Methane emissions from thermokarst lakes must emphasize the ice-melting impact

<b>Thermokarst lakes, serving as significant sources of methane (CH</b>_{<strong>4</strong>}<b>), play a crucial role in affecting the feedback of permafrost carbon cycle to global warming. However, accurately assessing CH</b>_{<strong>4</strong>}<b> emissions from these lakes remains challenging due to limited observations during lake ice melting periods. In this study, by integrating field surveys with machine learning modeling, we offer a comprehensive assessment of present and future CH</b>_{<strong>4</strong>}<b> emissions from thermokarst lakes on the Tibetan Plateau. Our results reveal that the previously underestimated CH</b>_{<strong>4</strong>}<b> release from lake ice bubble and water storage during ice melting periods is 11.2 ± 1.6 Gg C of CH</b>_{<strong>4</strong>}<b>, accounting for 17 ± 4% of the annual total release from lakes. Despite thermokarst lakes cover only 0.2% of the permafrost area, they annually emit 65.5 ± 10.0 Gg C of CH</b>_{<strong>4</strong>}<b>, which offsets 6.4% of the net carbon sink in alpine grasslands on the plateau. Considering the loss of lake ice, the expansion of thermokarst lakes is projected to lead to a 1.1-1.2 folds increase in CH</b>_{<strong>4</strong>}<b> emissions by 2100. Our study allows foreseeing future CH</b>_{<strong>4</strong>}<b> emissions from the rapid expanding thermokarst lakes and sheds new lights on processes controlling the carbon-climate feedback in alpine permafrost ecosystems.</b>