Greenhouse gas: Clean air during Corona pandemic caused methane levels to rise
As global economy hit a standstill in the fight against COVID-19, the air measurably became cleaner. This had unexpected effects on a powerful greenhouse gas.
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The shutdown of the global economy during the Corona pandemic played a decisive role in the fact that the methane concentration in the atmosphere rose unexpectedly sharply from 2020 onwards. This is a central finding of a study for which, among other things, Earth observation data from ESA were evaluated. It revealed that in the course of the reaction to the pandemic, fewer nitrogen oxides and carbon monoxide were emitted, among other things, which is why fewer so-called hydroxyl radicals entered the atmosphere. Precisely these, however, are responsible for the breakdown of methane there, which is why it was hindered. The reduction in air pollution has thus led to unexpected consequences, which could become important in the fight against climate change.
Less air pollution = more methane
According to ESA, the temporarily sharp increase in methane concentration in the atmosphere came as a surprise to researchers. When economies in most countries around the world were shut down and people were told to stay home, emissions of most pollutants decreased. This was contrasted by methane emissions, which rose sharply in 2020 and only decreased again years later. It was not until 2023 that the levels customary before the Corona pandemic were reached again. According to ESA, the growth rate of methane concentration had temporarily doubled to 16.2 parts per billion per year. According to the study, only a small part of this increase was due to temporarily increased methane emissions from wetlands as a result of the climate phenomenon La Nina.
More than 80 percent of the temporary increase can be explained, according to the study, by the fact that fewer hydroxyl radicals entered the atmosphere, ESA now writes. These are formed by chemical reactions under the influence of sunlight, ozone, water vapor, and gases originating from combustion processes. According to New Scientist, the connection had already been established earlier in an analysis, but at that time it could not be explained why the increase continued in 2021 and 2022. It is now clear that emissions from air and shipping were responsible for this persistence. Both economic sectors took longer to return to pre-pandemic levels.
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Methane is significantly more effective as a greenhouse gas than carbon dioxide and contributes significantly to global warming. At the same time, however, it does not remain in the atmosphere for as long, so the effects are much shorter-term than those of COâ‚‚. Nevertheless, rising emissions could prove to be the biggest obstacle on the path to limiting global warming to under 1.5 degrees Celsius. Therefore, reducing methane emissions is considered particularly desirable. The study, now published in the journal Science, suggests that a reduction in air pollution could lead to more methane remaining in the atmosphere. This shows once again how complex the Earth's atmosphere is and what unexpected obstacles the fight against climate change may still hold.
(mho)
