Urban Heat

Extreme heat events are anticipated to become longer, more frequent, and more intense because of climate change. On average, Canada is warming at twice the global rate. By the mid-21^st century, many parts of the country are projected to have double the number of very hot days each year.[1] For Canadians living in urban areas, there is an even great consequence.

Urban heat island (UHI) effect refers to warmer temperatures in urban areas compared to surrounding rural areas. UHIs occur in highly developed areas where humans have altered the surface of the land through the construction of buildings, roads and other infrastructure. In urban areas, surface daytime temperatures can be 10-15° hotter than in surrounding rural areas, and nighttime temperatures up to 12° hotter.[2]

Canadian cities face the greatest risk from extreme heat because of the UHI effect. Almost three in four Canadians live in cities: in 2021, 73.7 percent of Canadians lived in large urban centres. Furthermore, from 2016 to 2021, these cities accounted for most of Canada’s population growth (+5.2 percent).[3]

One tool to better understand how increasing temperatures will impact communities is to develop UHI maps. However, mapping methods are diverse, making comparability between maps challenging. That’s why we are supporting further work in this area.

[1] Reducing urban heat islands to protect health in Canadians 

[2] Ibid

[3] Ibid