TTOP model simulation of long-term (1981–2100) permafrost dynamics of the Tibetan Plateau

• Mean annual ground temperature (MAGT) in Tibetan Plateau will increase by 1.5 – 4 °C from 2019 to 2100. • The future permafrost extent will be reduced to 17% of its original extent. • Permafrost in the headwater of Asian’s major rivers will face complete degradation. • Stable permafrost in the West Kunlun Mountains will become transitional and unstable. • A 1 km year-by-year MAGT product based on the TTOP model was provided. The Tibetan Plateau (TP) covers the largest regions under low- and mid-latitude permafrost. The evolution of permafrost has significantly affected the hydrology, biogeochemistry, and infrastructure of Asia. However, model reconstructions of long-term permafrost evolution with high accuracy and reliability are insufficient. Here, spatial changes in mean annual ground temperature at the depth where the annual amplitude is zero (MAGT) on the TP since 1981 were modeled and validated based on temperature records from 155 boreholes, and future changes were predicted under scenarios from the Climate Model Intercomparison Project 6 (CMIP6). The results indicated that the MAGT on the TP was approximately 1.5 °C (2010 – 2018), and the corresponding permafrost extent on the TP is estimated to be approximately 1.03 × 10 6 km 2 , which is projected to decrease to 0.77 × 10 6 , 0.50 × 10 6 , 0.30 × 10 6 , and 0.17 × 10 6 km 2 under the scenarios of shared socioeconomic pathway (SSP)126, SSP245, SSP370, and SSP585, respectively, by 2100. As predicted in the SSP585 scenario, permafrost is predicted to largely disappear from many basins of major Asian rivers, such as the Yarlung Zangpo-Brahmaputra, Nu-Salween, and Lancang-Mekong Rivers, between 2041 and 2060, followed by the Yellow and Yangtze Rivers between 2061 and 2080. Moreover, the original stable permafrost in the West Kunlun Mountains will change to transitional and unstable conditions. Our study offers comprehensive datasets of year-to-year ground temperatures and permafrost extent maps for the TP, which can serve as a fundamental resource for further investigations on the hydrogeology, engineering geology, ecology, and geochemistry of the TP.