The Tibetan Plateau acts as a net greenhouse gas sink.

The greenhouse gas budget on the Tibetan Plateau remains unknown and the potential for methane (CH4) and nitrous oxide (N2O) emissions from an intensifying livestock system and expanding surface water in offsetting terrestrial carbon dioxide (CO2) sinks are both of great concerns and uncertainties, which compromise an accurate assessment of Tibetan Plateau contribution to China's ambitious climate goals by 2060s. Here we integrated greenhouse gas flux measurements at ∼500 sites in empirical modeling approaches, emissions from the livestock sector with process-based biogeochemistry modeling to estimate CH4 and N2O fluxes across terrestrial ecosystems and inland waters in 2000s and 2010s. We found that emissions from livestock and inland waters, predominantly contributed by CH4, compensated ∼21% and ∼13% of carbon sinks provided by forests and grasslands after adjusting carbon burial in sediments and riverine carbon export, respectively. The Tibetan Plateau then acted as an appreciable greenhouse gas sink that almost compensated for its contemporary anthropogenic emissions, making it nearly climate-neutral. The enhancement of terrestrial CO2 sinks in the 2060s under medium warming scenario would be counterbalanced by livestock CH4 emissions when the current overgrazing status continues. By transitioning to a livestock-forage balance and implementing mitigation initiatives to reduce livestock emission intensity, the greenhouse gas sink is projected to increase by more than 1.5 times. We suggested that a transition towards sustainable pastoralism illuminates the path to minimizing ecosystem greenhouse gas emissions and amplifying the role of the Tibetan Plateau in fulfilling China's climate ambition.