Earth spiked a bit of a fever in 2020, partly because of cleaner air from the pandemic lockdown, a new study reveals. Researchers found temperatures over parts of our planet’s land surface last spring were about 0.2 to 0.5 degrees Fahrenheit warmer than usual and it was due to a lack of air particles blocking incoming sunlight.
For a short time, temperatures in some places in the eastern United States, Russia, and China were as much as half to two-thirds of a degree warmer. The rise in temperatures is due to millions of people worldwide staying indoors during the peak of the coronavirus pandemic.
This resulted in less soot and sulfate particles from car exhaust and burning coal, which normally cool the atmosphere temporarily by reflecting the sun´s heat
Andrew Gettelman, an atmospheric scientist at the National Center for Atmospheric Research, said: ‘Cleaning up the air can actually warm the planet because that (soot and sulfate) pollution results in cooling which climate scientists have long known.’ The calculations come from comparing 2020 weather to computer models that simulated 2020 without the pollution reductions from pandemic lockdowns. Using these as markers, Gettelman and his team were able to identify the impact of reduced emissions on temperature changes that may have been overlooked.
This temporary warming effect from fewer particles was stronger in 2020 than the effect of reduced heat-trapping carbon dioxide emissions, Gettelman said. After the analysis, the team found that the warming effect was strongest in the mid and upper latitudes of the Northern Hemisphere.
The effect was mixed in the tropics and comparatively minor in much of the Southern Hemisphere, where aerosol emissions are not as pervasive. That´s because carbon stays in the atmosphere for more than a century with long-term effects, while aerosols remain in the air for about a week.
Even without the reduction in cooling aerosols, global temperatures in 2020 already were flirting with breaking yearly heat record because of the burning of coal, oil, and natural gas – and the aerosol effect may have been enough to help make this the hottest year in NASA´s measuring system, said top NASA climate scientist Gavin Schmidt, who wasn’t part of this study but said it confirms other research.
‘Clean air warms the planet a tiny bit, but it kills a lot fewer people with air pollution,’ Gettelman said.