Exploring the Evolution of Permafrost on the Tibetan Plateau (1979–2100) Using the Temperature at the Top of Permafrost (TTOP) Model: Implications for Sustainable Development

The permafrost in the Tibetan Plateau is extremely sensitive to climate warming, which poses challenges to regional sustainability. Predicting the evolution of permafrost on the Tibetan Plateau in the future could provide a reference for future engineering, construction, and resource management on the Tibetan Plateau. In this study, the Random Forest regression model and the temperature at the top of permafrost (TTOP) model are combined. The Random Forest regression model is used to simulate the long-term series of land surface temperatures. The multiple climate model data sets in the Coupled Model Intercomparison Project Phase 6 (CMIP6) and TTOP model are used to simulate the historical (1979–2018) and predict the future (2019–2100) distribution of permafrost on the Tibetan Plateau. The results show that since 1979, due to climate warming, more than 20% of the permafrost in the Tibetan Plateau has disappeared. The permafrost will degrade at different rates under each of four Shared Socioeconomic Pathways (SSPs), namely SSP1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5. The degradation rate under SSP1–2.6 is the slowest, indicating that about 20.1% of the permafrost will disappear by 2100. The degradation rate under the SSP5–8.5 is the fastest, predicting that about 82.4% of the permafrost will disappear by 2100. Under SSP2–4.5 and SSP3–7.0, 37.57% and 69.1% of the permafrost will disappear by 2100, respectively. The above results can provide a reference for sustainable engineering construction, infrastructure planning, and climate adaptation strategies on the Tibetan Plateau.