Cleaner air in the United States and Europe prepares for more hurricanes in the Atlantica new US government study has revealed.
The National Oceanic and Atmospheric Administration study links changes in regionalized air pollution across the world to rising and falling storm activity. A 50% decrease in pollution particles and droplets in Europe and the United States is linked to a 33% increase in the formation of storms in the Atlantic over the past two decades, while the opposite is happening in the Pacific with more pollution and fewer typhoons, according to the study. published in Wednesday’s Science Advances.
NOAA hurricane scientist Hiroyuki Murakami performed numerous climate computer simulations to explain changes in storm activity in different parts of the globe that cannot be explained by natural climate cycles and found a link with aerosol pollution from industry and cars – sulfur particles and droplets in the air that make it difficult to breathe and see.
Scientists have long known that aerosol pollution cools the air, sometimes reducing the larger effects of greenhouse gases from burning fossil fuels. and earlier studies have mentioned it as a possibility of increased storms in the Atlantic, but Murakami found it to be a worldwide factor and a more direct link.
Hurricanes need hot water – which is heated by the air – for fuel and is damaged by wind shear, which alters upper-level winds that can decapitate the tops of storms. Cleaner air in the Atlantic and dirtier air in the Pacific, due to pollution in China and India, spoil both, Murakami said.
In the Atlantic, aerosol pollution peaked around 1980 and has been declining ever since. That means the cooling that masked some of the warming greenhouse gases is disappearing, so sea surface temperatures are rising even more, Murakami said. On top of that, the lack of cooling aerosols helped push the jet stream — the river of air that moves the weather from west to east on a roller coaster-like path — further north, reducing shear. which had dampened the formation of hurricanes.
“That’s why the Atlantic has gone pretty much crazy since the mid-90s and why it was so calm in the 70s and 80s,” said climatologist and hurricane expert Jim Kossin of risk firm The Climate Service. He wasn’t part of the study, but said it made sense. Aerosol pollution “gave a lot of people a break in the 70s and 80s, but we’re all paying for it now.”
There are other factors in tropical cyclone activity with La Nina and El Nino – the natural fluctuations in temperatures in the equatorial Pacific that alter the climate around the world – being enormous. Human-caused climate change from greenhouse gases, which will increase as reductions in aerosol pollution stabilize, is another, and there are other long-term natural climate oscillations. term, Murakami said.
Climate change due to greenhouse gases is expected to slightly reduce the total number of storms, but increase the number and strength of the most intense hurricanes, making them wetter and increase storm surge flooding, Murakami, Kossin and other scientists said.
While aerosol cooling is perhaps one-half to one-third smaller than greenhouse gas warming, it is about twice as effective at reducing the intensity of tropical cyclones compared to warming that increases it. , said Columbia University climatologist Adam Sobel, who was not part of the study. As aerosol pollution remains at low levels in the Atlantic and greenhouse gas emissions increase, the impact of climate change on storms will increase in the future and become more significant, Murakami said. .
In the Pacific, aerosol pollution from Asian countries increased by 50% between 1980 and 2010 and is starting to decline now. Tropical cyclone formation from 2001 to 2020 is 14% lower than from 1980 to 2000, Murakami said.
Murakami also found a slightly different correlation towards the south. A drop in aerosol pollution in Europe and the United States has changed global atmospheric patterns in a way that has led to fewer storms in the Southern Hemisphere around Australia.
But while more Atlantic hurricanes may be a problem, deaths from additional storms don’t compare to the seven million people a year worldwide who die from air pollution, Kristie said. Ebi, a professor of public health at the University of Washington, who studies health. , climate and extreme weather events.
“Air pollution is a major killer, so reducing emissions is essential no matter what happens with the number of cyclones,” said Ebi, who was not part of the study.
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