NCPA - National Center for Policy Analysis

Cleaner Air May Have Brought More Storms

August 2, 2013

The Clean Air Act, which has benefited breathing in many American cities over the last few decades, may have worsened the weather in some places. New climate simulations suggest that reducing the level of atmospheric aerosol particles produced by human activity might have been the main cause of a recent increase in tropical storm frequency in the North Atlantic, says Science News.

Aerosol levels have increased since the industrial revolution began, but there have been periods when emissions stalled or fell, such as the Great Depression, World War II, and after clean air legislation was enacted in Europe and the United States in the 1970s and 1980s.

  • The climate simulations suggest that these periods of low emissions eventually increased tropical storm frequency.
  • "It seems the Clean Air Act in particular has led to an increased number of hurricanes over the last decade or so," says Doug Smith of Met Office Hadley Centre in England, a coauthor of the research published June 23 in Nature Geoscience.

In the 20th century, aerosols probably had more effect on storm frequency than did greenhouse gases like carbon dioxide.

  • But greenhouse gases hang around for many decades, while aerosols stay in the atmosphere only for weeks.
  • The simulations suggest that by the end of the 21st century, greenhouse gases will reduce tropical storm frequency once more.

But in the near future, further improvements in air quality may lead to even more storms, Smith suggests. He cautions that atmospheric aerosols' effects on storms are not a good reason to let them increase again because they are hazardous to human health. Other researchers have suggested that decreased aerosols helped end the drought that devastated the Sahel region of Africa in the 1980s.

Source: Cristy Gelling, "Cleaner Air May Have Brought More Storms," Science News, July 27, 2013.


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