Earth had a bit of a fever in 2020, in part due to cleaner air as a result of lockdowns implemented by the coronavirus pandemic around the world, according to a new study published Tuesday.
For a brief period, temperatures in parts of the eastern United States, Russia, and China were 0.3 to 0.7 degrees Celsius (one-half and two-thirds of a degree Fahrenheit) warmer. That’s due to fewer soot and sulfate particles from car exhausts and from burning coal, which normally cool the atmosphere temporarily by reflecting the sun’s heat, according to the study published in the journal. Geophysical Research Letters.
In total, the planet was 0.03 ° C (0.05 ° F) warmer in 2020 because the air had fewer aerosols, which unlike carbon dioxide, is a type of pollution that can be seen, he found the study.
“Cleaning the air can actually make the planet warmer because pollution (with soot and sulfates) causes cooling,” something climate scientists have known for a long time, said Andrew Gettelman, lead author of the study and an atmospheric scientist at the National Center for Atmospheric Research: Their calculations come from comparing the 2020 climate with computer models that simulated 2020 without the reduction in pollution caused by landfills.
This temporary warming effect from fewer particulate matter was stronger in 2020 than the effect of reduced carbon dioxide emissions, Gettelman said. That’s because carbon stays in the atmosphere for more than a century with long-term effects, while aerosols stay in the air for about a week.
Even without the reduction in aerosols, global temperatures in 2020 were already close to breaking the annual record for heat from the burning of coal, oil and natural gas, and the effect of the aerosols could have been enough to help that year it was the hottest in NASA’s measurement system, said NASA’s chief climate scientist Gavin Schmidt, who was not involved in the study but said it confirms other research.
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Follow Seth Borenstein on Twitter @borenbears
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