According to a new US government study, cleaner air in the US and Europe is causing more Atlantic hurricanes.
Changes in regionalized air pollution across the globe are linked to increased and decreased storm activity, according to a study by the National Oceanic and Atmospheric Administration. According to a study published in Science Advances on Wednesday, a 50 percent decrease in pollution particles and droplets in Europe and the United States has been linked to a 33 percent increase in Atlantic storm formation in recent decades, while the Pacific has seen more pollution and fewer typhoons.
Hiroyuki Murakami, a NOAA hurricane scientist, ran numerous climate computer simulations to explain changes in storm activity in different parts of the world that can’t be explained by natural climate cycles, and discovered a link to aerosol pollution from industry and cars — sulfur particles and droplets in the air that make it difficult to breathe and see — and discovered a link to aerosol pollution from industry and cars.
Scientists have long known that aerosol pollution cools the air, limiting the bigger impacts of greenhouse gases produced by fossil fuel combustion, and previous research had linked it to an increase in Atlantic storms, but Murakami discovered it to be a global component with a more direct correlation.
Hurricanes require warm water for fuel, which is heated by the air, and are affected by wind shear, which is caused by variations in upper-level winds that can decapitate storm tops. Murakami believes that cleaner air in the Atlantic and dirtier air in the Pacific, resulting from pollution in China and India, wreak havoc on both.
Aerosol pollution in the Atlantic peaked in 1980 and has been steadily declining since then. As a result of the cooling that hid some of the greenhouse gas warming, sea surface temperatures are rising even faster, according to Murakami. Furthermore, the absence of cooling aerosols has aided in pushing the jet stream — the river of air that propels weather from west to east on a roller-coaster-like course — farther north, lowering the shear that has stifled storm formation.
“That’s why the Atlantic has gone pretty much crazy since the mid-90s and why it was so quiet in the 70s and 80s,” said climate and hurricane scientist Jim Kossin of the risk firm The Climate Service. He wasn’t involved in the research but agreed that it makes logical. “Aerosol pollution provided a lot of people a respite in the 1970s and 1980s, but we’re all paying for it today,” she says.
Other influences in tropical storm activity include La Nina and El Nino, which are natural oscillations in equatorial Pacific temperatures that affect global climate. Another is human-caused climate change from greenhouse gases, which will accelerate when aerosol pollution reductions plateau, as well as other natural long-term climatic cycles, according to Murakami.
According to Murakami, Kossin, and other scientists, climate change would reduce the total number of storms marginally while increasing the number and power of the most intense hurricanes, making them wetter and increasing storm surge flooding.
While aerosol cooling is only half to one-third as efficient as greenhouse gas warming in reducing tropical cyclone strength, it is roughly twice as effective in enhancing it, according to Columbia University climate scientist Adam Sobel, who wasn’t involved in the study. Climate change’s impact on storms will grow in the future as long as aerosol pollution remains low in the Atlantic and greenhouse gas emissions rise, according to Murakami.
Aerosol pollution from Asian countries in the Pacific increased by 50% between 1980 and 2010, and is now beginning to decline. Tropical cyclone generation is 14 percent lower from 2001 to 2020 than it was from 1980 to 2000, according to Murakami.
Murakami also discovered a slightly different association traveling south. A reduction in European and American aerosol pollution altered global air patterns, resulting in fewer storms in the southern hemisphere around Australia.