Drivers of persistent changes in the global methane cycle under aggressive mitigation action

Abstract

To achieve the Paris climate agreement goals, methane (CH₄) emission mitigation plays a key role. Therefore, a better understanding of the global methane cycle is indispensable. Here we simulate the global methane cycle fully interactively from 1850 to 2100 with a strong mitigation action scenario (SSP1-2.6) post 2014. We show that the atmospheric methane burden largely recovers to early 20th-century levels, while wetland methane emissions follow a persistent upward trend from 166 Tg(CH₄) yr^–1 at pre-industrial to 221 Tg(CH₄) yr^–1 in 2100. The methane lifetime decreases from 9.3 to 7.3 years over the 1850–2100 period. We identify net primary productivity as the main driver behind the wetland methane trend with R² = 0.7. This implies that important components of the methane cycle (wetland methane, methane lifetime) are subject to Earth system feedbacks, potentially impacting any prospective methane mitigation action. Therefore, methane mitigation strategies will need to consider feedbacks in the Earth system.