The Impact of the Urban Heat Island Effect on Edmonton

The Impact of the Urban Heat Island Effect on Edmonton
The Impact of the Urban Heat Island Effect on Edmonton

While all Edmontonians are currently suffering from the heat wave, some are likely feeling it more than others, a University of Alberta researcher says.

Cities are often warmer than rural areas due to the urban heat island effect: dense and paved infrastructure amplifies and retains heat.

But the same things that cool rural areas – primarily trees and other vegetation that provide shade, as well as bodies of water – can also have a cooling effect in urban areas, or lead to fluctuating temperatures in a city when integrated into infrastructure design.

In Edmonton, where the urban heat island effect keeps some parts of Alberta’s capital city 12 degrees warmer than surrounding rural areas, both neighbourhood design and the orientation of the North Saskatchewan River have an impact, Sandeep Agrawala, a professor of urban and regional planning, told CTV News Edmonton on Tuesday.

“The south benefits from a vast canyon system and tributaries and creeks with vegetation along them, so that helps tremendously,” Agrawala said

“But we do see the heat island effect in some of the newer neighbourhoods in south Edmonton where vegetation has been cleared, trees have been removed and the neighbourhoods have largely been paved over.”

Concrete and asphalt are called low-albedo surfaces, meaning they absorb more heat than they reflect.

“Essentially, they continue to absorb heat and then slowly release that heat into the environment. That then increases the ambient temperature above what it normally is,” Agrawala explains.

During a heat wave like the current one, he added, “the higher the temperature, the more heat is absorbed by these surfaces, ultimately releasing more heat to the environment.”

Research conducted in the US also suggests Communities of color and lower-income communities are disproportionately affected by urban heat islands, in part due to the U.S. government’s historic redlining practices.

Urban heat islands pose a “very serious problem” as global temperatures rise and more people die or are affected by heat exposure, Agrawala said.

“The best way to limit the impact is to protect trees,” he told CTV News Edmonton.

Protecting trees can be done, for example, through municipal ordinances that regulate trees on public and private land. For example, citizens and developers would not be allowed to remove vegetation and would have to limit the amount of low-albedo materials they use in their designs.

With files from Connor Hogg of CTV News Edmoton