The unprecedented 2021 Western North America (WNA) heatwave, linked to a strong high-pressure system (heat dome), is analyzed. Using a flow analog method, the study finds the heat dome contributed to over half the anomalous temperature. Intensities of heat extremes associated with similar heat dome circulations increase faster than background global warming, partly explained by soil moisture-atmosphere feedback. Projections show increased probability of 2021-like extremes due to warming, enhanced feedback, and increased heat dome probability. Limiting warming to 1.5 °C instead of 2 °C (3 °C) would avoid 53% (89%) of increased population exposure under the RCP8.5-SSP5 scenario.

Xing Zhang, Tianjun Zhou, Wenxia Zhang, Liwen Ren, Jie Jiang, Shuai Hu, Meng Zuo, Lixia Zhang, Wenmin Man