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PCIC Responds to June's Extreme Heat Wave

The recent extreme heatwave that gripped Western North America shattered many long-standing temperature records over a region that spans from southern Yukon to Oregon state, north to south, and from the Pacific coast to the Rocky Mountains, east to west. PCIC’s Climate Analysis and Monitoring Theme collaborated on a rapid attribution analysis of the event that garnered substantial global media attention. The Theme has also fielded media requests before, during and after the event, well into July.

The heatwave was caused by a very strong area of high pressure sometimes called a “heat dome.” Such high-pressure systems divert moist air from a region while simultaneously trapping heat near the surface, thus causing warm, dry conditions at the surface. High-pressure areas are a common occurrence in our region during the summer, bringing warm weather and clear skies, but the size and strength of this one was exceptional. In his interviews with the media, PCIC Climatologist Faron Anslow detailed the causes for this event and explained that this is the sort of event that can be expected more often as the climate changes. Excerpts from these interviews appeared in the Globe and Mail, CBC, Global News and in Victoria’s own Times Colonist.

The rapid attribution analysis began as the hottest day of the heat wave was still unfolding. The effort drew together long records of temperature data from weather stations, reanalysis data (in which weather observations are made into coherent representations of earth’s atmosphere using weather models) along with climate model output across a study region that included parts of Washington State, Southern BC and Northern Oregon. The authors found that the occurrence of the heatwave was “virtually impossible” without anthropogenic climate change. They estimated that such an event remains exceptionally unusual in our region in the current climate, with an estimated probability of occurrence of about 0.1% per year in the current climate. That probability is estimated to increase rapidly with additional warming, rising to 10-20% per year if the global mean temperature rises to a level that is 2°C above preindustrial levels, which could be reached as early as the 2040s with current rates of greenhouse gas emissions. The report, released by the World Weather Attribution initiative, has been covered widely by the international press, with well over 3400 articles published on it and numerous televised and radio interviews by many of the authors. In Canada, Faron has contributed to articles by the CBC, Times Colonist and the Globe and Mail among others.

Read excerpts from Faron’s interviews in articles by the Times Colonist, Vice and Global News.

Read about the rapid attribution analysis from the World Weather Attribution initiative, and coverage from CBC News, CBC News Canada Tonight, the Times Colonist and the Globe and Mail.
Read a Q&A interview on the report with Faron with UVic News.

Update, July 23rdWatch a special webinar for the Canadian Meteorological and Oceanographic Society on the rapid attribution analysis delivered by Faron.