Clean air may increase tropical storm activity

Science News : Global aerosol levels have been increasing since the 1800s, but they have also seen periods of stall or decline—during the Great Depression and World War II and following the passing of clean air acts in Europe and the US in the 1970s and 1980s. According to new climate simulations run by Doug Smith of Met Office Hadley Centre in England and his colleagues, the periods of decline seem to stimulate tropical storm activity. The simulations suggest that increases in aerosols over the North Atlantic cool the surface of the ocean and suppress tropical storm formation. When the local production of aerosols decreases, the frequency of storm formation increases. The simulations go on to predict that further air quality improvements may increase storm formation in the short term, but the continuing increase in greenhouse gases will reduce tropical storm activity by the end of the 21st century.