Arquivo da tag: Ondas de calor

‘No One is Safe’: How The Heatwave Has Battered the Wealthy World (New York Times)

nytimes.com

Somini Sengupta


A firefighter battled the Sugar Fire in Doyle, Calif., this month.
C A firefighter battled the Sugar Fire in Doyle, Calif., this month. Credit: Noah Berger/Associated Press
Floods swept Germany, fires ravaged the American West and another heat wave loomed, driving home the reality that the world’s richest nations remain unprepared for the intensifying consequences of climate change.

July 17, 2021

Some of Europe’s richest countries lay in disarray this weekend, as raging rivers burst through their banks in Germany and Belgium, submerging towns, slamming parked cars against trees and leaving Europeans shellshocked at the intensity of the destruction.

Only days before in the Northwestern United States, a region famed for its cool, foggy weather, hundreds had died of heat. In Canada, wildfire had burned a village off the map. Moscow reeled from record temperatures. And this weekend the northern Rocky Mountains were bracing for yet another heat wave, as wildfires spread across 12 states in the American West.

The extreme weather disasters across Europe and North America have driven home two essential facts of science and history: The world as a whole is neither prepared to slow down climate change, nor live with it. The week’s events have now ravaged some of the world’s wealthiest nations, whose affluence has been enabled by more than a century of burning coal, oil and gas — activities that pumped the greenhouse gases into the atmosphere that are warming the world.

“I say this as a German: The idea that you could possibly die from weather is completely alien,” said Friederike Otto, a physicist at Oxford University who studies the links between extreme weather and climate change. “There’s not even a realization that adaptation is something we have to do right now. We have to save people’s lives.”

The floods in Europe have killed at least 165 people, most of them in Germany, Europe’s most powerful economy. Across Germany, Belgium, and the Netherlands, hundreds have been reported as missing, which suggests the death toll could rise. Questions are now being raised about whether the authorities adequately warned the public about risks.

Flood damage in Erftstadt, Germany, on Friday.
Credit: Sebastien Bozon/Agence France-Presse — Getty Images
A dry Hensley Lake in Madera, Calif., on Wednesday.
Credit: David Swanson/Reuters

The bigger question is whether the mounting disasters in the developed world will have a bearing on what the world’s most influential countries and companies will do to reduce their own emissions of planet-warming gases. They come a few months ahead of United Nations-led climate negotiations in Glasgow in November, effectively a moment of reckoning for whether the nations of the world will be able to agree on ways to rein in emissions enough to avert the worst effects of climate change.

Disasters magnified by global warming have left a long trail of death and loss across much of the developing world, after all, wiping out crops in Bangladesh, leveling villages in Honduras, and threatening the very existence of small island nations. Typhoon Haiyan devastated the Philippines in the run-up to climate talks in 2013, which prompted developing-country representatives to press for funding to deal with loss and damage they face over time for climate induced disasters that they weren’t responsible for. That was rejected by richer countries, including the United States and Europe.

“Extreme weather events in developing countries often cause great death and destruction — but these are seen as our responsibility, not something made worse by more than a hundred years of greenhouse gases emitted by industrialized countries,” said Ulka Kelkar, climate director at the India office of the World Resources Institute. These intensifying disasters now striking richer countries, she said, show that developing countries seeking the world’s help to fight climate change “have not been crying wolf.”

Indeed, even since the 2015 Paris Agreement was negotiated with the goal of averting the worst effects of climate change, global emissions have kept increasing. China is the world’s biggest emitter today. Emissions have been steadily declining in both the United States and Europe, but not at the pace required to limit global temperature rise.

A reminder of the shared costs came from Mohamed Nasheed, the former president of the Maldives, an island nation at acute risk from sea level rise.

“While not all are affected equally, this tragic event is a reminder that, in the climate emergency, no one is safe, whether they live on a small island nation like mine or a developed Western European state,” Mr. Nasheed said in a statement on behalf of a group of countries that call themselves the Climate Vulnerable Forum.

Municipal vehicles sprayed water in central Moscow on July 7 to fight midday heat.
Credit: Alexander Nemenov/Agence France-Presse — Getty Images
The Bootleg Fire in southern Oregon this week.
Credit: John Hendricks/Oregon Office of State Fire Marshal, via Associated Press

The ferocity of these disasters is as notable as their timing, coming ahead of the global talks in Glasgow to try to reach agreement on fighting climate change. The world has a poor track record on cooperation so far, and, this month, new diplomatic tensions emerged.

Among major economies, the European Commission last week introduced the most ambitious road map for change. It proposed laws to ban the sale of gas and diesel cars by 2035, require most industries to pay for the emissions they produce, and most significantly, impose a tax on imports from countries with less stringent climate policies.

But those proposals are widely expected to meet vigorous objections both from within Europe and from other countries whose businesses could be threatened by the proposed carbon border tax, potentially further complicating the prospects for global cooperation in Glasgow.

The events of this summer come after decades of neglect of science. Climate models have warned of the ruinous impact of rising temperatures. An exhaustive scientific assessment in 2018 warned that a failure to keep the average global temperature from rising past 1.5 degrees Celsius, compared to the start of the industrial age, could usher in catastrophic results, from the inundation of coastal cities to crop failures in various parts of the world.

The report offered world leaders a practical, albeit narrow path out of chaos. It required the world as a whole to halve emissions by 2030. Since then, however, global emissions have continued rising, so much so that global average temperature has increased by more than 1 degree Celsius (about 2 degrees Fahrenheit) since 1880, narrowing the path to keep the increase below the 1.5 degree Celsius threshold.

As the average temperature has risen, it has heightened the frequency and intensity of extreme weather events in general. In recent years, scientific advances have pinpointed the degree to which climate change is responsible for specific events.

For instance, Dr. Otto and a team of international researchers concluded that the extraordinary heat wave in the Northwestern United States in late June would almost certainly not have occurred without global warming.

A firefighting helicopter in Siberia in June.
Credit: Maksim Slutsky/Associated Press
Lytton, British Columbia, devastated by wildfires last month.
Credit: Darryl Dyck/The Canadian Press, via Associated Press

And even though it will take extensive scientific analysis to link climate change to last week’s cataclysmic floods in Europe, a warmer atmosphere holds more moisture and is already causing heavier rainfall in many storms around the world. There is little doubt that extreme weather events will continue to be more frequent and more intense as a consequence of global warming. A paper published Friday projected a significant increase in slow-moving but intense rainstorms across Europe by the end of this century because of climate change.

“We’ve got to adapt to the change we’ve already baked into the system and also avoid further change by reducing our emissions, by reducing our influence on the climate,” said Richard Betts, a climate scientist at the Met Office in Britain and a professor at the University of Exeter.

That message clearly hasn’t sunk in among policymakers, and perhaps the public as well, particularly in the developed world, which has maintained a sense of invulnerability.

The result is a lack of preparation, even in countries with resources. In the United States, flooding has killed more than 1,000 people since 2010 alone, according to federal data. In the Southwest, heat deaths have spiked in recent years.

Sometimes that is because governments have scrambled to respond to disasters they haven’t experienced before, like the heat wave in Western Canada last month, according to Jean Slick, head of the disaster and emergency management program at Royal Roads University in British Columbia. “You can have a plan, but you don’t know that it will work,” Ms. Slick said.

Other times, it’s because there aren’t political incentives to spend money on adaptation.

“By the time they build new flood infrastructure in their community, they’re probably not going to be in office anymore,” said Samantha Montano, a professor of emergency management at the Massachusetts Maritime Academy. “But they are going to have to justify millions, billions of dollars being spent.”

Christopher Flavelle contributed reporting.

Scientists Eye Longer-Term Forecasts of U.S. Heat Waves (Science Daily)

Oct. 27, 2013 — Scientists have fingerprinted a distinctive atmospheric wave pattern high above the Northern Hemisphere that can foreshadow the emergence of summertime heat waves in the United States more than two weeks in advance.

This map of air flow a few miles above ground level in the Northern Hemisphere shows the type of wavenumber-5 pattern associated with US drought. This pattern includes alternating troughs (blue contours) and ridges (red contours), with an “H” symbol (for high pressure) shown at the center of each of the five ridges. High pressure tends to cause sinking air and suppress precipitation, which can allow a heat wave to develop and intensify over land areas. (Credit: Image courtesy Haiyan Teng.)

The new research, led by scientists at the National Center for Atmospheric Research (NCAR), could potentially enable forecasts of the likelihood of U.S. heat waves 15-20 days out, giving society more time to prepare for these often-deadly events.

The research team discerned the pattern by analyzing a 12,000-year simulation of the atmosphere over the Northern Hemisphere. During those times when a distinctive “wavenumber-5” pattern emerged, a major summertime heat wave became more likely to subsequently build over the United States.

“It may be useful to monitor the atmosphere, looking for this pattern, if we find that it precedes heat waves in a predictable way,” says NCAR scientist Haiyan Teng, the lead author. “This gives us a potential source to predict heat waves beyond the typical range of weather forecasts.”

The wavenumber-5 pattern refers to a sequence of alternating high- and low-pressure systems (five of each) that form a ring circling the northern midlatitudes, several miles above the surface. This pattern can lend itself to slow-moving weather features, raising the odds for stagnant conditions often associated with prolonged heat spells.

The study is being published next week in Nature Geoscience. It was funded by the U.S. Department of Energy, NASA, and the National Science Foundation (NSF), which is NCAR’s sponsor. NASA scientists helped guide the project and are involved in broader research in this area.

Predicting a lethal event

Heat waves are among the most deadly weather phenomena on Earth. A 2006 heat wave across much of the United States and Canada was blamed for more than 600 deaths in California alone, and a prolonged heat wave in Europe in 2003 may have killed more than 50,000 people.

To see if heat waves can be triggered by certain large-scale atmospheric circulation patterns, the scientists looked at data from relatively modern records dating back to 1948. They focused on summertime events in the United States in which daily temperatures reached the top 2.5 percent of weather readings for that date across roughly 10 percent or more of the contiguous United States. However, since such extremes are rare by definition, the researchers could identify only 17 events that met such criteria — not enough to tease out a reliable signal amid the noise of other atmospheric behavior.

The group then turned to an idealized simulation of the atmosphere spanning 12,000 years. The simulation had been created a couple of years before with a version of the NCAR-based Community Earth System Model, which is funded by NSF and the Department of Energy.

By analyzing more than 5,900 U.S. heat waves simulated in the computer model, they determined that the heat waves tended to be preceded by a wavenumber-5 pattern. This pattern is not caused by particular oceanic conditions or heating of Earth’s surface, but instead arises from naturally varying conditions of the atmosphere. It was associated with an atmospheric phenomenon known as a Rossby wave train that encircles the Northern Hemisphere along the jet stream.

During the 20 days leading up to a heat wave in the model results, the five ridges and five troughs that make up a wavenumber-5 pattern tended to propagate very slowly westward around the globe, moving against the flow of the jet stream itself. Eventually, a high-pressure ridge moved from the North Atlantic into the United States, shutting down rainfall and setting the stage for a heat wave to emerge.

When wavenumber-5 patterns in the model were more amplified, U.S. heat waves became more likely to form 15 days later. In some cases, the probability of a heat wave was more than quadruple what would be expected by chance.

In follow-up work, the research team turned again to actual U.S. heat waves since 1948. They recognized that some historical heat wave events are indeed characterized by a large-scale circulation pattern that indicated a wavenumber-5 event.

Extending forecasts beyond 10 days

The research finding suggests that scientists are making progress on a key meteorological goal: forecasting the likelihood of extreme events more than 10 days in advance. At present, there is very limited skill in such long-term forecasts.

Previous research on extending weather forecasts has focused on conditions in the tropics. For example, scientists have found that El Niño and La Niña, the periodic warming and cooling of surface waters in the central and eastern tropical Pacific Ocean, are correlated with a higher probability of wet or dry conditions in different regions around the globe. In contrast, the wavenumber-5 pattern does not rely on conditions in the tropics. However, the study does not exclude the possibility that tropical rainfall could act to stimulate or strengthen the pattern.

Now that the new study has connected a planetary wave pattern to a particular type of extreme weather event, Teng and her colleagues will continue searching for other circulation patterns that may presage extreme weather events.

“There may be sources of predictability that we are not yet aware of,” she says. “This brings us hope that the likelihood of extreme weather events that are damaging to society can be predicted further in advance.”

The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under sponsorship by the National Science Foundation. Any opinions, findings and conclusions, or recommendations expressed in this release are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Journal Reference:

  1. Haiyan Teng, Grant Branstator, Hailan Wang, Gerald A. Meehl, Warren M. Washington. Probability of US heat waves affected by a subseasonal planetary wave patternNature Geoscience, 2013; DOI: 10.1038/ngeo1988