EGU23-10709
https://doi.org/10.5194/egusphere-egu23-10709
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

The Unprecedented Pacific Northwest Heatwave of June 2021: Causes and Impacts

Rachel White1, Sam Anderson2, James F. Booth3, Ginni Braich4, Christina Draeger2, Cuiyi Fei2, Christopher D. G. Harley5, Sarah B. Henderson6,7, Matthias Jakob2,8, Carie-Ann Lau8, Lualawi Mareshet Admasu2, Veeshan Narinesingh9,10, Christopher Rodell2, Eliott Roocroft2, Kate R. Weinberger7, and Greg West2,11
Rachel White et al.
  • 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada (rwhite@eoas.ubc.ca)
  • 2Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
  • 3City College of New York; City University of New York - The Graduate Center, New York, USA
  • 4Institute for Resources, Environment and Sustainability, University of British Columbia, Vancouver, Canada
  • 5Department of Zoology, University of British Columbia, Vancouver, Canada
  • 6British Columbia Centre for Disease Control (BCCDC), Vancouver, Canada
  • 7School of Population and Public Health, University of British Columbia, Vancouver, Canada
  • 8BGC Engineering Inc, Vancouver, Canada
  • 9NOAA Geophysical Fluid Dynamics Laboratory, Princeton, USA
  • 10Department of Natural Sciences and Mathematics, Sarah Lawrence College, Bronxville, USA
  • 11BC Hydro, Vancouver, Canada

In late June 2021 a heatwave of unprecedented magnitude impacted the Pacific Northwest (PNW) region of Canada and the United States. Many locations broke all-time maximum temperature records by more than 5°C, and the Canadian national temperature record was broken by 4.6°C, with the highest recorded temperature 49.6°C. Local records were broken by large margins, even when compared to local records broken during the infamous heatwaves in Europe 2003, and Russian in 2010. A region of high pressure that became stationary over the region (an atmospheric block) was the dominant cause of this heatwave; however, trajectory analysis finds that upstream diabatic heating played a key role in the magnitude of the temperature anomalies. Weather forecasts provided advanced notice of the event, while sub-seasonal forecasts showed an increased likelihood of a heat extreme with 10-20 day lead times, with an increased likelihood of a blocking event seen in forecasts initialized 3 weeks prior to the heatwave peak. The impacts of this event were catastrophic. We provide a summary of some of these impacts, including estimates of hundreds of attributable deaths across the PNW, mass-mortalities of marine life, reduced crop and fruit yields, river flooding from rapid snow and glacier melt, and a substantial increase in wildfires—the latter contributing to devastating landslides in the months following. These impacts provide examples we can learn from, and a vivid depiction of how climate change can be so devastating.

How to cite: White, R., Anderson, S., Booth, J. F., Braich, G., Draeger, C., Fei, C., Harley, C. D. G., Henderson, S. B., Jakob, M., Lau, C.-A., Mareshet Admasu, L., Narinesingh, V., Rodell, C., Roocroft, E., Weinberger, K. R., and West, G.: The Unprecedented Pacific Northwest Heatwave of June 2021: Causes and Impacts, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-10709, https://doi.org/10.5194/egusphere-egu23-10709, 2023.

Supplementary materials

Supplementary material file