Arquivo da tag: Elevação do nível dos oceanos

Climate change could trigger strong sea level rise (Science Daily)

International research team presents findings from frozen ‘climate archive’ of Antarctica

Date:
January 5, 2017
Source:
University of Bonn
Summary:
About 15,000 years ago, the ocean around Antarctica has seen an abrupt sea level rise of several meters. It could happen again.

Iceberg in the southeastern Weddell Sea region. Credit: Photo: Dr. Michael Weber

About 15,000 years ago, the ocean around Antarctica has seen an abrupt sea level rise of several meters. It could happen again. An international team of scientists with the participation of the University of Bonn is now reporting its findings in the magazine Scientific Reports.

University of Bonn’s climate researcher Michael E. Weber is a member of the study group. He says, “The changes that are currently taking place in a disturbing manner resemble those 14,700 years ago.” At that time, changes in atmospheric-oceanic circulation led to a stratification in the ocean with a cold layer at the surface and a warm layer below. Under such conditions, ice sheets melt more strongly than when the surrounding ocean is thoroughly mixed. This is exactly what is presently happening around the Antarctic.

The main author of the study, the Australian climate researcher Chris Fogwill from the Climate Change Research Center in Sydney, explains the process as follows: “The reason for the layering is that global warming in parts of Antarctica is causing land based ice to melt, adding massive amounts of freshwater to the ocean surface. At the same time as the surface is cooling, the deeper ocean is warming, which has already accelerated the decline of glaciers in the Amundsen Sea Embayment.” It appears global warming is replicating conditions that, in the past, triggered significant shifts in the stability of the Antarctic ice sheet.

To investigate the climate changes of the past, the scientists are studying drill cores from the eternal ice. Layer by layer, this frozen “climate archive” reveals its secrets to the experts. In previous studies, the scientists had found evidence of eight massive melting events in deep sea sediments around the Antarctic, which occurred at the transition from the last ice age to the present warm period. Co-author Dr. Weber from the Steinmann Institute of the University of Bonn says: “The largest melt occurred 14,700 years ago. During this time the Antarctic contributed to a sea level rise of at least three meters within a few centuries.”

The present discovery is the first direct evidence from the Antarctic continent which confirms the assumed models. The research team used isotopic analyzes of ice cores from the Weddell Sea region, which now flows into the ocean about a quarter of the Antarctic melt.

Through a combination with ice sheet and climate modeling, the isotopic data show that the waters around the Antarctic were heavily layered at the time of the melting events, so that the ice sheets melted at a faster rate. “The big question is whether the ice sheet will react to these changing ocean conditions as rapidly as it did 14,700 years ago,” says co-author Nick Golledge from the Antarctic Research Center in Wellington, New Zealand.


Journal Reference:

  1. C. J. Fogwill, C. S. M. Turney, N. R. Golledge, D. M. Etheridge, M. Rubino, D. P. Thornton, A. Baker, J. Woodward, K. Winter, T. D. van Ommen, A. D. Moy, M. A. J. Curran, S. M. Davies, M. E. Weber, M. I. Bird, N. C. Munksgaard, L. Menviel, C. M. Rootes, B. Ellis, H. Millman, J. Vohra, A. Rivera, A. Cooper. Antarctic ice sheet discharge driven by atmosphere-ocean feedbacks at the Last Glacial TerminationScientific Reports, 2017; 7: 39979 DOI: 10.1038/srep39979

Climate Seer James Hansen Issues His Direst Forecast Yet (The Daily Beast) + other sources, and repercussions

A polar bear walks in the snow near the Hudson Bay waiting for the bay to freeze, 13 November 2007, outside Churchill, Mantioba, Canada. Polar bears return to Churchill, the polar bear capital of the world, to hunt for seals on the icepack every year at this time and remain on the icepack feeding on seals until the spring thaw.   AFP PHOTO/Paul J. Richards (Photo credit should read PAUL J. RICHARDS/AFP/Getty Images)

Paul J Richards/AFP/Getty

Mark Hertsgaard 

07.20.151:00 AM ET

James Hansen’s new study explodes conventional goals of climate diplomacy and warns of 10 feet of sea level rise before 2100. The good news is, we can fix it.

James Hansen, the former NASA scientist whose congressional testimony put global warming on the world’s agenda a quarter-century ago, is now warning that humanity could confront “sea level rise of several meters” before the end of the century unless greenhouse gas emissions are slashed much faster than currently contemplated.This roughly 10 feet of sea level rise—well beyond previous estimates—would render coastal cities such as New York, London, and Shanghai uninhabitable.  “Parts of [our coastal cities] would still be sticking above the water,” Hansen says, “but you couldn’t live there.”

James Hanson

Columbia University

This apocalyptic scenario illustrates why the goal of limiting temperature rise to 2 degrees Celsius is not the safe “guardrail” most politicians and media coverage imply it is, argue Hansen and 16 colleagues in a blockbuster study they are publishing this week in the peer-reviewed journal Atmospheric Chemistry and Physics. On the contrary, a 2 C future would be “highly dangerous.”

If Hansen is right—and he has been right, sooner, about the big issues in climate science longer than anyone—the implications are vast and profound.

Physically, Hansen’s findings mean that Earth’s ice is melting and its seas are rising much faster than expected. Other scientists have offered less extreme findings; the United Nations Intergovernmental Panel on Climate Change (IPCC) has projected closer to 3 feet of sea level rise by the end of the century, an amount experts say will be difficult enough to cope with. (Three feet of sea level rise would put runways of all three New York City-area airports underwater unless protective barriers were erected. The same holds for airports in the San Francisco Bay Area.)

Worldwide, approximately $3 trillion worth infrastructure vital to civilization such as water treatment plants, power stations, and highways are located at or below 3 feet of sea level, according to the Stern Review, a comprehensive analysis published by the British government.

Hansen’s track record commands respect. From the time the soft-spoken Iowan told the U.S. Senate in 1988 that man-made global warming was no longer a theory but had in fact begun and threatened unparalleled disaster, he has consistently been ahead of the scientific curve.

Hansen has long suspected that computer models underestimated how sensitive Earth’s ice sheets were to rising temperatures. Indeed, the IPCC excluded ice sheet melt altogether from its calculations of sea level rise. For their study, Hansen and his colleagues combined ancient paleo-climate data with new satellite readings and an improved model of the climate system to demonstrate that ice sheets can melt at a “non-linear” rate: rather than an incremental melting as Earth’s poles inexorably warm, ice sheets might melt at exponential rates, shedding dangerous amounts of mass in a matter of decades, not millennia. In fact, current observations indicate that some ice sheets already are melting this rapidly.

“Prior to this paper I suspected that to be the case,” Hansen told The Daily Beast. “Now we have evidence to make that statement based on much more than suspicion.”

The Nature Climate Change study and Hansen’s new paper give credence to the many developing nations and climate justice advocates who have called for more ambitious action.

Politically, Hansen’s new projections amount to a huge headache for diplomats, activists, and anyone else hoping that a much-anticipated global climate summit the United Nations is convening in Paris in December will put the world on a safe path. President Barack Obama and other world leaders must now reckon with the possibility that the 2 degrees goal they affirmed at the Copenhagen summit in 2009 is actually a recipe for catastrophe. In effect, Hansen’s study explodes what has long been the goal of conventional climate diplomacy.

More troubling, honoring even the conventional 2 degrees C target has so far proven extremely challenging on political and economic grounds. Current emission trajectories put the world on track towards a staggering 4 degrees of warming before the end of the century, an amount almost certainly beyond civilization’s coping capacity. In preparation for the Paris summit, governments have begun announcing commitments to reduce emissions, but to date these commitments are falling well short of satisfying the 2 degrees goal. Now, factor in the possibility that even 2 degrees is too much and many negotiators may be tempted to throw up their hands in despair.

They shouldn’t. New climate science brings good news as well as bad.  Humanity can limit temperature rise to 1.5 degrees C if it so chooses, according to a little-noticed study by experts at the Potsdam Institute for Climate Impacts (now perhaps the world’s foremost climate research center) and the International Institute for Applied Systems Analysis published in Nature Climate Change in May.

“Actions for returning global warming to below 1.5 degrees Celsius by 2100 are in many ways similar to those limiting warming to below 2 degrees Celsius,” said Joeri Rogelj, a lead author of the study. “However … emission reductions need to scale up swiftly in the next decades.” And there’s a significant catch: Even this relatively optimistic study concludes that it’s too late to prevent global temperature rising by 2 degrees C. But this overshoot of the 2 C target can be made temporary, the study argues; the total increase can be brought back down to 1.5 C later in the century.

Besides the faster emissions reductions Rogelj referenced, two additional tools are essential, the study outlines. Energy efficiency—shifting to less wasteful lighting, appliances, vehicles, building materials and the like—is already the cheapest, fastest way to reduce emissions. Improved efficiency has made great progress in recent years but will have to accelerate, especially in emerging economies such as China and India.

Also necessary will be breakthroughs in so-called “carbon negative” technologies. Call it the photosynthesis option: because plants inhale carbon dioxide and store it in their roots, stems, and leaves, one can remove carbon from the atmosphere by growing trees, planting cover crops, burying charred plant materials underground, and other kindred methods. In effect, carbon negative technologies can turn back the clock on global warming, making the aforementioned descent from the 2 C overshoot to the 1.5 C goal later in this century theoretically possible. Carbon-negative technologies thus far remain unproven at the scale needed, however; more research and deployment is required, according to the study.

Together, the Nature Climate Change study and Hansen’s new paper give credence to the many developing nations and climate justice advocates who have called for more ambitious action. The authors of the Nature Climate Changestudy point out that the 1.5 degrees goal “is supported by more than 100 countries worldwide, including those most vulnerable to climate change.” In May, the governments of 20 of those countries, including the Philippines, Costa Rica, Kenya, and Bangladesh, declared the 2 degrees target “inadequate” and called for governments to “reconsider” it in Paris.

Hansen too is confident that the world “could actually come in well under 2 degrees, if we make the price of fossil fuels honest.”

That means making the market price of gasoline and other products derived from fossil fuels reflect the enormous costs that burning those fuels currently externalizes onto society as a whole. Economists from left to right have advocated achieving this by putting a rising fee or tax on fossil fuels. This would give businesses, governments, and other consumers an incentive to shift to non-carbon fuels such as solar, wind, nuclear, and, best of all, increased energy efficiency. (The cheapest and cleanest fuel is the fuel you don’t burn in the first place.)

But putting a fee on fossil fuels will raise their price to consumers, threatening individual budgets and broader economic prospects, as opponents will surely point out. Nevertheless, higher prices for carbon-based fuels need not have injurious economic effects if the fees driving those higher prices are returned to the public to spend as it wishes. It’s been done that way for years with great success in Alaska, where all residents receive an annual check in compensation for the impact the Alaskan oil pipeline has on the state.

“Tax Pollution, Pay People” is the bumper sticker summary coined by activists at the Citizens Climate Lobby. Legislation to this effect has been introduced in both houses of the U.S. Congress.

Meanwhile, there are also a host of other reasons to believe it’s not too late to preserve a livable climate for young people and future generations.

The transition away from fossil fuels has begun and is gaining speed and legitimacy. In 2014, global greenhouse gas emissions remained flat even as the world economy grew—a first. There has been a spectacular boom in wind and solar energy, including in developing countries, as their prices plummet. These technologies now qualify as a “disruptive” economic force that promises further breakthroughs, said Achim Steiner, executive director of the UN Environment Programme.

Coal, the most carbon-intensive conventional fossil fuel, is in a death spiral, partly thanks to another piece of encouraging news: the historic climate agreement the U.S. and China reached last November, which envisions both nations slashing coal consumption (as China is already doing). Hammering another nail into coal’s coffin, the leaders of Great Britain’s three main political parties pledged to phase out coal, no matter who won the general elections last May.

“If you look at the long-term [for coal], it’s not getting any better,” said Standard & Poor’s Aneesh Prabhu when S&P downgraded coal company bonds to junk status. “It’s a secular decline,” not a mere cyclical downturn.

Last but not least, a vibrant mass movement has arisen to fight climate change, most visibly manifested when hundreds of thousands of people thronged the streets of New York City last September, demanding action from global leaders gathered at the UN. The rally was impressive enough that it led oil and gas giant ExxonMobil to increase its internal estimate of how likely the U.S. government is to take strong action. “That many people marching is clearly going to put pressure on government to do something,” an ExxonMobil spokesman told Bloomberg Businessweek.

The climate challenge has long amounted to a race between the imperatives of science and the contingencies of politics. With Hansen’s paper, the science has gotten harsher, even as the Nature Climate Change study affirms that humanity can still choose life, if it will. The question now is how the politics will respond—now, at Paris in December, and beyond.

Mark Hertsgaard has reported on politics, culture, and the environment from more than 20 countries and written six books, including “HOT: Living Through the Next Fifty Years on Earth.”

*   *   *

Experts make dire prediction about sea levels (CBS)

VIDEO

In the future, there could be major flooding along every coast. So says a new study that warns the world’s seas are rising.

Ever-warming oceans that are melting polar ice could raise sea levels 15 feet in the next 50 to 100 years, NASA’s former climate chief now says. That’s five times higher than previous predictions.

“This is the biggest threat the planet faces,” said James Hansen, the co-author of the new journal article raising that alarm scenario.

“If we get sea level rise of several meters, all coastal cities become dysfunctional,” he said. “The implications of this are just incalculable.”

If ocean levels rise just 10 feet, areas like Miami, Boston, Seattle and New York City would face flooding.

The melting ice would cool ocean surfaces at the poles even more. While the overall climate continues to warm. The temperature difference would fuel even more volatile weather.

“As the atmosphere gets warmer and there’s more water vapor, that’s going to drive stronger thunderstorms, stronger hurricanes, stronger tornadoes, because they all get their energy from the water vapor,” said Hansen.

Nearly a decade ago, Hansen told “60 Minutes” we had 10 years to get global warming under control, or we would reach “tipping point.”

“It will be a situation that is out of our control,” he said. “We’re essentially at the edge of that. That’s why this year is a critical year.”

Critical because of a United Nations meeting in Paris that is designed to reach legally binding agreements on carbons emissions, those greenhouse gases that create global warming.

*   *   *

Sea Levels Could Rise Much Faster than Thought (Climate Denial Crock of the Week)

with Peter SinclairJuly 21, 2015

Washington Post:

James Hansen has often been out ahead of his scientific colleagues.

With his 1988 congressional testimony, the then-NASA scientist is credited with putting the global warming issue on the map by saying that a warming trend had already begun. “It is time to stop waffling so much and say that the evidence is pretty strong that the greenhouse effect is here,” Hansen famously testified.

Now Hansen — who retired in 2013 from his NASA post, and is currently an adjunct professor at Columbia University’s Earth Institute — is publishing what he says may be his most important paper. Along with 16 other researchers — including leading experts on the Greenland and Antarctic ice sheets — he has authored a lengthy study outlining an scenario of potentially rapid sea level rise combined with more intense storm systems.

It’s an alarming picture of where the planet could be headed — and hard to ignore, given its author. But it may also meet with considerable skepticism in the broader scientific community, given that its scenarios of sea level rise occur more rapidly than those ratified by the United Nations’ Intergovernmental Panel on Climate Change in its latest assessment of the state of climate science, published in 2013.

In the new study, Hansen and his colleagues suggest that the “doubling time” for ice loss from West Antarctica — the time period over which the amount of loss could double — could be as short as 10 years. In other words, a non-linear process could be at work, triggering major sea level rise in a time frame of 50 to 200 years. By contrast, Hansen and colleagues note, the IPCC assumed more of a linear process, suggesting only around 1 meter of sea level rise, at most, by 2100.

Here, a clip from our extended interview with Eric Rignot in December of 2014.  Rignot is one of the co-authors of the new study.

Slate:

The study—written by James Hansen, NASA’s former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields—concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. The study, which has not yet been peer reviewed, brings new importance to a feedback loop in the ocean near Antarctica that results in cooler freshwater from melting glaciers forcing warmer, saltier water underneath the ice sheets, speeding up the melting rate. Hansen, who is known for being alarmist and also right, acknowledges that his study implies change far beyond previous consensus estimates. In a conference call with reporters, he said he hoped the new findings would be “substantially more persuasive than anything previously published.” I certainly find them to be.

We conclude that continued high emissions will make multi-meter sea level rise practically unavoidable and likely to occur this century. Social disruption and economic consequences of such large sea level rise could be devastating. It is not difficult to imagine that conflicts arising from forced migrations and economic collapse might make the planet ungovernable, threatening the fabric of civilization.

The science of ice melt rates is advancing so fast, scientists have generally been reluctant to put a number to what is essentially an unpredictable, non-linear response of ice sheets to a steadily warming ocean. With Hansen’s new study, that changes in a dramatic way. One of the study’s co-authors is Eric Rignot, whose own study last year found that glacial melt from West Antarctica now appears to be “unstoppable.” Chris Mooney, writing for Mother Jonescalled that study a “holy shit” moment for the climate.

Daily Beast:

New climate science brings good news as well as bad.  Humanity can limit temperature rise to 1.5 degrees C if it so chooses, according to a little-noticed study by experts at the Potsdam Institute for Climate Impacts (now perhaps the world’s foremost climate research center) and the International Institute for Applied Systems Analysis published in Nature Climate Changein May.

shanghai500

“Actions for returning global warming to below 1.5 degrees Celsius by 2100 are in many ways similar to those limiting warming to below 2 degrees Celsius,” said Joeri Rogelj, a lead author of the study. “However … emission reductions need to scale up swiftly in the next decades.” And there’s a significant catch: Even this relatively optimistic study concludes that it’s too late to prevent global temperature rising by 2 degrees C. But this overshoot of the 2 C target can be made temporary, the study argues; the total increase can be brought back down to 1.5 C later in the century.

Besides the faster emissions reductions Rogelj referenced, two additional tools are essential, the study outlines. Energy efficiency—shifting to less wasteful lighting, appliances, vehicles, building materials and the like—is already the cheapest, fastest way to reduce emissions. Improved efficiency has made great progress in recent years but will have to accelerate, especially in emerging economies such as China and India.

Also necessary will be breakthroughs in so-called “carbon negative” technologies. Call it the photosynthesis option: because plants inhale carbon dioxide and store it in their roots, stems, and leaves, one can remove carbon from the atmosphere by growing trees, planting cover crops, burying charred plant materials underground, and other kindred methods. In effect, carbon negative technologies can turn back the clock on global warming, making the aforementioned descent from the 2 C overshoot to the 1.5 C goal later in this century theoretically possible. Carbon-negative technologies thus far remain unproven at the scale needed, however; more research and deployment is required, according to the study.

*   *   *

Earth’s Most Famous Climate Scientist Issues Bombshell Sea Level Warning (Slate)

495456719-single-family-homes-on-islands-and-condo-buildings-on

Monday’s new study greatly increases the potential for catastrophic near-term sea level rise. Here, Miami Beach, among the most vulnerable cities to sea level rise in the world. Photo by Joe Raedle/Getty Images

In what may prove to be a turning point for political action on climate change, a breathtaking new study casts extreme doubt about the near-term stability of global sea levels.

The study—written by James Hansen, NASA’s former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields—concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. The study, which has not yet been peer-reviewed, brings new importance to a feedback loop in the ocean near Antarctica that results in cooler freshwater from melting glaciers forcing warmer, saltier water underneath the ice sheets, speeding up the melting rate. Hansen, who is known for being alarmist and also right, acknowledges that his study implies change far beyond previous consensus estimates. In a conference call with reporters, he said he hoped the new findings would be “substantially more persuasive than anything previously published.” I certainly find them to be.

To come to their findings, the authors used a mixture of paleoclimate records, computer models, and observations of current rates of sea level rise, but “the real world is moving somewhat faster than the model,” Hansen says.

Hansen’s study does not attempt to predict the precise timing of the feedback loop, only that it is “likely” to occur this century. The implications are mindboggling: In the study’s likely scenario, New York City—and every other coastal city on the planet—may only have a few more decades of habitability left. That dire prediction, in Hansen’s view, requires “emergency cooperation among nations.”

We conclude that continued high emissions will make multi-meter sea level rise practically unavoidable and likely to occur this century. Social disruption and economic consequences of such large sea level rise could be devastating. It is not difficult to imagine that conflicts arising from forced migrations and economic collapse might make the planet ungovernable, threatening the fabric of civilization.

The science of ice melt rates is advancing so fast, scientists have generally been reluctant to put a number to what is essentially an unpredictable, nonlinear response of ice sheets to a steadily warming ocean. With Hansen’s new study, that changes in a dramatic way. One of the study’s co-authors is Eric Rignot, whose own study last year found that glacial melt from West Antarctica now appears to be “unstoppable.” Chris Mooney, writing for Mother Jonescalled that study a “holy shit” moment for the climate.

One necessary note of caution: Hansen’s study comes via a nontraditional publishing decision by its authors. The study will be published in Atmospheric Chemistry and Physics, an open-access “discussion” journal, and will not have formal peer review prior to its appearance online later this week. [Update, July 23: The paper is now available.] The complete discussion draft circulated to journalists was 66 pages long, and included more than 300 references. The peer review will take place in real time, with responses to the work by other scientists also published online. Hansen said this publishing timeline was necessary to make the work public as soon as possible before global negotiators meet in Paris later this year. Still, the lack of traditional peer review and the fact that this study’s results go far beyond what’s been previously published will likely bring increased scrutiny. On Twitter, Ruth Mottram, a climate scientist whose work focuses on Greenland and the Arctic, was skeptical of such enormous rates of near-term sea level rise, though she defended Hansen’s decision to publish in a nontraditional way.

In 2013, Hansen left his post at NASA to become a climate activist because, in his words, “as a government employee, you can’t testify against the government.” In a wide-ranging December 2013 study, conducted to support Our Children’s Trust, a group advancing legal challenges to lax greenhouse gas emissions policies on behalf of minors, Hansen called for a “human tipping point”—essentially, a social revolution—as one of the most effective ways of combating climate change, though he still favors a bilateral carbon tax agreed upon by the United States and China as the best near-term climate policy. In the new study, Hansen writes, “there is no morally defensible excuse to delay phase-out of fossil fuel emissions as rapidly as possible.”

Asked whether Hansen has plans to personally present the new research to world leaders, he said: “Yes, but I can’t talk about that today.” What’s still uncertain is whether, like with so many previous dire warnings, world leaders will be willing to listen.

*   *   *

Ice Melt, Sea Level Rise and Superstorms (Climate Sciences, Awareness and Solutions / Earth Institute, Columbia University)

23 July 2015

James Hansen

The paper “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2°C global warming is highly dangerous” has been published in Atmospheric Chemistry and Physics Discussion and is freely available here.

The paper draws on a large body of work by the research community, as indicated by the 300 references. No doubt we missed some important relevant contributions, which we may be able to rectify in the final version of the paper. I thank all the researchers who provided data or information, many of whom I may have failed to include in the acknowledgments, as the work for the paper occurred over a several year period.

I am especially grateful to the Durst family for a generous grant that allowed me to work full time this year on finishing the paper, as well as the other supporters of our program Climate Science, Awareness and Solutions at the Columbia University Earth Institute.

In the conceivable event that you do not read the full paper plus supplement, I include the Acknowledgments here:

Acknowledgments. Completion of this study was made possible by a generous gift from The Durst Family to the Climate Science, Awareness and Solutions program at the Columbia University Earth Institute. That program was initiated in 2013 primarily via support from the Grantham Foundation for Protection of the Environment, Jim and Krisann Miller, and Gerry Lenfest and sustained via their continuing support. Other substantial support has been provided by the Flora Family Foundation, Dennis Pence, the Skoll Global Threats Fund, Alexander Totic and Hugh Perrine. We thank Anders Carlson, Elsa Cortijo, Nil Irvali, Kurt Lambeck, Scott Lehman, and Ulysses Ninnemann for their kind provision of data and related information. Support for climate simulations was provided by the NASA High-End Computing (HEC) Program through the NASA Center for Climate Simulation (NCCS) at Goddard Space Flight Center.

Study Reveals Scary New Facts About Sea Level Rise (Climate Progress)

POSTED ON JANUARY 15, 2015 AT 11:05 AM UPDATED: JANUARY 15, 2015 AT 1:50 PM

A Sri Lankan man throws his bait as he fishes in Colombo, Sri Lanka, Monday, July 1, 2013.

A Sri Lankan man throws his bait as he fishes in Colombo, Sri Lanka, Monday, July 1, 2013.

CREDIT: AP PHOTO/ERANGA JAYAWARDENA

A new study from scientists at Harvard and Rutgers Universities has been sweeping theinternet, and for good reason: it shows, quite alarmingly, that the planet’s seas have been rising much faster than we thought.

The research can be confusing on its face. At first glance, it shows that scientists have actually been overstating the rate of sea level rise for the first 90 years of the 20th century. Instead of rising about six inches over that period of time, the Harvard and Rutgers scientists discovered that the sea actually only rose by about five inches. That’s a big overstatement — a two quadrillion gallon overstatement, in fact — enough to fill three billion Olympic-size swimming pools, the New York Times reported.

But here’s the thing. If the sea wasn’t rising as steadily as we believed from 1900 to 1990, that means that it has been rising much more quickly than we thought from 1990 to the present day. In other words, we used to think the rate of acceleration of sea level rise in the last 25 years was only a little worse compared to the past — now that we know the rate used to be much slower, we know that it’s much worse.

This chart shows as estimate of global sea level side from four different analyses, shown in red, blue, purple, and black. Shaded regions show uncertainty.

This chart shows as estimate of global sea level side from four different analyses, shown in red, blue, purple, and black. Shaded regions show uncertainty.

CREDIT: NATURE

“What this paper shows is that the sea-level acceleration over the past century has been greater than had been estimated by others,” lead writer Eric Morrow said in a statement. “It’s a larger problem than we initially thought.”

Specifically, previous research had stated the seas rose about two-thirds of an inch per decade between 1900 and 1990. But with the new study, that rate was recalculated to less than half an inch a decade. Both old and new research say that since 1990, the ocean has been rising at about 1.2 inches a decade, meaning the gap is much wider than previously thought.

Most scientists believe that the main driver of sea level rise is the thermal expansion of warming oceans and the melting of the world’s ice sheets and mountain glaciers, two phenomena driven by global warming. Antarctica, for example, is losing land ice at an accelerating rate. In December, scientists discovered that a West Antarctic ice sheet roughly the size of Texas is losing the amount of ice equivalent to Mount Everest every two years, representing a melt rate that has tripled over the last decade.

The common skeptic argument is that while Antarctica is losing land ice, it is actually gaining sea ice. While that’s true, sea ice melt does not affect sea level rise. It’s like an ice cube in a glass — if it melts, nothing happens. Up north in the Arctic, however, the loss of sea ice is just as important to look at, because when it melts, more sunlight is absorbed by the oceans. In Antarctica, sea ice melt is less of a problem for ocean warmth.

In addition, tropical glaciers in the Andes Mountains are melting, threatening freshwater supplies in South America. Some scientists have also predicted that the Greenland Ice Sheet — which covers about 80 percent of the massive country — is approaching a “tipping point” that could also have “huge implications” for global sea levels and ocean carbon dioxide absorption.

“We know the sea level is changing for a variety of reasons,” study co-author Carling Hay said. “There are ongoing effects due to the last ice age, heating and expansion of the ocean due to global warming, changes in ocean circulation, and present-day melting of land-ice, all of which result in unique patterns of sea-level change.”

All that may seem pretty grim, but there is a least one good thing to come out of the research — a new and hopefully more accurate method for measuring sea level rise. Before this study, scientists estimated global sea level by essentially dropping long yard sticks into different points of the ocean, and then averaging out the measurements to see if the ocean rose or fell.

For this study, Morrow and Hay attempted to use the data from how individual ice sheets contribute to global sea-level rise, and how ocean circulation is changing to inform their measurements. If the method proves to be better, it could serve to, as the New York Times put it, “increase scientists’ confidence that they understand precisely why the ocean is rising — and therefore shore up their ability to project future increases.”