Projected changes to high temperature events for Canada based on a regional climate model ensemble

Here, I provide a short summary of a recent research that we undertook to assess climate change impacts on high temperature events over Canada. We evaluated projected changes to hot spells for the future 2040-2069 period with respect to the current 1970-1999 period, for the June to August period, based on a multi-RCM (regional climate model) ensemble available from the North American Regional Climate Change Assessment Program. Two types of hot spell events HS-1 and HS-2 were considered. HS-1 event has 3 or more consecutive days with Tmax above the 90th percentile, while an HS-2 event has 3 or more consecutive days with both Tmax and Tmin above the 90th percentile simultaneously. Heat wave events were defined as periods of three or more consecutive days of Tmax at or above the absolute Tmax threshold of 32 °C, following ECCC (Environment and Climate Change Canada). It must be noted though that this threshold may not be representative for northern regions of Canada. All RCMs suggest an increase in the number of hot spell days and events for the 2040-2069 future period. Results also suggest increases in the maximum duration of hot spells corresponding to longer return periods (e.g., 50-year) than that corresponding to shorter return periods (e.g., 10-year). Regionally, the RCMs project larger increases in hot spells over GRTLKS (Great Lakes), WCOAST (West Coast), MRTMS (Canadian Maritimes), and NPLAINS (Northern Plains) compared to other regions. The largest increase in heat wave days and events is noted for NPLAINS, followed by GRTLKS (Figure 1). Since these regions are very important for the economy of the country, more in depth studies are needed for these regions to facilitate appropriate adaptation measures for various sectors, including agriculture, livestock, fisheries, construction, transportation, utilities, environment, and human health.

Further details can be obtained from ( ).

Figure: Box and whisker plots of projected changes to HS-1 and HS-2 type hot spell days and heat wave days for the future 2040-2069 period with respect to the current 1970-1999 period, based on 11 RCM-AOGCM combinations.

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