Vancouver’s tree canopy is expanding to help protect from extreme heat

A tree canopy shades the ground from the sun's heat, like this cluster of trees.

The city of Vancouver is looking to plant more trees to help deal with extreme heat events.

Since the 2021 heat dome in B.C., which saw 619 heat-related deaths in the span of a week, the city has been taking measures to prepare residents and infrastructure for warmer summer temperatures.

One of these measures is expanding the existing tree canopy. A tree canopy includes the layers of leaves, branches, and stems of trees that shelter the ground from sun. The canopy provides ample shade on city streets and lowers the air temperature through evapotranspiration, the process that adds water to the air through evaporation from plants and surrounding soil.

Additionally, urban tree canopies help combat the urban heat island (UHI) effect. The UHI effect is what happens when cities get hotter on average than their rural counterparts due to closely packed buildings and paved surfaces. This “gray infrastructure” absorbs the sun’s heat throughout the day, which ends up not only keeping the city hotter during the day, but raising the nighttime temperature as buildings, sidewalks, and city streets release heat through the evening.

These canopies are effective in combating rising heat from climate change in urban areas, but only when they’re organized meaningfully. In Vancouver, the areas with the most canopy cover are more affluent neighbourhoods. The city’s 2024-25 Climate Change Adaptation Strategy recognizes the disparity in canopy coverage.

“There is a documented spatial overlap between areas of Vancouver with the lowest tree canopy cover percentages, lowest income areas and the areas with the highest surface temperatures,” the report states.

A lack of investment in shading low-income areas may raise the risk factor for heat-related health events in these neighbourhoods in the future. On Wednesday, Coun. Lucy Maloney brought a motion before council intending to proactively protect residents from dangerous heat.

“In general terms, we know that there is a direct correlation, unfortunately, in our city between tree canopy and socioeconomic status of residence,” said Maloney, “that means that more wealthy areas have better tree coverage, and the most vulnerable people that live in the poorest areas of the city have the least tree canopy.”

According to the latest update to the Urban Forest Strategy, the city is staying on target with its goals of expanding the canopy to areas that need it most, but emphasizes there are opportunities to improve when it comes to retaining trees, soil, and ecological corridors with development. The update stresses the importance of integrating nature into urban designs to prevent overdevelopment and preserve the urban forest’s health and resilience.

This summer is expected to be one of the hottest on record, and as subsequent years are projected to continually heat up, tree canopies are more important than ever.

“There’s a saying that the best time to plant a tree was 20 years ago, and the second-best time is right now,” Maloney said.

Vancouver aims to achieve 30 per cent canopy cover throughout the city by 2050.