Analysis of permafrost changes in the source region of the Yangtze and Yellow Rivers from 2001 to 2020 and prediction of future trends

ABSTRACT Climate change impacts have destabilized the permafrost in the SRYY. This study developed a MODIS land surface temperature correction equation for the SRYY, analyzed permafrost variations over 2001–2020 using the Stefan equation, the Temperature at the Top of Permafrost model (TTOP) model, and the soil thermal conductivity parameterization scheme, and applied a structural equation model to identify permafrost change drivers. Leveraging the CMIP6 data, future active layer thickness (ALT) and permafrost distribution were projected under diverse scenarios. The main conclusions are as follows: The ALT in the SRYY thickened at a rate of 1.06 cm/year, with significant changes concentrated in the Tuotuo and Damqu River basins. In the future about 2100, under SSP245, the ALT in the SRYY will increase by about 30 cm compared with the historical period, and the permafrost area will reduce by a minimum of 2 × 104 km2 and a maximum of 12.3 × 104 km2. And under the SSP585, the ALT will thicken by about 60 cm, with an average decrease in permafrost area of 16.3 × 104 km2. High-altitude permafrost exhibited stronger responses to climate change, faster warming rates mainly led to this result. Variations in moisture conditions were another important cause, in which soil water content was a key factor, and the role of precipitation deserved more consideration.