Atmospheric Methane Increase During Pandemic Due Primarily to Wetland Flooding
September 24, 2024 | Tracey Peake | 4-min. read

A new analysis of satellite data finds that the record surge in atmospheric methane emissions from 2020 to 2022 was driven by increased inundation and water storage in wetlands, combined with a slight decrease in atmospheric hydroxide (OH). The results have implications for efforts to decrease atmospheric methane and mitigate its impact on climate change.

“From 2010 to 2019, we saw regular increases – with slight accelerations – in atmospheric methane concentrations, but the increases that occurred from 2020 to 2022 and overlapped with the COVID-19 shutdown were significantly higher,” says Zhen Qu, assistant professor of marine, earth and atmospheric sciences at North Carolina State University and lead author of the research. “Global methane emissions increased from about 499 teragrams (Tg) to 550 Tg during the period from 2010 to 2019, followed by a surge to 570 – 590 Tg between 2020 and 2022.”

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They found that most of the 2020 to 2022 methane surge was a result of inundation events – or flooding events – in equatorial Asia and Africa, which accounted for 43% and 30% of the additional atmospheric methane, respectively. While OH levels did decrease during the period, this decrease only accounted for 28% of the surge.

“The heavy precipitation in these wetland and rice cultivation regions is likely associated with the La Niña conditions from 2020 to early 2023,” Qu says. “Microbes in wetlands produce methane as they metabolize and break down organic matter anaerobically, or without oxygen. More water storage in wetlands means more anaerobic microbial activity and more release of methane to the atmosphere.”

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