New Greenbelt Foundation report reveals critical cooling effect of tree canopies in Markham, Woodbridge

York Region neighbourhoods studied for impact of green space on health, economy and climate change

Yorkregion.com
Aug. 25, 2023
Kim Zazour

Most people these days understand the importance of trees -- especially after this summer of record-breaking heat, forest fires and the world staring down the barrel of climate change.

Now a new study, centred in York Region, attempts to quantify that importance -- both in terms of the economy and communities’ health.

We’ve all felt it this summer, the multiple heat waves and worrisome news reports, but scientists say it will only get worse.

Within 25 years, extreme heat events in the GTA are predicted to rise from 20 days per year to 66 days per year, leading to increased risk of heat-related illnesses and death.

One of the bigger dangers facing residents in this region is the “heat island effect” -- when buildings and paved surfaces amplify and trap heat, making it significantly warmer than surrounding rural areas by absorbing heat during the day, radiating it at night.

Even short-term increases in outdoor heat stress can result in higher mortality rates and increased health system use, the report said.

The research, conducted in two York Region residential neighbourhoods, asks, what happens when urban areas increase greenery?

It turns out, a lot.

Lowering temperature through greenery can reduce health risks, lower energy use and increase worker productivity, the study found.

Researchers with University of Waterloo and Toronto Metropolitan University applied a model to case study two typical neighbourhoods in Markham Village and East Woodbridge, looking at meteorological data and health records data to see what happens in extreme heat events with human illness, energy consumption and health costs.

The Markham and Woodbridge communities were chosen as representative southern Ontario neighbourhoods that have vulnerable populations and are experiencing urban heat islands -- but have planting space available to mitigate the impacts of heat events.

The study found that when communities increase greenery cover, there are multiple economic and health benefits, said Edward McDonnell, the foundation’s chief executive officer.

For example, in extreme weather, a moderate increase in tree plantings (about 50 per cent of allowable area) would reduce mortality by one person every 10 days, while an intense green cover increase (using all available space for planting including parks, roadsides and spaces between buildings) would reduce deaths by two persons every 10 days.

It’s the kind of information that could help decision-makers look to natural solutions for the challenges facing our world, McDonnell said.

“Everyone can understand intuitively tree and other green cover can do a lot of things for communities, but how do you then translate that into a more detailed or tactical understanding that is useful for policymakers, who have a variety of demands on them in terms of how they approach building their community?”

This report is intended to help them understand the practical, financial and other human benefits, he said.

“This kind of green cover is critically important from a whole variety of perspectives,” McDonnell said.

“Humans like to be in and around green areas, and this study says to policymakers, that’s great, but think about it beyond some of the more traditional ways and understand it as a real tool for climate adaptation.”

That can include programs like the foundation's partnership with Forest Ontario -- planting a million trees in Greenbelt areas -- and more focused approaches like that of LEAF (Local Enhancement and Appreciation of Forests), providing native trees and shrubs to property owners at a subsidized cost.

The City of Markham is collaborating with York Region, offering LEAF's discounted trees with professional arborist advice and tree-care instructions.

In the case of southern Ontario, the Greenbelt is an “amazing advantage,” a head start for surrounding urban areas, McDonnell said.

“Certainly in my household, and people I talk to, there is a high degree of attention being paid to climate change and, frankly, a certain degree of anxiety. What we want to do is move beyond thinking and worrying to what can we actually do.”