Study: Australian fires had bigger impact on climate than lockdowns in 2020

The 2019 to 2020 Australian wildfire season was historic. More than 42 million acres burned in an unprecedented outbreak of extreme fires, which produced lightning, launched smoky aerosols into the stratosphere and turned New Zealand’s glaciers brown with ash. The suffocating smoke was blamed for hundreds of deaths.

Now a new study published in Geophysical Research Letters suggests that the fires’ impact may have spread around the globe. Researchers with the National

Center for Atmospheric Research (NCAR) in Boulder, Colo., found that smoke produced by the fires cooled the global climate and had a greater impact than the change in emissions stemming from covid-19 lockdowns, which had a small warming influence.

“Beyond their effect on local weather, wildfires are becoming large enough, and intense enough, to have a material effect on climate,” said John Fasullo, the lead author of the study. “In this work, we demonstrate their potential to influence climate variability. We are still in the process of understanding other aspects.”

Fasullo and his colleagues concluded that the 2019-2020 Australian wildfire season resulted in 0.1 degrees Fahrenheit of cooling by mid2020. The cooling, however, was tacked atop a continued net warming of the climate and had a negligible effect on slowing the pace of humaninduced climate change from fossil fuel burning.

The team’s assessment stemmed from the outputs of a computer model ensemble, which simulated global temperatures in the 2015 to 2024 time frame under the same background conditions but with and without emissions from the biomass burned in Australia’s wildfires.