Published on June 14, 2024 by Ethan Rotberg, Senior Communications Specialist, Evergreen
The expression “sunshine is the best medicine” feels misplaced in today’s climate crisis.
Scientists project that by 2050, the average annual temperature in Ontario could increase by approximately 3.3°C. By then, more than 20% of Earth’s population will be aged 60+, and hundreds of millions of seniors will be facing extreme heat risks.
While many of us may see a rise in temperature as an inconvenience or a discomfort, the problem is far worse. Between 1996 and 2010, a 5°C increase in daily temperature in Ontario caused an estimated four excess deaths per day.
Heatwaves are arguably the deadliest type of extreme weather event. In the U.K., heat waves caused more than 2,500 deaths in summer 2020; the 2010 heat wave in Moscow led to 11,000 deaths; and a heat wave that swept Europe in the summer of 2003 was the deadliest natural disaster to hit the continent in 50 years.
People in cities (where at least 80% of Canadians live) are feeling the heat especially, where rising temperatures are intensified due to the urban heat island effect.
With all the statistics and warnings, it’s difficult not to lose your cool. So, let’s find solace in the shade and talk about a solution: our urban forest.
While many people appreciate city trees for their aesthetic appeal, they also play a critical role in improving air quality, easing stormwater issues, providing essential habitats for wildlife and enhancing physical and mental health for residents. But perhaps their greatest benefit is reducing urban heat islands, which intensify extreme heat challenges in cities.
Urban heat islands are when cities experience higher temperatures than their rural surroundings due to human activities, reduced green space or dense infrastructure, especially from surfaces like asphalt and concrete that absorb and retain heat.
“Canada warmed by an average of 1.6°C between 1948 and 2012, roughly at double the global average rate of warming,” points out Zoya Sodhi, Senior Program Manager at Evergreen. “Cities across Canada are seeing pronounced effects from these heat waves due to the urban heat island effects prevalent in the built environment, with paved surfaces being 27-50 degrees Celsius hotter than the air.”
Green Infrastructure Ontario’s urban forest toolkit points out that trees are particularly crucial because of their ability to provide neighbourhood-level cooling. Even a very small increase in canopy cover could reduce heat-related ambulance calls by up to 80%.
So, how exactly do these barked beauties cool our concrete jungles?
It starts with shade, reducing the surface temperatures of roads, sidewalks and buildings. Trees also release water vapour through their leaves — this process, called evapotranspiration, can significantly lower local temperatures. Urban forests also improve air quality, which can help regulate temperatures by reducing the amount of heat-trapping pollutants in the atmosphere. And a strategically-placed tree can even lower energy consumption in buildings, lowering greenhouse gas emissions.
The majority of large Canadian cities have continued to lose tree canopy over the past 20 years, according to a Statistics Canada report that measured urban greenness.
But is there already a recent urban tree revolution underway? Several North American cities are setting lofty urban forestry goals, not just prioritizing total canopy cover but also addressing the inequitable distribution of the urban forest, often called “tree equity.” This ensures all communities, regardless of socioeconomic status or demographics, have equal access to the benefits provided by trees.
But challenges persist, including concerns over costs and maintenance, constraints posed by limited space and infrastructure conflicts and varying regional planning priorities. But knowing the impact of the urban forest helps make the case for using public funds stronger.
One undeniable fact: both residents and policymakers need the data to justify the investment.
“As cities are seeing more profound impacts of climate change, particularly extreme heat, they are looking at advanced technologies like GIS mapping, satellite imagery, IoT devices, drones and data analytics,” says Sodhi.
AI is already transforming our everyday lives. AI-generated music can go viral online; could it be used to tackle the climate crisis?
That question is what led to the launch of Evergreen’s AI for the Resilient City — a data visualization and analytics tool that has been developed in partnership with Gramener and funded in part by RBC Tech for Nature. Our aim is to help municipalities across Canada plan for and mitigate the impacts of extreme heat, particularly Urban Heat Islands (UHI) effects. It gives the power to local municipalities and regions to make informed decisions and support policy changes at the community level through data and technology.
The data visualization tool could be helpful to communities and local municipalities in fascinating ways, Sodhi points out.
“It can help with identifying UHI hotspots where more green interventions can help with coping with the impacts of extreme heat. It will showcase the cooling effect of parks, public spaces and natural assets, particularly water bodies and green cover. It can even help locate shading and cooling amenities to create higher standards for street trees and cooling in our warmest areas.”
Perhaps most critically, the tool is designed to assist community planners in making evidence-based decisions related to climate risk reduction for planning and infrastructure projects. Peel Region is currently undertaking several urban forest initiatives using the AI for the Resilient City tool, including an Urban Forest Strategy Update and an Urban Forest Management Plan.
“The tool incorporates Normalized Difference Vegetation Index (NDVI) in the application, which is a vegetation index that is widely used to quantify vegetation greenness,” Sodhi adds. “These NDVI maps can be used to identify areas where vegetation is needed as a way of mitigating the effects of extreme heat.”
For decades, the impacts of the climate crisis have largely been felt in parts of the planet that feel remote in comparison with Canada’s cities. But that’s changing before our eyes as the fallout from extreme weather and natural disasters begins to find its way into everyday urban life. Canadian cities are now facing increased extreme weather challenges and other crises. We need to invest in opportunities with the time and resources we have, and public spaces can offer a solution. Learn how you can support our work and invest in a healthy planet.
Whether we’re building better public spaces or improving community and climate resilience with data and technology, we are committed to working through a placekeeping lens. Being stewards of the land involves the active care and maintenance of a place; nurturing and preserving what is already there. Read our Civic-Indigenous Placekeeping and Partnership Building Toolkit for more information on placekeeping or to see case studies for best practices in placekeeping partnerships.
Visit our website to read more about the first two phases of the AI for the Resilient City program, and stay tuned for updates on how this initiative will unfold in more cities across Canada.
