Cleaner Air Is Causing More Hurricanes

You cannot open a newspaper or go to an online news source and not see at least one article about global warming citing greenhouse gasses as the main culprit in increased drought conditions, more severe storms, and warmer temperatures.

But ironically, scientists have discovered a link between cleaner air in the Atlantic and increasing storm activity. The good news is that reducing air pollution and aerosols from the atmosphere is working to improve air quality. The bad news is that this will impact the Eastern and Southern U.S. in an unanticipated deleterious way.

A recent study by the National Oceanic and Atmospheric Administration (NOAA) links changes in regional air pollution around the world to storm activity both increasing and decreasing. The conclusion: cleaner air in the United States and Europe is brewing more Atlantic hurricanes.

Europe and the United States have seen a 50% decrease in pollution particles and droplets over the past two decades. NOAA has linked this to a 33% increase in Atlantic storm formulation. By comparison, an increase in air pollution in the Pacific, coming from Asia, has resulted in fewer typhoons.

The study, published in Science Advances, looks at aerosol pollution from industry and cars (sulfur particles and droplets in the air that act as a sort of sunscreen for lowering air and water temperatures) and how it reduces the larger effects of greenhouse gasses. Scientists looked at climate computer simulations of storm activity changes around the world that could not be explained by natural climate cycles and found the link between pollution levels and storm activity.

Hurricanes (in the Atlantic) and typhoons (in the Pacific) need warm water for energy. Since less air pollution means more light from the sun can get through to heat the air and ocean, sea surface temperatures have risen in the Atlantic. The higher this temperature, the more likely a storm will develop and grow.

The lack of cooling aerosols/pollution has also helped push the jet stream that impacts storm development further north. This jet stream produces wind shear (a river of air that moves weather from west to east on a roller-coaster-like path) which usually decapitates storm tops and weakens them. With it no longer blanketing the part of the Atlantic where these storms usually develop from Tropical Storm status to Hurricane status, these hurricanes grow stronger as they reach land targets like the Caribbean, Gulf, and Atlantic coasts.

When Did This Trend Start

Aerosol pollution peaked around 1980 in the Atlantic and has been dropping ever since. "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," according to climate and hurricane scientist Jim Kossin.

By comparison, aerosol pollution from Asia increased 50% from 1980 to 2010, though it is starting to drop this decade. Cyclone formation in the Pacific is 14% lower from 2001 to 2020 than it was from 1980 to 2000.

What Does This Mean for the U.S. and The Rest of the World?

Scientists have long predicted that climate change from greenhouse gases would reduce the overall number of storms, but increase the number and strength of the most intense hurricanes. These storms will be wetter with greater storm surges and wind speeds. The aerosol cooling that comes from air pollution is considerably smaller than greenhouse gas warming, yet twice as effective in reducing tropical cyclone intensity. Low aerosol pollution in the Atlantic with growing greenhouse gas emissions will result in more storms than originally anticipated.

While not great news for the U.S., Caribbean nations, and Central America, the news may be good for for Australia. The drop in European and American aerosol pollution has altered global air patterns in the southern hemisphere around Australia and weakened storms there.

While the risk to the U.S. from more frequent and severe Hurricanes is very unfortunate and problematic, the loss of human life in these storms is very small when compared to the seven million people who die each year from air pollution.

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Sources: NOAA, Scientific American