At the height of the coronavirus pandemic, the Earth saw a surge in emissions of heat-trapping methane. While some research shows the spike was related to the global drop in traffic during the pandemic, a new study suggests the sudden rise in methane levels was mostly due to flooding in the tropics.
Generally, pollution from cars, trucks, and planes reacts with water to form the hydroxyl radical, a short-lived gas that scrubs methane from the atmosphere. Some research shows that when pandemic lockdowns grounded planes and thinned car traffic, pollution dropped and methane levels rose. But stalled transport could only partially explain the sudden uptick in methane.
The new modeling study finds that flooding in the tropics accounts for most of the methane spike from 2020 to 2022. With the Pacific in its cooler La Niña phase, equatorial Asia and Africa saw heavy rainfall and flooding.
In inundated wetlands and rice paddies, microbes broke down plants, producing huge sums of methane as a byproduct. The study, published in the Proceedings of the National Academy of Sciences, finds that flooding in Asia and Africa accounted for 73 percent of the methane surge.
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