Hurricanes weakened by air pollution? Study says trend towards cleaner air may bring stronger storms

Science has come up with some interesting ideas lately for helping us weaken hurricanes, in order to protect ourselves from having another storm like Katrina or Sandy, but for all the efforts to figure out this 'cloud brightening' idea, some meteorologists have figured out that we may inadvertently have been doing this already — through air pollution.

"Industrial emissions from America and Europe over the 20th Century have cooled the North Atlantic relative to other regions of the ocean," Dr. Nick Dunstone, the UK Met Office climate prediction scientist that lead the study said in a press release. "Our research suggests that this alters tropical atmosphere circulation — making it less likely that hurricanes will form."

"Since the introduction of the clean air-acts in the 1980s, concentrations of aerosols over the North Atlantic have reduced and model results suggest that this will have contributed to recent increases in hurricane numbers," he added. "On the other hand, the reduction in aerosols has been beneficial for human health and has been linked to the recovery of Sahel rains since the devastating drought in the 1980s."

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The way this works is that adding aerosols — tiny particles or droplets suspended in the air — cause the tops of clouds to become brighter than they would be otherwise, thus reflecting more sunlight back into space. This means that less sunlight gets to the ocean, which cools the ocean's surface, and since ocean temperatures are the primary driver for hurricane formation, this results in few hurricanes.

Using the results of sophisticated climate models, the researchers looked at how different climate factors influenced the Atlantic hurricane season between 1860 and 2050. According to records of the hurricane seasons since the beginning of the 20th century, there were fewer storms from 1900-1920 and 1970-1980, and there were more active periods from 1930-1960 and then from 1995 up until the present day.

When they used their climate models, and added in how much air pollution had been produced, they were able to show this same pattern of quiet and active periods.

"This supports evidence of a link between the two," said the press release.

"This study, together with work we published last year, suggests that there may be a greater role than previously thought for man-made influence on regional climate changes that have profound impacts on society," said Dr. Ben Booth, who co-authored the study, according to the Met Office release.

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The study also implies that, as we reduce the amount of industrial air pollution we release into the atmosphere, the number of Atlantic hurricanes will increase, and with studies already pointing to the fact that volcanic aerosols suppressed global warming for around 10 years, less aerosol pollution in the atmosphere may cause the full effects of global warming to show themselves in years to come. Hopefully, we can also reduce carbon dioxide emissions at the same time, so that we don't have to see that happen.

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