Research advance in changes and climate effect of methane

Methane is the second-largest greenhouse gas after carbon dioxide and has a significant impact on global climate. In order to assist China in better assessing future methane variations, thereby formulating methane emission reduction policies and ensuring the successful implementation of the "dual carbon" goals, this paper systematically reviews research progress on the patterns of atmospheric methane changes, their mechanisms, and climate effects over the past few decades. It is found that in recent decades, global methane levels have shown a significant increasing trend, primarily due to increased emissions from natural sources such as wetlands and frequent human activities like fossil fuel combustion and rice cultivation. Increasing methane in the troposphere can alter the radiative balance, leading to global warming. It can also affect tropospheric ozone indirectly by reacting with nitrogen oxides, thus influencing tropospheric radiative forcing. The increase in stratospheric methane affects global climate through chemical processes such as photochemical reactions. According to model predictions, global methane levels are expected to continue rising in the future, leading to an estimated global temperature increase. As countries implement methane emission reduction efforts, further research is needed to address how to achieve efficient methane reduction while balancing it with economic development.