Here’s who lives in your city’s worst heat islands


Each point represents 700 inhabitants on average, and the color indicates the the hottest domains and cooler those.

You can swipe between cities at any time with the left and right arrows or with your keyboard.

We have grouped these areas into 10 groups, from hottest to coolest. Their temperatures are estimated from satellite photos taken between June and August from 2019 to 2021.

When we averaged the median income of each of the 10 groups, a pattern emerged: the higher the income of residents, the cooler their neighborhood, especially in metropolitan areas with populations of 300,000 or more.

We found something else too: the more immigrants, the warmer the region. Again, this is especially true for larger cities, where many newcomers live.

But why are some areas hotter than others? Lack of green space is a major factor, our analysis shows. The less vegetation there is, the hotter it is.

“We often say that tree maps are race and wealth maps,” said Carly Ziter, an associate professor of biology at Concordia University in Montreal who specializes in urban ecology, in reaction to CBC’s findings. The physical mechanism of cooling, such as what trees provide, is one of Ziter’s areas of expertise.

“This is proof that there is an inequity in who will be most vulnerable to climate change. Some people are lucky enough to live in cooler parts of cities that can mitigate these heat waves in the future. . And some don’t.”

— Carly Ziter, Associate Professor at Concordia University

She adds that low-income residents living in the hottest areas are also the population group with the fewest means to adapt, such as buying an air conditioner. According to Statistics Canada, in 2019, six out of 10 households owned a cooling unit. The lower a family’s income, the lower the probability of having AC.

According to our analysis, the proportion of low-income residents over the age of 65 is also highest in the hottest neighborhoods of many cities. This is the demographic group most vulnerable to heat waves.

How did we get our numbers?

Environment Canada’s weather stations are too rare to provide a detailed picture of air temperature in our cities. This is why we calculated the temperature of the earth’s surface of 17 metropolitan areas from satellite images. The total area covers 72,000 km2 with an accuracy of 30 meters. We used the 2016 census to determine the characteristics of residents. For more details, see the methodology at the bottom of this page.

In search of freshness

One solution seems fairly obvious: plant trees, which would provide shade while growing. “But these hot spots have another common characteristic: they’re dense,” said Jeffrey Brook, scientific director of the Canadian Urban Environmental Health Research Consortium. “Where are you going to plant a forest? There is no place.

Brook notes that density is also correlated with rental prices. In an urban context, a small apartment in a large building will be cheaper than a house with a garden. And low rents attract first-generation immigrants and low-income families. “We are really struggling to cope with the densification of our cities while having green spaces and affordable housing.”

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Even when there is space, planting trees or adding a park can have undesirable consequences. “You can create green gentrification,” explained Isabella Richmond, a PhD student at Concordia working on these issues under the supervision of Professor Ziter. As these areas become greener and more attractive, rents are likely to increase and current residents may be relocated.

“It would once again strengthen who lives in green areas,” Richmond said. “We need to put in place social and housing policies that go hand in hand with greening policies. For example, [a rule saying] you couldn’t immediately raise the rent after transforming a neighborhood.”

Between June 25 and July 1, 2021, a heat wave ravaged British Columbia and 619 people died from the temperature. An analysis conducted by the province determined that the deaths occurred primarily in low-income neighborhoods with little green space. Most of the victims were elderly people who died in their homes. They also had another characteristic: they were isolated.

“We can probably avoid heat-related deaths just by making sure we know where our vulnerable people live,” said Jeffrey Brook. “One of the reasons people die is because they don’t have anyone to take care of them, and I think the heat dome to the west proved that again.” We can reclaim parking spaces and green our roofs, but we also need to build social cohesion, argues Brook. “We need to think about community gardens, multi-generational housing and other projects that build social cohesion. That doesn’t take away from the fact that these areas definitely need improvement and we need to invest in these areas.”

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“We pay to improve our roads, bridges and buildings because we know we need them for our health and safety,” said Carly Ziter. “But increasingly we realize that we also need green infrastructure for our health and safety. So we shouldn’t think of it as an extra in our cities’ budget.”

And while cooling the outside air temperature will take a huge global effort, the Earth’s surface temperature can be reduced with local actions. “With a political decision, you can change the land surface temperature of an area,” said Philippe Martin, coordinator of an ultraviolet light program at Environment Canada and an expert in urban heat. To adapt to climate change, cities need more green and shaded spaces. He said they would be more bearable if streets were reconfigured to improve air circulation and new buildings could avoid using building materials that end up trapping heat.

Brook said Canadian governments at all levels must take the issue seriously. Canada has among the highest per capita greenhouse gas emissions in the world, he added. “What are we going to say 30 years from now? That we’re sorry and didn’t know better then? We know better. If you don’t treat your most disadvantaged people right, it’s not inherently sustainable. .”


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