Impact of reducing air pollution on the formation of tropical cyclones
A recent study by the US National Oceanic and Atmospheric Administration (NOAA), published in the journal Science Advances, revealed an unexpected effect of reducing air pollution in North America and Europe.
Effects of reducing air pollution.
The decline in air pollution over the past four decades has contributed to an increase in the number of tropical cyclones in the North Atlantic basin and a decrease in their number in the Southern Hemisphere. The study also found that increased pollution in Asia contributed to fewer tropical cyclones in the western and northern Pacific basin.
“Air pollution is a major environmental risk to human health, and we have made great progress in reducing health risks by reducing air pollution,” said Hiroyuki Murakami, a physical scientist at the Geophysical Fluid Dynamics Laboratory. of NOAA and author of the study. “But reducing air pollution does not always reduce the risk of tropical cyclones.”
Impact of pollution reduction on tropical storms in the Atlantic
Over the past 40 years, Europe and North America have been pioneers in reducing air pollution from particles emitted by industries, automobiles, power generation and other sources. The increasing absence of human-caused air pollution in the Northern Hemisphere, estimated to be a 50% decrease in concentration between 1980 and 2020, has contributed to sea surface warming over the tropical Atlantic Ocean, which in turn contributes to the formation of tropical zones. cyclones.
Without significant amounts of polluting particles reflecting sunlight, the ocean absorbs more heat and warms more quickly. Warming of the Atlantic Ocean was a key component in the 33% increase in the number of tropical cyclones during this 40-year period, Murakami said.
Impact of increased pollution in Asia on the formation of tropical cyclones
In the Pacific Northwest we see exactly the opposite of what is happening in the Atlantic basin. According to new research, air pollution is also a key component in reducing tropical cyclones in this region of the planet. In this case, a 40% increase in air pollution concentration was one of many factors contributing to the 14% reduction in tropical cyclones over the past 40 years, Murakami said.
Effects of increased air pollution.
Other factors include natural variability and increases in greenhouse gases. Over the Pacific Ocean, increased air pollution from the fast-growing economies of China and India has reduced the strength of the summer monsoons. Rising pollution “cools” the soil in East Asia, reducing the difference between land and ocean temperatures. Without this temperature contrast, the monsoons weaken. In general, tropical cyclones in Asia form in the summer in what is called the “Monsoon Valley,” where the western monsoons from India converge with the trade winds in the western Pacific. With weaker monsoons, there are fewer tropical cyclones.