Impact of interannual and multidecadal trends on methane-climate feedbacks and sensitivity

This research estimates the causal contributions of temperature and precipitation changes to atmospheric methane concentration and its isotope ratio over the past four decades. It reveals oscillations between positive and negative methane-climate feedbacks, with both contributing to increasing methane levels. Interannual variations show increased emissions via positive feedbacks (wetlands, wildfires) followed by increasing methane due to weakened sinks. Decadal trends reveal alternating rate-limiting factors for methane oxidation, with positive feedback dominating when methane is limiting and negative feedback when ·OH is limiting. Incorporating negative feedbacks yields a higher methane-climate feedback sensitivity than the IPCC AR6 estimate.

Chin-Hsien Cheng, Simon A. T. Redfern