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Millions of Americans are once again in the grip of dangerous heat. The warm weather that swept across Europe last weekend has caused parts of France and Spain to feel like it usually does in July or August. High temperatures burned northern and central china Even heavy rains caused flooding in the south of the country. Some places in India started to experience extraordinary heat The onset of monsoons in March brought some relief.
With only a few days to summer, it’s too soon to say whether climate change is directly to blame for causing severe heatwaves in these four strong economies, which are also the biggest emitters of heat-trapping gases.
As global warming makes extreme heat more common around the world, deeper analysis is needed to tell scientists whether certain weather events are more likely or more intense due to human-induced warming. (A group of researchers working the devastating heat of this spring He found that it increased the likelihood of climate change occurring in India by 30 times.)
Even so, for reasons related to the jet stream and other air rivers affecting weather systems around the world, simultaneous heatwaves seem to be hitting certain groups in the distance with increasing frequency lately.
Studies have shown This is how parts of North America, Europe, and Asia are connected. Scientists are trying to determine how these patterns might change as the planet gets warmer, but for now, it means that simultaneous extreme temperatures will continue to affect these places where the world’s economic activity is so intense.
“We need heat to have a heat wave, and we need atmospheric circulation patterns that allow heat to build up,” said climate scientist Daniel E. Horton of Northwestern University. With global warming, “we’re definitely getting more heat,” he said. But climate change may also be affecting the way that heat is dissipated around the world by air currents that surround it, he said.
Simultaneous extreme weather events in many places are not just meteorological curiosities. Individual heat waves can lead to: sickness and death, forest fires and crop failures. Concurrent ones can threaten global food suppliesunder dangerous tension This year due to the Russian invasion of Ukraine.
While heat waves are shaped by complexes local factors Like urbanization and land use, scientists no longer have much doubt about whether climate change is making them worse. The world’s most devastating heatwaves may soon have no historical analogues, shortly before humans began pumping greenhouse gases into the atmosphere. some scientists argueIt makes the question of whether climate change is the main driver obsolete.
Andrew Dessler, a climate scientist at Texas A&M University, said the warming of the past decades has already made it difficult for scientists to know what to call a heat wave and what will act as the new normal for warm weather.
For example, if the threshold for a heat wave is mercury exceeding 100 degrees Fahrenheit for days in a row, then Dr. It’s “not unexpected at all” to see these occur more regularly in several regions at the same time, Dessler said. “As time goes on, more and more parts of the planet will experience these temperatures, eventually with enough global warming every land area in the mid-latitude Northern Hemisphere will be over 100 degrees Celsius,” he said.
Yet even when scientists look at how often temperatures exceed a certain level relative to a moving average, they still find a large increase in the frequency of simultaneous heatwaves.
A last study The person who did this found that the average number of days between May and September when there was at least one major heat wave in the Northern Hemisphere doubled between the 1980s and 2010s, from 73 to 152. But the number of days with two or more heatwaves was seven times higher, rising from 20 to roughly 143. This is almost every day from May to September.
The study also found that these simultaneous heatwaves affected larger areas and were more intense in the 2010s, with peak temperatures almost a fifth higher than in the 1980s. The study found that days with at least one major heatwave somewhere in the Northern Hemisphere averaged 3.6 per day.
Deepti Singh, a climate scientist at Washington State University and author of the study, said these “dramatic” increases were a surprise.
Dr. Singh and his co-authors also looked at where simultaneous heat waves occurred most frequently during these four decades. One pattern stood out: Dr. Large simultaneous heatwaves hit eastern North America, Europe and parts of central and eastern Asia more and more frequently between 1979 and 2019 – “more than we expected due to warming alone,” Singh said.
The study didn’t try to predict whether heatwaves would become more frequent throughout this model as global warming continues, he said.
Scientists are working to pinpoint how the curves of the jet stream, which has long shaped weather patterns for billions of people, might change in this warming age. One factor is the rapid warming of the Arctic, which is narrowing the temperature difference between the northern and southern bands of the Northern Hemisphere. How exactly might this affect it? extreme weather still moot point.
But these temperature differences are key forces that drive the winds that move weather systems around the planet. These air currents could slow down as temperature differences narrow, he said. Kai KornhuberClimatologist at the Lamont-Doherty Earth Observatory at Columbia University, Dr. This includes extreme events such as heat waves and heavy downpour likely to take longer.
Dr. “The longer a heat wave lasts, the more you strain natural and social systems,” Kornhuber said.
Climate change will already see the world see more extreme weather events and more extremes happening simultaneously, he said. “These circulation changes are going to act on that,” he said, “making the extremes more severe and more frequent.”
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