Warming holes: When air pollution masks rising temperatures

In the 1980s, while the rest of the United States was experiencing steadily rising temperatures, the southeast appeared to actually be cooling down. This cooling effect had previously baffled scientists, until efforts to clean the atmosphere of air pollution resulted in an increase in southeastern temperatures, aligning with other regions affected by climate change. These warming holes are caused by heavy pockets of airborne pollutants and aerosols that successfully mask rising temperatures.

Heavy concentrations of pollutants essentially stop sunlight from reaching the ground and increase cloud coverage, which reflect sun rays away from the Earth. But when the EPA enacted regulations to reduce aerosols pollution, heavily polluted and smoggy areas in the Southeast saw resumed rising temperatures.

The research was conducted by a team of scientists from NASA’s Jet Propulsion Laboratory and the California Institute of Technology, with lead author Dr. Mike Tosca. The researchers used satellite data that measured aerosol pollutants and also looked at surface temperature weather maps.

The researchers found that when aerosol pollution decreased by about 20 percent from 2000 – 2015, a temperature spike of almost 1 degree Celsius was recorded. These findings show strong evidence that pollutants mask the effects of climate change and can cause warming holes in certain areas of the world where high concentrations of airborne aerosols are present.

Because temperatures increased so quickly in the Southeast with improved air quality, this could mean that areas with high concentrations of airborne pollutants like India and China could be faced with even higher temperatures if they reduce aerosol emissions.

Quickly rising temperatures due to warming holes could foreshadow disastrous consequences, with parts of Asia already predicted to be unlivable due to extreme heat by the year 2100.

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By Kay Vandette, Earth.com Staff Writer