Global Warming Will Increase the Risk of Water Shortage in Northwest China

Abstract

Abstract Drylands with fragile ecosystems and severe water shortages are particularly vulnerable to climatic change. Northwestern China (NWC), a typical arid region, faces uncertainty regarding future wetting or drying trends. A comprehensive assessment and projection of these conditions are crucial for water resource management. In this study, we employ a Lagrangian trajectory model, optimal fingerprint analysis, and a maximum covariance technique to evaluate wetting and/or drying trends in NWC over the historical (1981–2023) and future (2024–2099) periods. Our results show that over 80% of NWC experienced increases in air temperature, precipitation, and evaporation during the historical period. External and internal water vapor sources contribute 92% and 8%, respectively, to precipitation changes. Incoming water vapor predominantly originated from the North Atlantic (31.9%) and the South China Sea ‐ Bay of Bengal region (39.3%), with a strong positive correlation ( r = 0.71) between Atlantic sea surface temperatures and precipitation minus evaporation in NWC. Water vapor enters NWC from the southern, northern, and western boundaries, while 83.4% escapes through the eastern boundary. The precipitation trend is strongly influenced by the combined effects of anthropogenic and natural forcings, accounting for 36.8% to the observed increase. Under a 1.5°C warming scenario, warming‐wetting regions shift northward, whereas higher warming levels (2°C, 3°C, 4°C) cause these regions to shift southeastward and shrink. Our findings underscore NWC's high sensitivity to climate warming and highlight the pressing challenge of water security in a warming world.