Hot Cities, Cool Parks

After three years without air conditioning, my partner and I finally bought one. Before that, we would sit in front of fans, or, even better, plunge into the Don Valley ravine to beat the summer heat. It was there, leafy trees above me, that I would find relief. 

I thought about this as I watched British Columbians deal with an extreme heat event. I know from growing up in Vancouver that few people have air conditioners, which made me think about the role parks play in heat crises–and who has access to life-saving trees and green space. 

Elbow River, Calgary. Photo Credit: James Tworow (FlickrCC)

It’s no secret that our cities are getting hotter due to climate change and that Canada is warming faster than the rest of the world. By building concrete cities, we’ve created “urban heat islands” that absorb the sun’s heat, keeping temperatures hot into the night. 

This extreme heat is uncomfortable, but also deadly. More than 700 people died during BC’s recent heat wave. In 2018, 66 people died in a Montreal heat wave. People who lived in neighbourhoods deemed urban heat islands were twice as likely to die.  

This will only get worse. As we outlined in our recent Canadian City Parks Report, Health Canada notes that by the middle of the 21st century the number of days with temperatures over 30 degrees will double in Canadian cities. A 2018 study found that, depending on mitigation measures, Canada could see a rise of 45% to 455% in heat-related deaths between 2031 and 2080. If that’s not a national health crisis, I’m not sure what is.  

Green spaces are fundamental to reducing the urban heat island effect. We all know the bliss of standing under a shady tree, but vegetation also helps cool cities through evapotranspiration. This is basically when plants sweat, cooling the air around them. 

Not every park is the same. A review by the David Suzuki Foundation found that size, (bigger parks extended benefits), shape (irregular-shaped parks increase cooling effects), and connectivity (closer together parks were cooler) have big impacts on the heat-mitigating powers of parks.

Even plantings make a difference. Sorry to the lawn lovers, but densely planted naturalized meadows are better at cooling than grass. This makes projects like Vancouver’s recent low-mow meadows, which naturalize park lawns to support biodiversity, an important climate resilience project. 

Streetside garden, Vancouver. Photo Credit: Jake Tobin Garrett.

Parks also provide places for people to build social connections. This can quickly become life-saving during a crisis, where people who may be isolated and more vulnerable to heat–like older adults–are able to draw on connections for help. As one study put it, the social connections afforded by parks “may be a lifeline [for isolated individuals] in extreme temperatures.”

This highlights the importance of redressing inequities in high-quality green space access–another topic explored in Park People’s 2021 Canadian City Parks Report.

Multiple studies have shown that wealthier, often whiter, neighbourhoods are also greener. As Health Canada notes, neighbourhoods most affected by heat “disproportionately impact marginalized populations and residents of lower-income communities” who have less green space. 

Even when trees exist, they are healthier in wealthier neighbourhoods. A Canadian study found neighbourhoods with high socioeconomic vulnerability had fewer trees and less resilient canopies. 

As journalist Jen St. Denis pointed out, urban heat islands map onto areas of Vancouver based on income, with wealthier west side neighbourhoods greener and thus cooler than east side neighbourhoods. 

Canadian cities are beginning to step up with more equity-focused plans that, with proper funding and implementation, could start to redress these inequities. 

Vancouver’s recent parks master plan includes a mapping tool using indicators such as tree canopy coverage to prioritize green space investments. Ontario’s Peel Region has also done heat mapping, noting that this could be used to target improvements for vulnerable populations. 

Meeting this challenge will require an all-hands-on-deck approach. It must involve parks departments, but also streets, city planning, and community organizations. Federal funding for green infrastructure and tree planting should contain equity guidance to ensure improvements are made in the areas that need them first. 

If we all work together, we can create cooler, greener, more equitable cities. 

Cover image: Corktown Common, Toronto. Photo Credit: Jake Tobin Garrett

This article first appeared on TorontoStar.com, July 7, 2021.