Cities and Climate Change: Toronto

The urgency of finding appropriate climate change mitigation and adaptation strategies for the long-run has become a major topic of concern across the globe. As the world has yet to agree on which strategies to adopt, cities and local governments have taken it upon themselves to do so.

In Toronto, the frequency of extreme weather events over the last 25 years has intensified. Since 1986, the city has seen eight important storms, each characterized by rainfalls exceeding those of storms which would only occur every quarter of century. There is concern that these extreme weather patterns will persevere or intensify in the future.

Many cities are slowly starting to realize that greenhouse gas emissions should not be the only focal point of their climate change mitigation strategies, as changing weather patterns are now also presenting themselves as threat for several major cities across the continent.

In 2005, Toronto was plagued with an important storm, which caused significant damage. The rainfalls inflicted on the city led to flooded basements, ruined cars, road decay, and the destruction of a sanitary sewer line as well as other major infrastructures. As a consequence, raw sewage was sent into a creek, posing a severe public health risk. Heavy rainfalls overwhelm sewage systems, sending pollutants and other toxic emissions into local water, leading to a situation known as Combined Sewer Overflow (CSO).

As rainfall patterns increase, controlling and managing Combined Sewer Overflow in accordance with the U.S. Environmental Protection Agency’s guidelines will become challenging.

To control Combined Sewer Overflow, the city of Toronto adopted the Wet Weather Flow Master Plan in 2003, which spans over a period of 25 years. As described by the city of Toronto: “the goal of the [Wet Weather Flow Master Plan] is to reduce and ultimately eliminate the adverse impacts of wet weather flow, which is runoff generated when it rains or snows, to protect our environment and improve the ecosystem health of the watersheds”.  

Toronto’s Plan focuses on putting in place both ‘green’ infrastructure projects, aimed at replicating natural processes, and ‘grey’ infrastructure projects, which focus on developing engineered facilities and structures. The plan, which will cost an annual $42 million, focuses mainly on water quality, water quantity, natural areas and wildlife and sewer system.

Some of the campaigns in Toronto’s plan include: improving the beach water quality, restoring stream and aquatic habitats, encouraging the construction of green roofs, tree planting and a basement flooding protection among other things. The Wet Weather Flow Master Plan has already showed turnaround: for instance, close to three-quarters of Toronto’s beaches now have good quality standards.

What is your city doing? Is it as ambitious as Toronto?