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.