Amplification of warming-wetting in high mountains and associated mechanisms during the 21st century in Xinjiang, Central Asia

As the arid center of Central Asia, Xinjiang in northwest China is characterized by a terrain of two basins surrounded by three mountains, with both climate and water resources highly sensitive to global warming. However, it remains unclear how climate in mountains and basins responds to global warming, leaving a gap to understand the water resource variability. Here, we project the climate change in Xinjiang in the 21st century from the perspective of topographic discrepancies using the ensemble mean of the five best models (BME) among 25 CMIP6 simulations. The results show that Xinjiang has experienced a warming-wetting trend since the 1961, which will continue in the future, but with a larger warming trend in basins and faster wetting rate in mountains. The wetting climate is predominantly attributed to the moisture increment by the enhancement of westerly circulation. In general, the wetting trend in mountains is 2.4 times higher than that in basins, while the warming rate in basins is 1.1 times that in mountains. This asymmetric warming-wetting pattern would induce the evaporation exceeding the precipitation in basins, leading to further drying of the basins. In contrast, the mountains are becoming wetter, indicating the high mountains in Xinjiang would have more water resources in a warming climate. Consequently, the water demand in basins would be more dependent on high mountains in a warming world, and it is urgent and imperative to protect the vulnerable mountains for water resource security in the arid regions.