Rapid analysis on the recent western North America heatwave event

Thursday, Jul 8, 2021
by The Department of Geosciences

Gabe Vecchi, Professor of Geosciences, Director of The High Meadows Environmental Institute, and Deputy Director of the Cooperative Institute for Modeling the Earth System, and Wenchang Yang, Geosciences Associate Research Scholar, have joined a team of international scientists to perform a rapid analysis on the recent western North America heatwave event. The key question they want to address is to what extent human-caused climate change has shifted the likelihood and intensity of such an extreme event. Their main findings include:

  • From both observations and climate models, the heatwave, measured as the annual maximum surface air temperature (TXx) averaged over the area of 45-52 ºN and 119-123 ºW, was virtually impossible without human-caused climate change.
     
  • In the most realistic statistical analysis the event is estimated to be about a 1 in 1000 year event in today’s climate. However, this likelihood still has already increased by 150 times from the pre-industrial climate. Furthermore, in the 2K warming world in which temperature is 2°C hotter than the pre-industrial era (0.8 degree celsius hotter than today), the event would occur more frequently, roughly every 5 to 10 years.
     
  • The intensity of the event has also increased by 2°C from pre-industrial era to the present and would further increase by another 1°C in the 2K warming world.

More information:
World Weather Attribution
worldweatherattribution.org/western-north-american-extreme-heat-virtually-impossible-without-human-caused-climate-change

Related article:
worldweatherattribution.org/wp-content/uploads/NW-US-extreme-heat-2021-scientific-report-WWA