Future changes in daily snowfall events over China based on CMIP6 models

China has been frequently affected by severe snowstorms in recent years that have particularly large economic and human impacts. It is thus of great importance to increase our understanding of the underlying mechanisms of and future changes in snowfall occurrences over China. In this study, the effects of anthropogenic influences on snowfall and the associated future changes are explored using new simulations from CMIP6 (phase 6 of the Coupled Model Intercomparison Project) models. Observational evidence reveals a decrease in the annual total snowfall days and an increase in intense snowfall days over the snowfall-dominated regions in China during recent decades. Fingerprints of anthropogenic influences on these changes are detectable, especially the impacts of increased greenhouse gas emissions. During the winter seasons, low temperatures still cover the regions of northern China, and the associated precipitation days show an increase due to anthropogenic warming, which substantially benefits the occurrence of snowfall over these regions, particularly for intense snowfall events. This is also true in the future, despite rapid warming being projected. By the end of this century, approximately 23% of grids centered over northern China are projected to still experience an increase in daily intense snowfall events in winters. Additionally, the length of the snowfall season is projected to narrow by nearly 41 days compared to the current climate. Thus, in the future, regions of China, especially northern China, are likely to experience more intense snowfall days over a more concentrated period of time during the winter seasons.摘要近年来, 中国部分地区频繁遭遇极端降雪事件袭击, 造成巨大经济损失和人员伤亡. 因此, 亟需深入理解中国地区极端降雪变化的物理机制及其未来演变趋势, 为国家防灾减灾及气候变化应对措施制定提供科学依据. 本文基于CMIP6模式结果, 深入开展人类活动对中国地区降雪变化的影响及其未来演变趋势预估研究. 观测显示, 过去几十年在中国降雪频发区, 其年降雪日数呈现减少趋势但强降雪日数增加; 在这些变化中能够检测到人类活动的痕迹, 尤其是温室气体排放的影响. 对于冬季, 全球变暖背景下中国北方地区降水日数明显增加, 但北方地区仍为低温控制, 这有利于降雪尤其是强降雪事件的发生; 到了本世纪末, 中国仍有约23%的区域 (主要集中在北方地区) 其冬季强降雪日数呈现增加趋势. 此外, 中国地区降雪季长度相比当前气候减少了约41天. 因此, 在未来持续变暖背景下, 中国北方部分地区冬季将经历更多更为集中的强降雪事件.