The Future Climate Change Projections for the Hengduan Mountain Region Based on CMIP6 Models

In the context of global climate change, there is a lack of research quantifying the uncertainty of mountain ecosystems in relation to the CMIP6 multi-model ensemble simulations. This study aims to assess the future temperature and precipitation trends in the Hengduan Mountains under global climate change and quantify the uncertainty of CMIP6 multi-model ensemble simulations. Based on data from 11 CMIP6 climate models, the study uses bilinear interpolation to standardize model resolution, employs inverse distance weighting interpolation to analyze spatial distribution characteristics, and applies the multi-model ensemble mean method to reduce systematic biases. Through an equal-weight model selection method, EC-Earth3-Veg and MPI-ESM1-2-HR were identified as the optimal model combination. The research findings indicate: (1) During the reference period (1985–2014), the model simulations exhibit systematic biases, with simulated temperature values being 0.46 ± 0.08 °C/month lower and simulated precipitation values 2.07 ± 0.32 mm/month higher than the observations. (2) For the future period (2031–2070), the projected regional warming rates in typical years under the SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios are −0.294 ± 0.021°C/decade, 0.081 ± 0.009 °C/decade, and 0.171 ± 0.012 °C/decade, respectively. (3) Precipitation exhibits an overall decreasing trend, with the most pronounced decline under the SSP5-8.5 scenario (−0.68 ± 0.07%). This study is the first to systematically quantify the uncertainty of CMIP6 models in the Hengduan Mountains, revealing the regional climate change trends, provides scientific basis for developing adaptive strategies, and identifies key paths for improving regional climate models.