CMIP6 Projections of the “Warming–Wetting” Trend in Northwest China and Related Extreme Events Based on Observational Constraints

This study presents the improved future projections of the climate “warming–wetting” trend and climate extremes with different return periods in Northwest China at different global warming levels. The projections are based on the Coupled Model Intercomparison Project phase 6 (CMIP6) simulations constrained by the high-resolution observation dataset using the equidistant cumulative distribution functions (EDCDF) method. The results indicate that the climate will experience continuous warming and wetting as reflected by average temperature and total precipitation over Northwest China, especially under the scenario of the shared socioeconomic pathway 5–representative concentration pathway 8.5 (SSP5-8.5). Most parts of Northwest China will continue to warm in the future more than global average. Spatially, areas with prominent “warming–wetting” trends will be mainly distributed in western Northwest China. It is worth noting that extreme heat and precipitation events will also increase with the climate warming and wetting over Northwest China. Moreover, frequencies of rarer extreme events will increase more apparently than weaker extreme events and frequency increase of extreme heat events responds to global warming faster than that of extreme precipitation events. Limiting global warming within 2°C relative to 1850–1900 would slowdown the increase in extreme heat events and considerably suppress the increase in frequencies of extreme precipitation events, especially the rare (i.e., 50-yr) extreme events.