Climate feedback from wetland emissions of methane may necessitate
larger anthropogenic reductions to stay within 1.5°C or 2.0°C warming
Abstract
In 2020, global atmospheric methane (CH4) levels increased by 14.7
parts-per-billion (ppb) - the largest annual increase since atmospheric
records began in 1983
(https://research.noaa.gov/article/ArtMID/587/ArticleID/2742/Despite-pandemic-shutdowns-carbon-dioxide-and-methane-surged-in-2020)
continuing an upward trend since 2007. This is concerning since CH4 is
the second most important long-lived greenhouse after CO2 and has global
warming potential 28 times that of CO2 per unit mass on a 100-year time
scale (Myhre et al. 2013). Moreover, pathways to limit global warming to
1.5°C, or even 2.0°C, require non-CO2 emissions and, in particular, CH4
emissions, to be reduced by 35% with respect to 2010 levels by 2050
(Forster et al. 2018).