A study published in the journal Science explains the sharp increase in the concentration of methane in the atmosphere in the early 2020s.[4] The main cause was a temporary decrease in hydroxyl radicals (OH), which scavenge methane, during 2020–2021, caused by reductions in nitrogen oxides (NOₓ) and carbon monoxide (CO) emissions due to COVID-19 lockdowns.[2][3][4] This decrease in OH explains approximately 80% of the interannual changes in methane concentration growth.[1][2][3][4] The remainder was made up of increased methane emissions from wetlands, inland waters, agricultural crops and rice paddies, particularly in tropical Africa, Southeast Asia and the Arctic regions, supported by wet conditions during La Niña (2020–2023).[2][3][4] Methane concentration growth reached the highest observed values in 2020–2022, approximately 13 to 18 ppb per year.[5] The isotopic composition of methane (decrease in δ¹³C) confirms the dominance of microbial sources, not fossil fuels or fires.[4] After 2021, the Olympics recovered, which slowed methane growth.[3][4]