Pandemic and wildfires weakened Earth’s atmospheric oxidation in 2020
Science China PressPeer-Reviewed Publication
In a study published in National Science Review, researchers present multiple lines of observational and modeling evidence for a ~4% decline in global atmospheric oxidation capacity in 2020, reflected by a drop in hydroxyl radical (OH) concentrations. Using satellite-based carbon monoxide data, as well as methane and methyl chloroform observations, the study reveals that this OH reduction occurred in both hemispheres—approximately 2.4% in the Northern Hemisphere and 5.7% in the Southern Hemisphere—driven by distinct mechanisms. In the Northern Hemisphere, reduced NOx emissions due to COVID-19 lockdowns led to lower OH and tropospheric ozone levels, while in the Southern Hemisphere, massive emissions of reactive carbon from unprecedented Australian wildfires caused OH depletion but tropospheric ozone increases. This contrast in tropospheric ozone anomalies is further corroborated by satellite data. The findings help explain one of the record-breaking rises in atmospheric methane in 2020 and underscore the critical role of both natural and anthropogenic factors in shaping Earth’s atmospheric chemistry and global methane budget.
- Journal
- National Science Review
- Funder
- National Key Research and Development Program of China, National Natural Science Foundation of China, Westlake University