'Heat island' effect creating hotter conditions in Halifax, but there are solutions

Halifax's clogged arteries are doing more than steaming rush-hour commuters — they're also cranking up the temperature in the urban core, according to a researcher at Dalhousie University. 

Halifax is among a number of Canadian cities experiencing hotter weather than its outlying areas due to what's called the "heat island" effect, said Prof. Christine Macy.

The effect occurs when heat is absorbed by buildings with dark surfaces and asphalt or concrete roadways, effectively trapping heat and warming these surfaces.

Cities also tend to generate their own heat with the frequent use of vehicles and air conditioning units, exacerbating the effect. The severity depends largely on a city's layout and the amount of vegetation in its neighbourhoods. Macy, who teaches at Dalhousie's architecture school, said a dependency on vehicles is making the problem worse. 

She said Halifax has been prioritizing wider paved roads and new parking lots over trees and vegetation, intensifying the heat island effect. 

"They have been doing that since the 1950s, increasing the size of roads," she said. "When you replace greenscape with hardscape, it's absolutely making things worse."

The heat island effect can make a city up to five degrees warmer than surrounding areas, said Rob Leblanc, a landscape architect at Fathom Studio, an architecture firm in Dartmouth.

Although the effect is only getting worse as climate change intensifies, according to the Climate Atlas of Canada, there are ways to mitigate the heat the city is generating.

"I think some of the biggest impacts is reducing the amount of parking lots in urban areas or reducing the amount of streets," said Leblanc.

Leblanc said there are stronger measures that could be taken by the Halifax Regional Municipality and its residents. 

"Getting public transit to work better so that we don't need as many streets, getting active transportation, getting people on bikes," he said.

Shannon Fernandes, the manager of the city's climate adaptation division, said the city has been working on ways to curb the heat island effect since the spring. 

"We are seeing hotter summers and heat waves and more extreme heat temperatures and we are working on a number of initiatives to help address the heat island effect and extreme heat in our urban cores and across the municipality," said Fernandes. 

Some of these initiatives include keeping track of areas that are being hit particularly hard by the effect, the environmental factors involved and who is being most affected. This will also provide insight into what will decrease residents' vulnerability to heat, including increased vegetation and more cooling centres.