Thermokarst lake drainage halves the temperature sensitivity of CH4 release on the Qinghai-Tibet Plateau

Abstract

Thermokarst lakes as hot spots of methane (CH4) release are crucial for predicting permafrost carbon feedback to global warming. These lakes are suffering from serious drainage events, however, the impacts of lake drainage on CH4 release remain unclear. Here, synthesizing field drilling, incubation experiments, and carbon composition and microbial communities, we reveal the temperature sensitivities (Q10) and drivers of CH4 release from drainage-affected lakes on the Qinghai-Tibet Plateau. We find that cumulative CH4 release decreases with depth, where 0–30 cm-depth sediment accounts for 97% of the whole release. The Q10 of surface sediment is 2 to 4 times higher than deep layers, but roughly 56% lower than the non-drainage lakes. The response of CH4 release to warming is mainly driven by microbial communities (49.3%) and substrate availability (30.3%). Our study implies that drainage mitigates CH4 release from thermokarst lakes and sheds light on crucial processes for understanding permafrost carbon projections.