High‐Altitude Lakes Have Become Emerging Carbon Sinks on the Qinghai‐Tibet Plateau

Abstract The lack of seasonal observations of CO 2 in lakes at altitude gradients over the Qinghai‐Tibet Plateau (QTP) limits the accurate assessment of CO 2 fluxes in lakes and the understanding of their variation mechanisms. We carried out seasonal observation of CO 2 fluxes in lakes at different elevation gradients over the QTP. We found that low‐altitude (<3,000 m) lakes can release a large amount of CO 2 (1.03 Tg C a −1 ), medium‐altitude (3,000–4,500 m) lakes can reduce CO 2 release (0.04 Tg C a −1 ), high‐altitude (>4,500 m) lakes were capable of absorbing large amounts of CO 2 (−0.65 Tg C a −1 ) from the atmosphere. The CO 2 fluxes of lakes on the QTP showed an inverse elevation effect. The multi‐source data analysis showed that the high‐altitude lakes of the QTP could also absorb a large amount of CO 2 (−0.25 Tg C a −1 ) from the atmosphere from 2000s to 2020s, which was equivalent to 4.5% of the CO 2 absorbed by the terrestrial vegetation of the QTP.