Heatwaves Similar to the Unprecedented One in Summer 2021 Over Western North America Are Projected to Become More Frequent in a Warmer World

Western North America (WNA) experienced an unprecedented heatwave from late June to early July 2021, which lies far outside the historical range. Based on model outputs Coupled Model Intercomparison Project Phase 6, we find that likelihood of a over WNA similar 2021 one increases with global warming. Such is projected occur more frequently increased extreme temperature and shortened return period. It means rare event in current climate will be common warmer climate, especially under high-emission scenario like Shared Socioeconomic Pathways 585 (SSP5-8.5). Moreover, show large expansion areas break record future increasing level emission scenario. Nevertheless, some records west Rocky Mountains are still difficult break, highlighting specific extremity heatwave.