Green or white roofs, trees and siesta against extreme heat | Toronto 2050

The frequency and duration of heat waves will continue to increase in Toronto over the coming decades, but the Queen City should be better prepared to deal with them. From roof colors to work hours, here are some of the changes experts are proposing.

If we know one thing about Toronto’s climate in 2050, it’s that it will be warmer and more humidsays Ewa Jackson, director of the Ontario Climate Adaptation Resource Center (CRACO).

According to the ClimaticData.ca portal, before the 2000s, Toronto generally experienced 12 days over 30°C per year. Today, the median is around 17 days.

Between 2051 and 2080, in a scenario where carbon emissions GES If planetary temperatures are weak, Toronto would record 35 days with a maximum temperature of more than 30° C per year.

In a moderate emissions scenario, which currently seems more likely, it would be 42 days.

Worst case scenario, it could be almost two months.

There is an expression that we often use: mitigation is avoiding what is unmanageable. Adaptation is about dealing with the inevitable. Part [des changements climatiques] are inevitableby Eve Jackson.

2050 isn’t that far away, but it’s far enough away to plant a few trees. […] At the very least we can paint our roofs white so they don’t absorb all this heat.

One of Toronto’s main challenges will be tackling its heat islands. And for this, experts are unanimous: trees will be a great ally.

40% of Toronto under the shade of trees

Trees provide shade, absorb carbon dioxide and provide oxygen and humiditylists Toronto’s director of urban forestry, Kim Statham.

Even a big tree in a heat island can lower the ambient temperature, she says.

Forest cover currently represents approximately 31% of Toronto, but we know that this is not distributed equitablysaid Kim Statham.

Industrial or commercial neighborhoods as well as those where many newcomers settle and where average incomes are lower are often well below the average.

For example, forest cover drops below 10% in part of Jane and Finch, in the north of the city, or in the northern part of Scarborough.

The City aims to achieve 40% forest cover by 2050 by prioritizing these neighborhoods.

No more dark roofs?

The city cannot be entirely devoted to trees and parks since Toronto is banking on densification to meet growing housing needs.

Buildings will therefore also have to be redesigned, according to experts.

In 2009, Toronto adopted a regulation on green roofs which requires certain categories of new buildings to grow vegetation on their roofs. The main purpose was to counteract flooding, but that is not their only advantage.

Usually, on a hot summer day, a decrease in temperature of one or two degrees is observed where there is a green roof. It’s a big impact, but it’s only really felt in the immediate surroundingssays Sean Thomas, professor and researcher at the John H. Daniels Faculty of Architecture at the University of Toronto.

Today, we have 2000 or 3000 green roofs […] and it represents a little more than a square kilometer in total area. But it remains a very small part of Toronto.

In sufficient numbers, these green roofs could help counter heat islands, but despite its efforts, Toronto is still far from the mark.

Right now, far less than 1% of roofs are like this. It would probably need to be 10 or 20% to start having a real impact.specifies the researcher.

Elsewhere on our airwaves:

For buildings that cannot support the weight of the substrate and plants, there are other solutions, points out Ewa Jackson.

Just painting the roofs white would help. […] It seems pretty obvious, but we don’t do it: when we look at our city, all the roofs are black or dark blue for some reason.

Clear roofs that reflect the sun’s rays instead of absorbing them are often called roofs. cool roofs. They require more maintenance than green roofs because they lose effectiveness if they are not kept clean, but they have the advantage of being simple and relatively inexpensive.

Protect the most vulnerable

Public policies will also have to adapt to Toronto’s new climate reality.

We should not have schools without air conditioning. We should not have homes for the elderly without air conditioning.says Ewa Jackson.

The City could also review the schedules of its employees who work outside so that they do not find themselves in the field between 11 a.m. and 3:30 p.m.

It seems crazy to think that we would siesta in North America, but if we find ourselves with 90 days where it is over 30 degrees, should we really work the same way as when we only had seven?

What concerns Ewa Jackson the most is the fate of homeless people as well as that of people who live alone and in housing without air conditioning.

Toronto Public Health estimates that heat already contributes to about 120 premature deaths per year.

The unprecedented heat dome that hit British Columbia in 2021 left 619 people dead. The majority of them were seniors who had chronic health problems and lived alone.

We need a better network of social connections, where people will check in on each other during a heatwave and combat loneliness while improving our climate resiliencesays Ewa Jackson.

Synagogues, churches, mosques, book clubs and neighborhood associations: all these places could become hubs for exchange and services during a heat wave, she believes.

Efforts already underway

The Toronto Green Standard requires builders of new housing projects to take steps to combat heat islands, such as reserving space for trees and using light-reflecting materials to pave surfaces.

In addition to the by-law on green roofs for new buildings, the City has a financial support program for owners who want to convert an existing roof into a green or cool roof.

This year, Toronto also adopted a new heat response strategy.

Ewa Jackson also believes that Toronto is on the right track to adapt to its new climatic reality.

Will it be enough? Will it be fast enough? It remains to be seenshe said.

At the same time, this expert emphasizes that if we can no longer avoid climate change, we can still limit their extent.

We must reduce our greenhouse gas emissions to ensure that what we are trying to adapt to does not exceed our capacity to adapt.she concludes.