasileiros percebem mudanças climáticas no dia a dia, aponta Datafolha (Folha de S.Paulo)

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Jéssica Maes

02.julho.2024

Em meio a fenômenos de proporções históricas, como os alagamentos que devastaram o Rio Grande do Sul e a seca que vem causando incêndios florestais recordes no pantanal, 97% dos brasileiros afirmam que percebem no dia a dia que o planeta está passando por mudanças climáticas.

O dado pertence a uma nova pesquisa Datafolha, divulgada nesta segunda-feira (1º), que aponta que apenas 2% dos entrevistados negam a existência das alterações no clima, enquanto 1% não soube responder.

O levantamento foi realizado presencialmente, com 2.457 pessoas de 16 anos ou mais em 130 municípios pelo Brasil, entre os dias 17 e 22 de junho. A margem de erro é de dois pontos percentuais, com taxa de confiança de 95%.

Os resultados mostram que essa percepção quase unânime se repete mesmo considerando diferentes recortes, como gênero, nível de escolaridade e faixa etária —chegando, por exemplo, a 100% de concordância sobre a ocorrência das mudanças climáticas entre os mais jovens, de 16 a 24 anos.

Os índices caem, porém, quando questionados sobre os agentes que provocam essa transformação. São 77% quem acha que as mudanças climáticas são causadas principalmente pelas ações humanas, enquanto 20% defendem que a causa delas é a oscilação natural da temperatura.

Conforme aponta o consenso científico, a crise do clima atual é provocada pelos gases de efeito estufa emitidos pelas atividades humanas, principalmente a queima de combustíveis fósseis e o desmatamento, que aquecem o planeta. Em 2021, uma análise de quase 90 mil artigos científicos mostrou que mais de 99,9% dos pesquisadores do mundo concordam sobre essas causas e efeitos.

Os altos índices gerais de reconhecimento da mudança do clima podem estar relacionados ao aumento da intensidade, frequência e exposição a eventos climáticos extremos. A pesquisa perguntou se nas últimas semanas o lugar onde o entrevistado mora passou por diferentes tipos de fenômenos desta natureza, e 77% disseram que sim.

Entre esses, o número mais expressivo foi o de pessoas que passaram por calor extremo (65%), seguido de chuva intensa ou tempestade (33%), e seca extrema (29%). Enchentes atingiram 20% dos entrevistados e deslizamentos de terra, 7%.

Um quarto dos respondentes (23%) afirmou não ter vivenciado nenhum destes eventos recentemente.

Para Paulo Artaxo, professor de física da USP (Universidade de São Paulo) e membro do IPCC (Painel Intergovernamental sobre Mudanças Climáticas), vinculado à ONU, no mundo inteiro a população está percebendo que o clima mudou para pior, o que é reforçado pela ocorrência de fenômenos extremos.

“As mudanças climáticas se dão em dois níveis. Primeiro, um lento e gradual: degradação ambiental com o aumento lento da temperatura, redução ou aumento lento da precipitação, o aumento do nível do mar que afeta as áreas costeiras e assim por diante”, explica.

“Um segundo componente é a intensificação dos eventos climáticos extremos, que cada vez mais se tornam muito perceptíveis para a população em geral, causando enormes danos na saúde, na economia e na sociedade em geral”.

Marcio Astrini, secretário-executivo do Observatório do Clima, que reúne mais de uma centena de organizações ambientais, concorda.

“As pessoas não precisam mais procurar um relatório científico para se informar. Elas abrem a janela de casa, ligam a televisão e as mudanças climáticas estão acontecendo —não são mais uma previsão, são o presente”, diz. “Isso, obviamente, faz com que as pessoas tenham mais capacidade de compreender o que está acontecendo”.

O Datafolha mostra que a escolaridade é um fator que impacta a percepção dos brasileiros sobre o clima. Entre pessoas com educação de nível fundamental, 67% acreditam que as mudanças climáticas são causadas pela humanidade, 26% dizem que elas fazem parte da natureza e 4%, que não existem, Entre aquelas com ensino superior, os números são, respectivamente, 87%, 13% e 1%.

Astrini afirma que os resultados estão relacionados à falta de acesso à informação qualificada e à abundância de fake news disseminadas sobre o tema.

“Nós vivemos em um mundo em que existe desinformação em larga escala e alguns setores são alvos preferenciais de quem provoca a desinformação. O meio ambiente é um deles”, diz. “Em meio ambiente há muito, muito tempo, a gente enfrenta um verdadeiro batalhão —que vem enfraquecendo, mas ainda existe— de negacionismo, de desinformação”.

Também é entre os que passaram menos tempo na educação formal que está a taxa mais alta de descrença nas previsões da ciência sobre as consequências do aquecimento global. Daqueles que estudaram até o ensino fundamental, 43% dizem acreditar que cientistas e ambientalistas exageram sobre os impactos das mudanças climáticas, enquanto na população geral o índice é de 31%.

O nível mais alto de confiança nos especialistas está entre os mais jovens, com 77% dos que têm entre 16 e 24 anos afirmando que não há exagero a respeito do tema; 21% dizem o contrário.

Já entre aqueles com 60 anos ou mais o patamar de descrença está acima da média nacional, com mais de um terço (36%) concordando com a afirmação de que cientistas e ambientalistas exageram ao tratar dos impactos da crise do clima.

“É esperado que os mais jovens e os com mais acesso à informação mostrem maior concordância com as avaliações científicas. Os mais velhos têm a memória de condições mais estáveis e se formaram em um ambiente onde o tema não estava tão difundido, estudado ou documentado”, avalia Mercedes Bustamante, professora do departamento de ecologia da UnB (Universidade de Brasília).

Cruzando os dados da pesquisa, é possível notar, ainda, que aqueles que relatam não terem vivenciado um evento climático extremo no local onde moram são mais propensos a duvidar do parecer científico sobre os impactos do aquecimento global. Neste grupo, 36% das pessoas acham que os especialistas exageram, 61% acham que não e 3% não souberam responder.

A taxa de descrédito cai para 29% entre aqueles que passaram por alguma situação climática extrema recentemente, enquanto 69% deste estrato acha que não há exagero e 2% não soube responder.

Mais da metade dos brasileiros diz que crise do clima representa ameaça imediata, mostra Datafolha (Folha de S.Paulo)

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Jéssica Maes

02.julho.2024

Mais da metade (52%) dos brasileiros acha que as mudanças climáticas são um risco imediato para a população do planeta, enquanto 43% opinam que elas só representarão perigo para quem viverá daqui a muitos anos. Apenas 5% dizem que a crise do clima não representa risco algum.

Os números são da pesquisa Datafolha divulgada nesta segunda-feira (1º), que trata das percepções e opiniões sobre as alterações no clima. O levantamento ouviu 2.457 pessoas de 16 anos ou mais em 130 municípios pelo Brasil, entre os dias 17 e 22 de junho. A margem de erro é de dois pontos percentuais, com taxa de confiança de 95%.

“O percentual de brasileiros que compreende a mudança climática é elevado em comparação a outros países (por exemplo, os Estados Unidos)”, analisa Mercedes Bustamante, professora do departamento de Ecologia da Universidade de Brasília. Ela se refere a outros dados da pesquisa, que mostram que 77% das pessoas dizem acreditar que as mudanças climáticas são provocadas principalmente pelas atividades humanas.

A pesquisadora pondera, porém, que é interessante comparar esses índices com a divisão que aparece quando os entrevistados são questionados sobre os efeitos do aquecimento global. “Isso talvez seja uma indicação [de que há uma] percepção da existência do problema, mas ainda não [percebe-se] como seus mais variados efeitos já estão no dia a dia.”

Estudos mostram que o planeta já aqueceu mais de 1,2°C desde o período pré-industrial (1850-1900), que marca o grande aumento na emissão de carbono pela humanidade, e que fenômenos climáticos extremos, como tempestades e ondas de calor, já estão mais intensos e frequentes.

O Datafolha aponta ainda que, para 58% dos entrevistados, a humanidade não conseguirá agir para reverter os impactos das mudanças climáticas. Menos de um terço da população (31%) acha que será possível retornar a um clima mais ameno, enquanto 7% dizem que isso não faz diferença para a humanidade e o planeta.

O patamar de descrença na capacidade da humanidade de reverter as mudanças climáticas varia de acordo com a escolaridade, sendo mais alto entre aqueles que têm ensino de nível médio (60%). No estrato da população com ensino superior, 36% acreditam na possibilidade dos humanos conseguirem frear a crise climática.

Apesar disso, a pesquisa mostra que a disposição dos próprios brasileiros para mudar atitudes que têm o poder de potencializar o aquecimento global é alta.

Quase a totalidade diz que concordaria em adotar atitudes simples, como trocar as lâmpadas de casa por modelos mais econômicos (99%) e reduzir o uso de plástico (94%), e os índices de aceitação são altos mesmo diante de uma atitude custosa, como colocar paineis solares em casa (89%) e pagar mais caro por produtos com baixa emissão de carbono (74%) ou para ter um carro elétrico (63%).

Para especialistas, o que pode parecer uma contradição pode ser, na verdade, apenas desesperança com a inação de governantes e grandes corporações –que são os maiores culpados pelas emissões de gases de efeito estufa e, portanto, os principais responsáveis por reduzi-las.

“A ciência mostra caminhos para a resolução da mudança do clima. No entanto, creio que a percepção de que não haverá reversão indica a avaliação da morosidade ou mesmo falta de ações políticas concretas e robustas para abordar as soluções”, afirma Bustamante.

“A falta de ação das indústrias do petróleo e dos governos que são associados a elas, que financiam uma enorme quantidade de governos no mundo todo, está fazendo com que o planeta esteja indo por uma trajetória de aumento de temperatura médio da ordem de 3°C”, afirma o físico Paulo Artaxo, pesquisador da USP.

“Isto pode comprometer muito a qualidade de vida das próximas gerações, e isso não é para o final do século, já é para as próximas décadas”, acrescenta ele.

Para Marcio Astrini, secretário-executivo do Observatório do Clima, rede que reúne mais de uma centena de organizações ambientais, o impacto dessa desesperança da população em reverter as mudanças climáticas pode ter um efeito nocivo, de diminuir esforços nesse sentido.

“Quando o ser humano pensa, ‘olha, já que não tem jeito, então para que que eu vou me esforçar? Para resolver algo que não tem solução?’. Isso, inclusive, se reflete no voto, na escolha dos governantes que vão gerenciar a máquina estatal, que é quem vai resolver o problema”, explica.

“Isso desencadeia um problema em cima do outro, porque é uma imobilização. E quanto mais passa o tempo, mais estreita vai ficar a janela para termos alguma esperança de solução”, diz Astrini.

Análise: Fatalismo domina percepção sobre mudança climática (Folha de S.Paulo)

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Marcelo Leite

02.julho.2024

Talvez o fator mais determinante para essa opinião unânime decorra da repetição de eventos extremos, como secas incendiárias, ondas de calor mortíferas e tempestades avassaladoras. Em 2020 o fogo já devastara o pantanal, e o Sul fora açoitado por sucessivas chuvas torrenciais no segundo semestre de 2023.

Com a reincidência e o porte desses desastres, muita gente passou a ter experiência direta com flagelos. Ao Datafolha, 65% relataram ter enfrentado calor extremo, assim como 33% apontaram chuva intensa ou tempestade e 29%, seca extrema. Só um quarto (23%) afirmou não ter vivido nenhum desses eventos.

Eram favas contadas que a maioria dos 2.457 brasileiros entrevistados pelo Datafolha, de 17 a 22 de junho, acusaria os golpes seguidos do aquecimento global, diante da avalanche de imagens dantescas a cada noite na TV. Poucos ainda negam a mudança climática, mas isso não significa que o negacionismo morreu.

Só 77% dos ouvidos atribuem as alterações aos gases do efeito estufa produzidos pela atividade humana, como a queima de combustíveis fósseis (derivados de petróleo, carvão e gás natural), o desmatamento e a agropecuária. Um contingente expressivo de 20% prefere enxergar causas naturais para a crise.

Menos gente ainda, 53%, diz acreditar que o fim da normalidade seja um risco imediato para a população da Terra. Outros 43% afirmam que o impacto afetará apenas as gerações futuras.

Quase um terço dos entrevistados (31%) avalia haver exagero de pesquisadores e ambientalistas quanto a impactos da mudança climática. Esse grupo de céticos alcança 43% entre pessoas que têm nível fundamental de escolaridade.

O dado da pesquisa que causa mais alarme aponta um excesso de fatalismo: 58% dos brasileiros opinam que a humanidade será incapaz de reverter a crise do clima. Meros 31% consideram possível manter o clima sob relativo controle, e 7% dizem que não faz diferença para a humanidade ou a natureza.

Esses bolsões remanescentes de ceticismo climático refletem o sucesso parcial da propaganda negacionista em sua tática de semear dúvidas múltiplas e variadas. Quando se torna impossível contradizer a existência do aquecimento global, dado o acúmulo de evidências e medições, lança-se suspeita sobre a contribuição humana para o fenômeno.

No mesmo diapasão, argumenta-se que a sociedade humana não tem meios para contra-arrestar fenômenos em escala planetária. Em paralelo, assegura-se que os impactos não serão tão graves assim, quem sabe até benéficos.

E pensar que há supostos cientistas dispostos a propagar tais fake news, em realidade pesquisadores argentários, aposentados ou desacreditados. Essa traição à ciência tem consequências, porém.

Embora tenha muito a perder com o desvario climático, a banda atrasada do agronegócio aplaude os mercadores de dúvidas e ajuda a eleger parlamentares, sobretudo no centrão, que tanto retrocesso impuseram à pauta ambiental no governo Bolsonaro (PL) e ainda dão suas mordidas sob a ambivalência de Lula (PT).

The world’s on the verge of a carbon storage boom (MIT Technology Review)

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technologyreview.com

Hundreds of looming projects will force communities to weight the climate claims and environmental risks of capturing, moving, and storing carbon dioxide.

James Temple

June 12, 2024

Pump jacks and pipelines clutter the Elk Hills oil field of California, a scrubby stretch of land in the southern Central Valley that rests above one of the nation’s richest deposits of fossil fuels.

Oil production has been steadily declining in the state for decades, as tech jobs have boomed and legislators have enacted rigorous environmental and climate rules. Companies, towns, and residents across Kern County, where the poverty rate hovers around 18%, have grown increasingly desperate for new economic opportunities.

Late last year, California Resources Corporation (CRC), one of the state’s largest oil and gas producers, secured draft permits from the US Environmental Protection Agency to develop a new type of well in the oil field, which it asserts would provide just that. If the company gets final approval from regulators, it intends to drill a series of boreholes down to a sprawling sedimentary formation roughly 6,000 feet below the surface, where it will inject tens of millions of metric tons of carbon dioxide to store it away forever. 

They’re likely to become California’s first set of what are known as Class VI wells, designed specifically for sequestering the planet-warming greenhouse gas. But many, many similar carbon storage projects are on the way across the state, the US, and the world—a trend driven by growing government subsidies, looming national climate targets, and declining revenue and growth in traditional oil and gas activities.

Since the start of 2022, companies like CRC have submitted nearly 200 applications in the US alone to develop wells of this new type. That offers one of the clearest signs yet that capturing the carbon dioxide pollution from industrial and energy operations instead of releasing it into the atmosphere is about to become a much bigger business. 

Proponents hope it’s the start of a sort of oil boom in reverse, kick-starting a process through which the world will eventually bury more greenhouse gas than it adds to the atmosphere. They argue that embracing carbon capture and storage (CCS) is essential to any plan to rapidly slash emissions. This is, in part, because retrofitting the world’s massive existing infrastructure with carbon dioxide–scrubbing equipment could be faster and easier than rebuilding every power plant and factory. CCS can be a particularly helpful way to cut emissions in certain heavy industries, like cement, fertilizer, and paper and pulp production, where we don’t have scalable, affordable ways of producing crucial goods without releasing carbon dioxide. 

“In the right context, CCS saves time, it saves money, and it lowers risks,” says Julio Friedmann, chief scientist at Carbon Direct and previously the principal deputy assistant secretary for the Department of Energy’s Office of Fossil Energy.

But opponents insist these efforts will prolong the life of fossil-fuel plants, allow air and water pollution to continue, and create new health and environmental risks that could disproportionately harm disadvantaged communities surrounding the projects, including those near the Elk Hills oil field.

“It’s the oil majors that are proposing and funding a lot of these projects,” says Catherine Garoupa, executive director of the Central Valley Air Quality Coalition, which has tracked a surge of applications for carbon storage projects throughout the district. “They see it as a way of extending business as usual and allowing them to be carbon neutral on paper while still doing the same old dirty practices.”

A slow start

The US federal government began overseeing injection wells in the 1970s. A growing number of companies had begun injecting waste underground, sparking a torrent of water pollution lawsuits and the passage of several major laws designed to ensure clean drinking water. The EPA developed standards and rules for a variety of wells and waste types, including deep Class I wells for hazardous or even radioactive refuse and shallower Class V wells for non-hazardous fluids.

In 2010, amid federal efforts to create incentives for industries to capture more carbon dioxide, the agency added Class VI wells for CO2 sequestration. To qualify, a proposed well site must have the appropriate geology, with a deep reservoir of porous rock that can accommodate carbon dioxide molecules sitting below a layer of nonporous “cap rock” like shale. The reservoir also needs to sit well below any groundwater aquifers, so that it won’t contaminate drinking water supplies, and it must be far enough from fault lines to reduce the chances that earthquakes might crack open pathways for the greenhouse gas to escape. 

The carbon sequestration program got off to a slow start. As of late 2021, there were only two Class VI injection wells in operation and 22 applications pending before regulators.

But there’s been a flurry of proposals since—both to the EPA and to the three states that have secured permission to authorize such wells themselves, which include North Dakota, Wyoming, and Louisiana. The Clean Air Task Force, a Boston-based energy policy think tank keeping track of such projects, says there are now more than 200 pending applications.

What changed is the federal incentives. The Inflation Reduction Act of 2022 dramatically boosted the tax credits available for permanently storing carbon dioxide in geological formations, bumping it up from $50 a ton to $85 when it’s captured from industrial and power plants. The credit rose from $50 to $180 a ton when the greenhouse gas is sourced from direct-air-capture facilities, a different technology that sucks greenhouse gas out of the air. Tax credits allow companies to directly reduce their federal tax obligations, which can cover the added expense of CCS across a growing number of sectors.

The separate Bipartisan Infrastructure Law also provided billions of dollars for carbon capture demonstration and pilot projects.

A tax credit windfall 

CRC became an independent company in 2014, when Occidental Petroleum, one of the world’s largest oil and gas producers, spun it off along with many of its California assets. But the new company quickly ran into financial difficulties, filing for bankruptcy protection in 2020 amid plummeting energy demand during the early stages of the covid-19 pandemic. It emerged several months later, after restructuring its debt, converting loans into equity, and raising new lines of credit. 

The following year, CRC created a carbon management subsidiary, Carbon TerraVault, seizing an emerging opportunity to develop a new business around putting carbon dioxide back underground, whether for itself or for customers. The company says it was also motivated by the chance to “help advance the energy transition and curb rising global temperatures at 1.5 °C.”

CRC didn’t respond to inquiries from MIT Technology Review.

In its EPA application the company, based in Long Beach, California, says that hundreds of thousands of tons of carbon dioxide would initially be captured each year from a gas treatment facility in the Elk Hills area as well as a planned plant designed to produce hydrogen from natural gas. The gas is purified and compressed before it’s pumped underground.

The company says the four wells for which it has secured draft permits could store nearly 1.5 million tons of carbon dioxide per year from those and other facilities, with a total capacity of 38 million tons over 26 years. CRC says the projects will create local jobs and help the state meet its pressing climate targets.

“We are committed to supporting the state in reaching carbon neutrality and developing a more sustainable future for all Californians,” Francisco Leon, chief executive of CRC, said of the draft EPA decision in a statement. 

Those wells, however, are just the start of the company’s carbon management plans: Carbon TerraVault has applied to develop 27 additional wells for carbon storage across the state, including two more at Elk Hills, according to the EPA’s permit tracker. If those are all approved and developed, it would transform the subsidiary into a major player in the emerging business of carbon storage—and set it up for a windfall in federal tax credits. 

Carbon sequestration projects can qualify for 12 years of US subsidies. If Carbon TerraVault injects half a million tons of carbon dioxide into each of the 31 wells it has applied for over that time period, the projects could secure tax credits worth more than $15.8 billion.

That figure doesn’t take inflation into account and assumes the company meets the most stringent requirements of the law and sources all the carbon dioxide from industrial facilities and power plants. The number could rise significantly if the company injects more than that amount into wells, or if a significant share of the carbon dioxide is sourced through direct air capture. 

Chevron, BP, ExxonMobil, and Archer Daniels Midland, a major producer of ethanol, have also submitted Class VI well applications to the EPA and could be poised to secure significant IRA subsidies as well.

To be sure, it takes years to secure regulatory permits, and not every proposed project will move forward in the end. The companies involved will still need to raise financing, add carbon capture equipment to polluting facilities, and in many cases build out carbon dioxide pipelines that require separate approvals. But the increased IRA tax credits could drive as much as 250 million metric tons of additional annual storage or use of carbon dioxide in the US by 2035, according to the latest figures from the Princeton-led REPEAT Project.

“It’s a gold rush,” Garoupa says. “It’s being shoved down our throats as ‘Oh, it’s for climate goals.’” But if we’re “not doing it judiciously and really trying to achieve real emissions reductions first,” she adds, it’s merely a distraction from the other types of climate action needed to prevent dangerous levels of warming. 

Carbon accounting

Even if CCS can help drive down emissions in the aggregate, the net climate benefits from any given project will depend on a variety of factors, including how well it’s developed and run—and what other changes it brings about throughout complex, interconnected energy systems over time.

Notably, adding carbon capture equipment to a plant doesn’t trap all the climate pollution. Project developers are generally aiming for around 90%. So if you build a new project with CCS, you’ve increased emissions, not cut them, relative to the status quo.

In addition, the carbon capture process requires a lot of power to run, which may significantly increase emissions of greenhouse gas and other pollutants elsewhere by, for example, drawing on additional generation from natural-gas plants on the grid. Plus, the added tax incentives may make it profitable for a company to continue operating a fossil-fuel plant that it would otherwise have shut down or to run the facilities more hours of the day to generate more carbon dioxide to bury. 

All the uncaptured emissions associated with those changes can reduce, if not wipe out, any carbon benefits from incorporating CCS, says Danny Cullenward, a senior fellow with the Kleinman Center for Energy Policy at the University of Pennsylvania.

But none of that matters as far as the carbon storage subsidies are concerned. Businesses could even use the savings to expand their traditional oil and gas operations, he says.

“It’s not about the net climate impact—it’s about the gross tons you stick under ground,” Cullenward says of the tax credits.

A study last year raised a warning about how that could play out in the years to come, noting that the IRA may require the US to provide hundreds of billions to trillions of dollars in tax credits for power plants that add CCS. Under the scenarios explored, those projects could collectively deliver emissions reductions of as much as 24% or increases as high as 82%. The difference depends largely on how much the incentives alter energy production and the degree to which they extend the life of coal and natural-gas plants.

Coauthor Emily Grubert, an associate professor at Notre Dame and a former deputy assistant secretary at the Department of Energy, stressed that regulators must carefully consider these complex, cascading emissions impacts when weighing whether to approve such proposals.

“Not taking this seriously risks potentially trillions of dollars and billions of tonnes of [greenhouse-gas] emissions, not to mention the trust and goodwill of the American public, which is reasonably skeptical of these potentially critically important technologies,” she wrote in an op-ed in the industry outlet Utility Dive.

Global goals

Other nations and regions are also accelerating efforts to capture and store carbon as part of their broader efforts to lower emissions and combat climate change. The EU, which has dedicated tens of billions of euros to accelerating the development of CCS, is working to develop the capacity to store 50 million tons of carbon dioxide per year by 2030, according to the Global CCS Institute’s 2023 industry report.

Likewise, Japan hopes to sequester 240 million tons annually by 2050, while Saudi Arabia is aiming for 44 million tons by 2035. The industry trade group said there were 41 CCS projects in operation around the world at the time, with another 351 under development.

A handful of US facilities have been capturing carbon dioxide for decades for a variety of uses, including processing or producing natural gas, ammonia, and soda ash, which is used in soaps, cosmetics, baking soda, and other goods.

But Ben Grove, carbon storage manager at the Clean Air Task Force, says the increased subsidies in the IRA made CCS economical for many industry segments in the US, including: chemicals, petrochemicals, hydrogen, cement, oil, gas and ethanol refineries, and steel, at least on the low end of the estimated cost ranges. 

In many cases, the available subsidies still won’t fully cover the added cost of CCS in power plants and certain other industrial facilities. But the broader hope is that these federal programs will help companies scale up and optimize these processes over time, driving down the cost of CCS and making it feasible for more sectors, Grove says.

‘Against all evidence’

In addition to the gas treatment and hydrogen plants, CRC says, another source for the captured carbon dioxide could eventually include its own Elk Hills Power Plant, which runs on natural gas extracted from the oil field. The company has said it intends to retrofit the facility to capture 1.5 million tons of emissions a year.

Still other sources could include renewable fuels plants, which may mean biofuel facilities, steam generators, and a proposed direct-air-capture plant that would be developed by the carbon-removal startup Avnos, according to the EPA filing. Carbon TerraVault is part of a consortium, which includes Avnos, Climeworks, Southern California Gas Company, and others, that has proposed developing a direct-air-capture hub in Kern County, where the Elk Hills field is located. Last year, the Department of Energy awarded the so-called California DAC Hub nearly $12 million to conduct engineering design studies for direct-air-capture facilities.

CCS may be a helpful tool for heavy industries that are really hard to clean up, but that’s largely not what CRC has proposed, says Natalia Ospina, legal director at the Center on Race, Poverty & the Environment, an environmental-justice advocacy organization in Delano, California. 

“The initial source will be the Elk Hills oil field itself and the plant that refines gas in the first place,” she says. “That is just going to allow them to extend the life of the oil and gas industry in Kern County, which goes against all the evidence in front of us in terms of how we should be addressing the climate crisis.”

Natalia Ospina
Natalia Ospina, legal director at the Center on Race, Poverty & the Environment.

Critics of the project also fear that some of these facilities will continue producing other types of pollution, like volatile organic compounds and fine particulate matter, in a region that’s already heavily polluted. Some analyses show that adding a carbon capture process reduces those other pollutants in certain cases. But Ospina argues that oil and gas companies can’t be trusted to operate such projects in ways that reduce pollution to the levels necessary to protect neighboring communities.

‘You need it’

Still, a variety of studies, from the state level to the global, conclude that CCS may play an essential role in cutting greenhouse-gas emissions fast enough to moderate the global dangers of climate change.

California is banking heavily on capturing carbon from plants or removing it from the air through various means to meet its 2045 climate neutrality goal, aiming for 20 million metric tons by 2030 and 100 million by midcentury. The Air Resources Board, the state’s main climate regulator, declared that “there is no path to carbon neutrality without carbon removal and sequestration.” 

Recent reports from the UN’s climate panel have also stressed that carbon capture could be a “critical mitigation option” for cutting emissions from cement and chemical production. The body’s modeling study scenarios that limit global warming to 1.5 °C over preindustrial levels rely on significant levels of CCS, including tens to hundreds of billions of tons of carbon dioxide captured this century from plants that use biomatter to produce heat and electricity—a process known as BECCS.

Meeting global climate targets without carbon capture would require shutting down about a quarter of the world’s fossil-fuel plants before they’ve reached the typical 50-year life span, the International Energy Agency notes. That’s an expensive proposition, and one that owners, investors, industry trade groups, and even nations will fiercely resist.

“Everyone keeps coming to the same conclusion, which is that you need it,” Friedmann says.

Lorelei Oviatt, director of the Kern County Planning and Natural Resources Department, declined to express an opinion about CRC’s Elk Hills project while local regulators are reviewing it. But she strongly supports the development of CCS projects in general, describing it as a way to help her region restore lost tax revenue and jobs as “the state puts the area’s oil companies out of business” through tighter regulations.

County officials have proposed the development of a more than 4,000-acre carbon management park, which could include hydrogen, steel, and biomass facilities with carbon-capture components. An economic analysis last year found that the campus and related activities could create more than 22,000 jobs, and generate more than $88 million in sales and property taxes for the economically challenged county and cities, under a high-end scenario. 

Oviatt adds that embracing carbon capture may also allow the region to avoid the “stranded asset” problem, in which major employers are forced to shut down expensive power plants, refineries, and extraction wells that could otherwise continue operating for years to decades.

“We’re the largest producer of oil in California and seventh in the country; we have trillions and trillions of dollars in infrastructure,” she says. “The idea that all of that should just be abandoned does not seem like a thoughtful way to design an economy.”

Carbon dioxide leaks

But critics fear that preserving it simply means creating new dangers for the disproportionately poor, unhealthy, and marginalized communities surrounding these projects.

In a 2022 letter to the EPA, the Center for Biological Diversity raised the possibility that the sequestered carbon dioxide could leak out of wells or pipelines, contributing to climate change and harming local residents.

These concerns are not without foundation.

In February 2020, Denbury Enterprises’ Delta pipeline, which stretches more than 100 miles between Mississippi and Louisiana, ruptured and released more than 30,000 barrels’ worth of compressed, liquid CO2 gas near the town of Satartia, Mississippi. 

The leak forced hundreds of people to evacuate their homes and sent dozens to local hospitals, some struggling to breathe and others unconscious and foaming at the mouth, as the Huffington Post detailed in an investigative piece. Some vehicles stopped running as well: the carbon dioxide in air displaced oxygen, which is essential to the combustion in combustion engines.

There have also been repeated carbon dioxide releases over the last two decades at an enhanced oil recovery project at the Salt Creek oil field in Wyoming. Starting in the late 1800s, a variety of operators have drilled, abandoned, sealed, and resealed thousands of wells at the site, with varying degrees of quality, reliability, and documentation, according to the Natural Resources Defense Council. A sustained leak in 2004 emitted 12,000 cubic feet of the gas per day, on average, while a 2016 release of carbon dioxide and methane forced a school near the field to relocate its classes for the remainder of the year.

Some fear that similar issues could arise at Elk Hills, which could become the nation’s first carbon sequestration project developed in a depleted oil field. Companies have drilled and operated thousands of wells over decades at the site, many of which have sat idle and unplugged for years, according to a 2020 investigation by the Los Angeles Times and the Center for Public Integrity.

Ospina argues that CRC and county officials are asking the residents of Kern County to act as test subjects for unproven and possibly dangerous CCS use cases, compounding the health risks facing a region that is already exposed to too many.

Whether the Elk Hills project moves forward or not, the looming carbon storage boom will soon force many other areas to wrestle with similar issues. What remains to be seen is whether companies and regulators can adequately address community fears and demonstrate that the climate benefits promised in modeling studies will be delivered in reality. 

Update: This story was updated to remove a photo that was not of the Elk Hills oil field and had been improperly captioned.

Ditching ‘Anthropocene’: why ecologists say the term still matters (Nature)

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A aerial view of a section of the Niger river in Bamako clogged with plastic waste and other polluting materials.
Plastic waste is clogging the Niger River in Bamako, Mali. After it sediments, plastic will become part of the geological record of human impacts on the planet. Credit: Michele Cattani/AFP via Getty

Original article

Beyond stratigraphic definitions, the name has broader significance for understanding humans’ place on Earth.

David Adam

14 March 2024

After 15 years of discussion, geologists last week decided that the Anthropocene — generally understood to be the age of irreversible human impacts on the planet — will not become an official epoch in Earth’s geological timeline.

The rejected proposal would have codified the end of the current Holocene epoch, which has been in place since the end of the last ice age 11,700 years ago. It suggested that the Anthropocene started in 1952, when plutonium from hydrogen-bomb tests showed up in the sediment of Crawford Lake near Toronto, Canada.

The vote has drawn controversy over procedural details, and debate about its legitimacy continues. But whether or not it’s formally approved as a stratigraphic term, the idea of the Anthropocene is now firmly rooted in research. So, how are scientists using the term, and what does it mean to them and their fields?

‘It’s a term that belongs to everyone’

As head of the Leverhulme Centre for Anthropocene Biodiversity at the University of York, UK, Chris Thomas has perhaps more riding on the term than most. “When the news of this — what sounds like a slightly dodgy vote — happened, I sort of wondered, is it the end of us? But I think not,” he says.

For Thomas, the word Anthropocene neatly summarizes the sense that humans are part of Earth’s system and integral to its processes — what he calls indivisible connectedness. “That helps move us away from the notion that somehow humanity is apart from the rest of nature and natural systems,” he says. “It’s undoable — the change is everywhere.”

The concept of an era of human-driven change also provides convenient common ground for him to collaborate with researchers from other disciplines. “This is something that people in the arts and humanities and the social sciences have picked up as well,” he says. “It is a means of enabling communication about the extent to which we are living in a truly unprecedented and human-altered world.”

Seen through that lens, the fact that the Anthropocene has been formally rejected because scientists can’t agree on when it began seems immaterial. “Many people in the humanities who are using the phrase find the concept of the articulation of a particular year, based on a deposit in a particular lake, a ridiculous way of framing the concept of a human-altered planet.”

Jacquelyn Gill, a palaeoecologist at the University of Maine in Orono, agrees. “It’s a term that belongs to everyone. To people working in philosophy and literary criticism, in the arts, in the humanities, the sciences,” she says. “I think it’s far more meaningful in the way that it is currently being used, than in any attempts that stratigraphers could have made to restrict or define it in some narrow sense.”

She adds: “It serves humanity best as a loose concept that we can use to define something that we all widely understand, which is that we live in an era where humans are the dominant force on ecological and geological processes.”

Capturing human influences

The idea of the Anthropocene is especially helpful to make clear that humans have been shaping the planet for thousands of years, and that not all of those changes have been bad, Gill says. “We could do a better job of thinking about human–environment relationships in ways that are not inherently negative all the time,” she says. “People are not a monolith, and neither are our attitudes or relationships to nature.”

Some 80% of biodiversity is currently stewarded on Indigenous lands, Gill points out. “Which should tell you something, right? That it’s not the presence of people that’s the problem,” she says. “The solution to those problems is changing the way that many dominant cultures relate to the natural world.”

The concept of the Anthropocene is owned by many fields, Gill says. “This reiterates the importance of understanding that the role of people on our planet requires many different ways of knowing and many different disciplines.”

In a world in which the threat of climate change dominates environmental debates, the term Anthropocene can help to broaden the discussion, says Yadvinder Malhi, a biodiversity researcher at the University of Oxford, UK.

“I use it all the time. For me, it captures the time where human influence has a global planetary effect, and it’s multidimensional. It’s much more than just climate change,” he says. “It’s what we’re doing. The oceans, the resources we are extracting, habitats changing.”

He adds: “I need that term when I’m trying to capture this idea of humans affecting the planet in multiple ways because of the size of our activity.”

The looseness of the term is popular, but would a formal definition help in any way? Malhi thinks it would. “There’s no other term available that captures the global multidimensional impacts on the planet,” he says. “But there is a problem in not having a formal definition if people are using it in different terms, in different ways.”

Although the word ‘Anthropocene’ makes some researchers think of processes that began 10,000 years ago, others consider it to mean those of the past century. “I think a formal adoption, like a definition, would actually help to clarify that.”

doi: https://doi.org/10.1038/d41586-024-00786-2

The Anthropocene is dead. Long live the Anthropocene (Science)

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Panel rejects a proposed geologic time division reflecting human influence, but the concept is here to stay

Original article

5 MAR 2024 – 4:00 PM ET

BY PAUL VOOSEN

A mushroom cloud rises in the night sky
A 1953 nuclear weapons test in Nevada was among the human activities that could have marked the Anthropocene. NNSA/NEVADA FIELD OFFICE/SCIENCE SOURCE

For now, we’re still in the Holocene.

Science has confirmed that a panel of two dozen geologists has voted down a proposal to end the Holocene—our current span of geologic time, which began 11,700 years ago at the end of the last ice age—and inaugurate a new epoch, the Anthropocene. Starting in the 1950s, it would have marked a time when humanity’s influence on the planet became overwhelming. The vote, first reported by The New York Times, is a stunning—though not unexpected—rebuke for the proposal, which has been working its way through a formal approval process for more than a decade.

“The decision is definitive,” says Philip Gibbard, a geologist at the University of Cambridge who is on the panel and serves as secretary-general of the International Commission on Stratigraphy (ICS), the body that governs the geologic timescale. “There are no outstanding issues to be resolved. Case closed.”

The leaders of the Anthropocene Working Group (AWG), which developed the proposal for consideration by ICS’s Subcommission on Quaternary Stratigraphy, are not yet ready to admit defeat. They note that the online tally, in which 12 out of 18 subcommission members voted against the proposal, was leaked to the press without approval of the panel’s chair. “There remain several issues that need to be resolved about the validity of the vote and the circumstances surrounding it,” says Colin Waters, a geologist at the University of Leicester who chaired AWG.

Few opponents of the Anthropocene proposal doubted the enormous impact that human influence, including climate change, is having on the planet. But some felt the proposed marker of the epoch—some 10 centimeters of mud from Canada’s Crawford Lake that captures the global surge in fossil fuel burning, fertilizer use, and atomic bomb fallout that began in the 1950s—isn’t definitive enough.

Others questioned whether it’s even possible to affix one date to the start of humanity’s broad planetary influence: Why not the rise of agriculture? Why not the vast changes that followed European encroachment on the New World? “The Anthropocene epoch was never deep enough to understand human transformation of this planet,” says Erle Ellis, a geographer at the University of Maryland, Baltimore County who resigned last year in protest from AWG.

Opponents also felt AWG made too many announcements to the press over the years while being slow to submit a proposal to the subcommission. “The Anthropocene epoch was pushed through the media from the beginning—a publicity drive,” says Stanley Finney, a stratigrapher at California State University Long Beach and head of the International Union of Geological Sciences, which would have had final approval of the proposal.

Finney also complains that from the start, AWG was determined to secure an “epoch” categorization, and ignored or countered proposals for a less formal Anthropocene designation. If they had only made their formal proposal sooner, they could have avoided much lost time, Finney adds. “It would have been rejected 10 years earlier if they had not avoided presenting it to the stratigraphic community for careful consideration.”

The Anthropocene backers will now have to wait for a decade before their proposal can be considered again. ICS has long instituted this mandatory cooling-off period, given how furious debates can turn, for example, over the boundary between the Pliocene and Pleistocene, and whether the Quaternary—our current geologic period, a category above epochs—should exist at all.

Even if it is not formally recognized by geologists, the Anthropocene is here to stay. It is used in art exhibits, journal titles, and endless books. And Gibbard, Ellis, and others have advanced the view that it can remain an informal geologic term, calling it the “Anthropocene event.” Like the Great Oxygenation Event, in which cyanobacteria flushed the atmosphere with oxygen billions of years ago, the Anthropocene marks a huge transition, but one without an exact date. “Let us work together to ensure the creation of a far deeper and more inclusive Anthropocene event,” Ellis says.

Waters and his colleagues will continue to press that the Anthropocene is worthy of recognition in the geologic timescale, even if that advocacy has to continue in an informal capacity, he says. Although small in size, Anthropocene strata such as the 10 centimeters of lake mud are distinct and can be traced using more than 100 durable geochemical signals, he says. And there is no going back to where the planet was 100 years ago, he says. “The Earth system changes that mark the Anthropocene are collectively irreversible.”

doi: 10.1126/science.z3wcw7b

Are We in the ‘Anthropocene,’ the Human Age? Nope, Scientists Say. (New York Times)

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A panel of experts voted down a proposal to officially declare the start of a new interval of geologic time, one defined by humanity’s changes to the planet.

Four people standing on the deck of a ship face a large, white mushroom cloud in the distance.
In weighing their decision, scientists considered the effect on the world of nuclear activity. A 1946 test blast over Bikini atoll. Credit: Jack Rice/Associated Press

Original article

By Raymond Zhong

March 5, 2024

The Triassic was the dawn of the dinosaurs. The Paleogene saw the rise of mammals. The Pleistocene included the last ice ages.

Is it time to mark humankind’s transformation of the planet with its own chapter in Earth history, the “Anthropocene,” or the human age?

Not yet, scientists have decided, after a debate that has spanned nearly 15 years. Or the blink of an eye, depending on how you look at it.

A committee of roughly two dozen scholars has, by a large majority, voted down a proposal to declare the start of the Anthropocene, a newly created epoch of geologic time, according to an internal announcement of the voting results seen by The New York Times.

By geologists’ current timeline of Earth’s 4.6-billion-year history, our world right now is in the Holocene, which began 11,700 years ago with the most recent retreat of the great glaciers. Amending the chronology to say we had moved on to the Anthropocene would represent an acknowledgment that recent, human-induced changes to geological conditions had been profound enough to bring the Holocene to a close.

The declaration would shape terminology in textbooks, research articles and museums worldwide. It would guide scientists in their understanding of our still-unfolding present for generations, perhaps even millenniums, to come.

In the end, though, the members of the committee that voted on the Anthropocene over the past month were not only weighing how consequential this period had been for the planet. They also had to consider when, precisely, it began.

By the definition that an earlier panel of experts spent nearly a decade and a half debating and crafting, the Anthropocene started in the mid-20th century, when nuclear bomb tests scattered radioactive fallout across our world. To several members of the scientific committee that considered the panel’s proposal in recent weeks, this definition was too limited, too awkwardly recent, to be a fitting signpost of Homo sapiens’s reshaping of planet Earth.

“It constrains, it confines, it narrows down the whole importance of the Anthropocene,” said Jan A. Piotrowski, a committee member and geologist at Aarhus University in Denmark. “What was going on during the onset of agriculture? How about the Industrial Revolution? How about the colonizing of the Americas, of Australia?”

“Human impact goes much deeper into geological time,” said another committee member, Mike Walker, an earth scientist and professor emeritus at the University of Wales Trinity Saint David. “If we ignore that, we are ignoring the true impact, the real impact, that humans have on our planet.”

Hours after the voting results were circulated within the committee early Tuesday, some members said they were surprised at the margin of votes against the Anthropocene proposal compared with those in favor: 12 to four, with two abstentions. (Another three committee members neither voted nor formally abstained.)

Even so, it was unclear on Tuesday whether the results stood as a conclusive rejection or whether they might still be challenged or appealed. In an email to The Times, the committee’s chair, Jan A. Zalasiewicz, said there were “some procedural issues to consider” but declined to discuss them further. Dr. Zalasiewicz, a geologist at the University of Leicester, has expressed support for canonizing the Anthropocene.

This question of how to situate our time in the narrative arc of Earth history has thrust the rarefied world of geological timekeepers into an unfamiliar limelight.

The grandly named chapters of our planet’s history are governed by a body of scientists, the International Union of Geological Sciences. The organization uses rigorous criteria to decide when each chapter started and which characteristics defined it. The aim is to uphold common global standards for expressing the planet’s history.

A man stands next to a machine with tubing and lines of plastic that end up in a shallow pool of water.
Polyethylene being extruded and fed into a cooling bath during plastics manufacture, circa 1950. Credit: Hulton Archive, via Getty Images

Geoscientists don’t deny our era stands out within that long history. Radionuclides from nuclear tests. Plastics and industrial ash. Concrete and metal pollutants. Rapid greenhouse warming. Sharply increased species extinctions. These and other products of modern civilization are leaving unmistakable remnants in the mineral record, particularly since the mid-20th century.

Still, to qualify for its own entry on the geologic time scale, the Anthropocene would have to be defined in a very particular way, one that would meet the needs of geologists and not necessarily those of the anthropologists, artists and others who are already using the term.

That’s why several experts who have voiced skepticism about enshrining the Anthropocene emphasized that the vote against it shouldn’t be read as a referendum among scientists on the broad state of the Earth. “This was a narrow, technical matter for geologists, for the most part,” said one of those skeptics, Erle C. Ellis, an environmental scientist at the University of Maryland, Baltimore County. “This has nothing to do with the evidence that people are changing the planet,” Dr. Ellis said. “The evidence just keeps growing.”

Francine M.G. McCarthy, a micropaleontologist at Brock University in St. Catharines, Ontario, is the opposite of a skeptic: She helped lead some of the research to support ratifying the new epoch.

“We are in the Anthropocene, irrespective of a line on the time scale,” Dr. McCarthy said. “And behaving accordingly is our only path forward.”

The Anthropocene proposal got its start in 2009, when a working group was convened to investigate whether recent planetary changes merited a place on the geologic timeline. After years of deliberation, the group, which came to include Dr. McCarthy, Dr. Ellis and some three dozen others, decided that they did. The group also decided that the best start date for the new period was around 1950.

The group then had to choose a physical site that would most clearly show a definitive break between the Holocene and the Anthropocene. They settled on Crawford Lake, in Ontario, where the deep waters have preserved detailed records of geochemical change within the sediments at the bottom.

Last fall, the working group submitted its Anthropocene proposal to the first of three governing committees under the International Union of Geological Sciences. Sixty percent of each committee has to approve the proposal for it to advance to the next.

The members of the first one, the Subcommission on Quaternary Stratigraphy, submitted their votes starting in early February. (Stratigraphy is the branch of geology concerned with rock layers and how they relate in time. The Quaternary is the ongoing geologic period that began 2.6 million years ago.)

Under the rules of stratigraphy, each interval of Earth time needs a clear, objective starting point, one that applies worldwide. The Anthropocene working group proposed the mid-20th century because it bracketed the postwar explosion of economic growth, globalization, urbanization and energy use. But several members of the subcommission said humankind’s upending of Earth was a far more sprawling story, one that might not even have a single start date across every part of the planet.

Two cooling towers, a square building and a larger building behind it with smokestacks and industrial staircases on the outside.
The world’s first full-scale atomic power station in Britain in 1956. Credit: Hulton Archive, via Getty Images

This is why Dr. Walker, Dr. Piotrowski and others prefer to describe the Anthropocene as an “event,” not an “epoch.” In the language of geology, events are a looser term. They don’t appear on the official timeline, and no committees need to approve their start dates.

Yet many of the planet’s most significant happenings are called events, including mass extinctions, rapid expansions of biodiversity and the filling of Earth’s skies with oxygen 2.1 to 2.4 billion years ago.

Even if the subcommission’s vote is upheld and the Anthropocene proposal is rebuffed, the new epoch could still be added to the timeline at some later point. It would, however, have to go through the whole process of discussion and voting all over again.

Time will march on. Evidence of our civilization’s effects on Earth will continue accumulating in the rocks. The task of interpreting what it all means, and how it fits into the grand sweep of history, might fall to the future inheritors of our world.

“Our impact is here to stay and to be recognizable in the future in the geological record — there is absolutely no question about this,” Dr. Piotrowski said. “It will be up to the people that will be coming after us to decide how to rank it.”

Raymond Zhong reports on climate and environmental issues for The Times.

Latest News on Climate Change and the Environment

Protecting groundwater. After years of decline in the nation’s groundwater, a series of developments indicate that U.S. state and federal officials may begin tightening protections for the dwindling resource. In Nevada, Idaho and Montana, court decisions have strengthened states’ ability to restrict overpumping. California is considering penalizing officials for draining aquifers. And the White House has asked scientists to advise how the federal government can help.

Weather-related disasters. An estimated 2.5 million people were forced from their homes in the United States by weather-related disasters in 2023, according to new data from the Census Bureau. The numbers paint a more complete picture than ever before of the lives of people affected by such events as climate change supercharges extreme weather.

Amazon rainforest. Up to half of the Amazon rainforest could transform into grasslands or weakened ecosystems in the coming decades, a new study found, as climate change, deforestation and severe droughts damage huge areas beyond their ability to recover. Those stresses in the most vulnerable parts of the rainforest could eventually drive the entire forest ecosystem past a tipping point that would trigger a forest-wide collapse, researchers said.

A significant threshold. Over the past 12 months, the average temperature worldwide was more than 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, higher than it was at the dawn of the industrial age. That number carries special significance, as nations agreed under the 2015 Paris Agreement to try to keep the difference between average temperatures today and in preindustrial times to 1.5 degrees Celsius, or at least below 2 degrees Celsius.

New highs. The exceptional warmth that first enveloped the planet last summer is continuing strong into 2024: Last month clocked in as the hottest January ever measured, and the hottest January on record for the oceans, too. Sea surface temperatures were just slightly lower than in August 2023, the oceans’ warmest month on the books.

Polémica con el Antropoceno: la humanidad todavía no sabe en qué época geológica vive (El País)

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elpais.com

Un comité de expertos ha tumbado la propuesta de declarar un nuevo momento geológico, pero el propio presidente denuncia irregularidades en la votación

Manuel Ansede

Madrid –

Extracción de un testigo de sedimentos del fondo del lago Crawford, a las afueras de Toronto (Canadá). TIM PATTERSON / UNIVERSIDAD DE CARLETON

La idea del Antropoceno —que la humanidad vive desde 1950 en una nueva época geológica caracterizada por la contaminación humana— se ha hecho tan popular en los últimos años que hasta la Real Academia Española adoptó el término en el Diccionario de la Lengua en 2021. Los académicos se dieron esta vez demasiada prisa. El concepto sigue en el aire, en medio de una vehemente polémica entre especialistas. Miembros del comité de expertos que debe tomar la decisión en la Unión Internacional de Ciencias Geológicas (UICG) —la Subcomisión de Estratigrafía del Cuaternario— han filtrado este martes al diario The New York Times que han votado mayoritariamente en contra de reconocer la existencia del Antropoceno. Sin embargo, el presidente de la Subcomisión, el geólogo Jan Zalasiewicz, explica a EL PAÍS que el resultado preliminar de la votación se ha anunciado sin su autorización y que todavía quedan “algunos asuntos pendientes con los votos que hay que resolver”. La humanidad todavía no sabe en qué época geológica vive.

El químico holandés Paul Crutzen, ganador del Nobel de Química por iluminar el agujero de la capa de ozono, planteó en el año 2000 que el planeta había entrado en una nueva época, provocada por el impacto brutal de los seres humanos. Un equipo internacional de especialistas, el Grupo de Trabajo del Antropoceno, ha analizado los hechos científicos desde 2009 y el año pasado presentó una propuesta para proclamar oficialmente esta nueva época geológica, marcada por la radiactividad de las bombas atómicas y los contaminantes procedentes de la quema de carbón y petróleo. El diminuto lago Crawford, a las afueras de Toronto (Canadá), era el lugar indicado para ejemplificar el inicio del Antropoceno, gracias a los sedimentos de su fondo, imperturbados desde hace siglos.

La mayoría de los miembros de la Subcomisión de Estratigrafía del Cuaternario de la UICG ha votado en contra de la propuesta, según el periódico estadounidense. El geólogo británico Colin Waters, líder del Grupo de Trabajo del Antropoceno, explica a EL PAÍS que se ha enterado por la prensa. “Todavía no hemos recibido una confirmación oficial directamente del secretario de la Subcomisión de Estratigrafía del Cuaternario. Parece que The New York Times recibe los resultados antes que nosotros, es muy decepcionante”, lamenta Waters.

El geólogo reconoce que el dictamen, si se confirma, sería el fin de su propuesta actual, pero no se rinde. “Tenemos muchos investigadores eminentes que desean continuar como grupo, de manera informal, defendiendo las evidencias de que el Antropoceno debería ser formalizado como una época”, afirma. A su juicio, los estratos geológicos actuales —contaminados por isótopos radiactivos, microplásticos, cenizas y pesticidas— han cambiado de manera irreversible respecto a los del Holoceno, la época geológica iniciada hace más de 10.000 años, tras la última glaciación. “Dadas las pruebas existentes, que siguen aumentando, no me sorprendería un futuro llamamiento a reconsiderar nuestra propuesta”, opina Waters, de la Universidad de Leicester.

El jefe del Grupo de Trabajo del Antropoceno sostiene que hay “algunas cuestiones de procedimiento” que ponen en duda la validez de la votación. La geóloga italiana Silvia Peppoloni, jefa de la Comisión de Geoética de la UICG, confirma que su equipo ha realizado un informe sobre esta pelea entre la Subcomisión de Estratigrafía del Cuaternario y el Grupo de Trabajo del Antropoceno. El documento está sobre la mesa del presidente de la UICG, el británico John Ludden.

La geóloga canadiense Francine McCarthy estaba convencida de que el lago Crawford convencería a los escépticos. Desde fuera parece pequeño, con apenas 250 metros de largo, pero su profundidad roza los 25 metros. Sus aguas superficiales no se mezclan con las de su lecho, por lo que el suelo del fondo se puede analizar como una lasaña, en la que cada capa acumula sedimentos procedentes de la atmósfera. Ese calendario subacuático del lago Crawford revela la denominada Gran Aceleración, el momento alrededor de 1950 en el que la humanidad empezó a dejar una huella cada vez más evidente, con el lanzamiento de bombas atómicas, la quema masiva de petróleo y carbón y la extinción de especies.

“Ignorar el enorme impacto de los humanos en nuestro planeta desde mediados del siglo XX tiene potencialmente consecuencias dañinas, al minimizar la importancia de los datos científicos para hacer frente al evidente cambio en el sistema de la Tierra, como ya señaló Paul Crutzen hace casi 25 años”, advierte McCarthy.

Em votação, cientistas negam que estejamos no Antropoceno, a época geológica dos humanos (Folha de S.Paulo)

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Grupo rejeitou que mudanças sejam profundas o bastante para encerrar o Holoceno

Raymond Zhong

5 de março de 2024

O Triássico foi o amanhecer dos dinossauros. O Paleogeno viu a ascensão dos mamíferos. O Pleistoceno incluiu as últimas eras glaciais.

Está na hora de marcar a transformação da humanidade no planeta com seu próprio capítulo na história da Terra, o “Antropoceno”, ou a época humana?

Ainda não, decidiram os cientistas, após um debate que durou quase 15 anos. Ou um piscar de olhos, dependendo do ângulo pelo qual você olha.

Um comitê de cerca de duas dezenas de estudiosos votou, em grande maioria, contra uma proposta de declarar o início do Antropoceno, uma época recém-criada do tempo geológico, de acordo com um anúncio interno dos resultados da votação visto pelo The New York Times.

Pela linha do tempo atual dos geólogos da história de 4,6 bilhões de anos da Terra, nosso mundo agora está no Holoceno, que começou há 11,7 mil anos com o recuo mais recente dos grandes glaciares.

Alterar a cronologia para dizer que avançamos para o Antropoceno representaria um reconhecimento de que as mudanças recentes induzidas pelo homem nas condições geológicas foram profundas o suficiente para encerrar o Holoceno.

A declaração moldaria a terminologia em livros didáticos, artigos de pesquisa e museus em todo o mundo. Orientaria os cientistas em sua compreensão do nosso presente ainda em desenvolvimento por gerações, talvez até por milênios.

No fim das contas, porém, os membros do comitê que votaram sobre o Antropoceno nas últimas semanas não estavam apenas considerando o quão determinante esse período havia sido para o planeta. Eles também tiveram que considerar quando, precisamente, ele começou.

Pela definição que um painel anterior de especialistas passou quase uma década e meia debatendo e elaborando, o Antropoceno começou na metade do século 20, quando testes de bombas nucleares espalharam material radioativo por todo o nosso mundo.

Para vários membros do comitê científico que avaliaram a proposta do painel nas últimas semanas, essa definição era muito limitada, muito recente e inadequada para ser um marco adequado da remodelação do Homo sapiens no planeta Terra.

“Isso restringe, confina, estreita toda a importância do Antropoceno”, disse Jan A. Piotrowski, membro do comitê e geólogo da Universidade de Aarhus, na Dinamarca. “O que estava acontecendo durante o início da agricultura? E a Revolução Industrial? E a colonização das Américas, da Austrália?”

“O impacto humano vai muito mais fundo no tempo geológico”, disse outro membro do comitê, Mike Walker, cientista da Terra e professor emérito da Universidade de Gales Trinity Saint David. “Se ignorarmos isso, estamos ignorando o verdadeiro impacto que os humanos têm em nosso planeta.”

Horas após a circulação dos resultados da votação dentro do comitê nesta terça-feira (5) de manhã, alguns membros disseram que ficaram surpresos com a margem de votos contra a proposta do Antropoceno em comparação com os a favor: 12 a 4, com 2 abstenções.

Mesmo assim, nesta terça de manhã não ficou claro se os resultados representavam uma rejeição conclusiva ou se ainda poderiam ser contestados ou apelados. Em um e-mail para o Times, o presidente do comitê, Jan A. Zalasiewicz, disse que havia “algumas questões procedimentais a considerar”, mas se recusou a discuti-las mais a fundo.

Zalasiewicz, geólogo da Universidade de Leicester, expressou apoio à canonização do Antropoceno.

Essa questão de como situar nosso tempo na narrativa da história da Terra colocou o mundo dos guardiões do tempo geológico sob uma luz desconhecida.

Os capítulos grandiosamente nomeados da história de nosso planeta são governados por um grupo de cientistas, a União Internacional de Ciências Geológicas. A organização usa critérios rigorosos para decidir quando cada capítulo começou e quais características o definiram. O objetivo é manter padrões globais comuns para expressar a história do planeta.

Os geocientistas não negam que nossa era se destaca dentro dessa longa história. Radionuclídeos de testes nucleares. Plásticos e cinzas industriais. Poluentes de concreto e metal. Aquecimento global rápido. Aumento acentuado de extinções de espécies. Esses e outros produtos da civilização moderna estão deixando vestígios inconfundíveis no registro mineral, especialmente desde meados do século 20.

Ainda assim, para se qualificar para a entrada na escala de tempo geológico, o Antropoceno teria que ser definido de uma maneira muito específica, que atendesse às necessidades dos geólogos e não necessariamente dos antropólogos, artistas e outros que já estão usando o termo.

Por isso, vários especialistas que expressaram ceticismo quanto à consagração do Antropoceno enfatizaram que o voto contra não deve ser interpretado como um referendo entre cientistas sobre o amplo estado da Terra.

“Este é um assunto específico e técnico para os geólogos, em sua maioria”, disse um desses céticos, Erle C. Ellis, um cientista ambiental da Universidade de Maryland. “Isso não tem nada a ver com a evidência de que as pessoas estão mudando o planeta”, afirmou Ellis. “A evidência continua crescendo.”

Francine M.G. McCarthy, micropaleontóloga da Universidade Brock em St. Catharines, Ontário (Canadá), é tem visão oposta: ela ajudou a liderar algumas das pesquisas para apoiar a ratificação da nova época.

“Estamos no Antropoceno, independentemente de uma linha na escala de tempo”, disse McCarthy. “E agir de acordo é o nosso único caminho a seguir.”

A proposta do Antropoceno teve início em 2009, quando um grupo de trabalho foi convocado para investigar se as recentes mudanças planetárias mereciam um lugar na linha do tempo geológica.

Após anos de deliberação, o grupo, que passou a incluir McCarthy, Ellis e cerca de três dezenas de outros, decidiu que sim. O grupo também decidiu que a melhor data de início para o novo período era por volta de 1950.

O grupo então teve que escolher um local físico que mostrasse de forma mais clara uma quebra definitiva entre o Holoceno e o Antropoceno. Eles escolheram o Lago Crawford, em Ontário, no Canadá, onde as águas profundas preservaram registros detalhados de mudanças geoquímicas nos sedimentos do fundo.

No outono passado, o grupo de trabalho enviou sua proposta do Antropoceno para o primeiro dos três comitês governantes da União Internacional de Ciências Geológicas —60% de cada comitê precisam aprovar a proposta para que ela avance para o próximo.

Os membros do primeiro comitê, a Subcomissão de Estratigrafia do Quaternário, enviaram seus votos a partir do início de fevereiro. (Estratigrafia é o ramo da geologia que se dedica ao estudo das camadas de rocha e como elas se relacionam no tempo. O Quaternário é o período geológico em curso que começou há 2,6 milhões de anos.)

De acordo com as regras da estratigrafia, cada intervalo de tempo da Terra precisa de um ponto de partida claro e objetivo, que se aplique em todo o mundo. O grupo de trabalho do Antropoceno propôs meados do século 20 porque isso abrangia a explosão do crescimento econômico pós-guerra, a globalização, a urbanização e o uso de energia.

Mas vários membros da subcomissão disseram que a transformação da humanidade na Terra era uma história muito mais abrangente, que talvez nem tenha uma única data de início em todas as partes do planeta.

Por isso, Walker, Piotrowski e outros preferem descrever o Antropoceno como um “evento”, não como uma “época”. Na linguagem da geologia, eventos são um termo mais amplo. Eles não aparecem na linha do tempo oficial, e nenhum comitê precisa aprovar suas datas de início.

No entanto, muitos dos acontecimentos mais significativos do planeta são chamados de eventos, incluindo extinções em massa, expansões rápidas da biodiversidade e o preenchimento dos céus da Terra com oxigênio há 2,1 bilhões a 2,4 bilhões de anos.

Mesmo que o voto da subcomissão seja mantido e a proposta do Antropoceno seja rejeitada, a nova época ainda poderá ser adicionada à linha do tempo em algum momento posterior. No entanto, terá que passar por todo o processo de discussão e votação novamente.