An international study reveals that the combination of the global health crisis and extreme climatic phenomena has “profoundly” altered the balance of the atmosphere, which since 2019 has been experiencing an unprecedented concentration of methane, the second greenhouse gas of human origin after CO2.
While scientists note that “the amount of methane, the second greenhouse gas of human origin after carbon dioxide, has increased at an unprecedented rate in the early 2020s,” the study “unveils today the mechanisms behind this surge,” according to a press release from the French National Centre for Scientific Research (CNRS), which participated in the work within the Laboratory of Climate and Environmental Sciences (LSCE).
In addition to the decline in emissions of certain pollutants observed during the lockdown, there is the “amplifying role of climate and wetlands,” according to the study recently published in the journal Science.
By analyzing satellite observations, ground measurements, atmospheric chemistry data, and using advanced computer models, the study highlighted two factors: “its reduced uptake in the atmosphere following the decrease in pollutant emissions” and “increased emissions from wetlands.”
According to CNRS, the study shows that a sharp decline in hydroxyl radicals between 2020 and 2021 explains about 80% of the annual variation in methane growth, noting that these radicals, whose decrease is partly linked to the lockdowns during the Covid-19 pandemic, are produced by ultraviolet radiation which transforms certain air pollutants into highly reactive molecules and play a key role in the “cleansing” of the atmosphere by destroying methane.
When their concentration fell, methane accumulated much more rapidly, the same source explains, noting that the reduction of emissions of certain atmospheric pollutants, such as nitrogen oxides and carbon monoxide, has “altered the chemistry of the air and temporarily weakened the atmosphere’s capacity to remove methane by reducing the concentration of these radicals.”
By providing “an integrated view of the interactions between climate, atmospheric chemistry and natural emissions,” this study offers “essential keys to better tracking the evolution of methane on a global scale,” and also reminds that “the fight against climate change hinges on a fine understanding of the natural, sometimes fragile, balances of our planet,” concludes CNRS.
