A fixed methane filter maximizes freshwater emissions under warming (opens in new tab)

Approximately half of all methane (CH4) emissions come from freshwaters, where they are regulated by the microbial ‘CH4 filter’ whose efficiency describes the fraction of CH4 produced that is subsequently oxidized back to CO2 (methanotrophy) before emission. How the CH4 filter efficiency responds to natural warming over centuries or millennia remains unknown. Here we address this question using a natural experiment comprising high-latitude, geothermally warmed streams in five regions spanning...