Friday, April 19, 2024

Pandemic lockdown’s clear skies have warmed the planet

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When countries began going into lockdown last winter and spring, clearer skies from reduced traffic and industry were hailed as a rare bright spot during a difficult time.

But a study published in Geophysical Research Letters in December 2020 shows that those blue skies had an unexpected side effect: They made the Earth slightly warmer.

“There was a big decline in emissions from the most polluting industries, and that had immediate, short-term effects on temperatures,” said Andrew Gettelman, lead author and National Center for Atmospheric Research (NCAR) scientist. “Pollution cools the planet, so it makes sense that pollution reductions would warm the planet.”

Soot and sulfate air pollution had the biggest impact, the study authors explained. Known as aerosols, these types of pollutants release particles into the atmosphere that either scatter sunlight on clear days or brighten clouds, reflecting sunlight. Both of these impacts mean less sunlight reaches Earth and temperatures cool.

In 2020, a reduction of these pollutants warmed global temperatures by about 0.1 to 0.3 degrees Celsius, the press release explained. The effect increased in places with higher aerosol emissions. Temperatures over China, Russia and the U.S. were as much as 0.37 degrees Celsius warmer, The Associated Press reported. All told, aerosol reduction may have contributed to 2020 experiencing one of the warmest years on record, NASA Climate Scientist Gavin Schmidt, who was not involved in the research, told The Associated Press. Read more…

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