›› Jan Firstbrook
Our city’s mature trees will play an important role as the climate changes and it becomes hotter and drier. In the City of Victoria’s Community Climate Risk and Vulnerability Summary Report, the highest risk is hotter, drier summers which lead to increased drought and more frequent heat events leading to health impacts on vulnerable populations. The heat wave in June last year was a wakeup call as there were 570 extra deaths than usual in B.C.—mostly elderly and small children. In Fernwood, many people are living in older homes and are at risk for heat-related stress and illness.
How do trees keep us cool?
Leafy canopies provide shade that prevents the sun from heating our buildings and man-made surfaces such as roads and sidewalks.
Without shade, an urban heat island develops as the concrete and pavement retain heal and radiate it all day and night, creating air temperatures up to 12 degrees C hotter. Surface temperatures in cars and other objects can be 30 degrees C hotter—as we all know when we park in the sun.
Trees also absorb trapped heat. Through transpiration, water within the tree is released as water vapour, which cools the air and lowers the surrounding temperature.
We need mature trees not only in parks but in our yards and on our streets where we live to provide natural air conditioning. Most of us do not have air conditioners to keep us cool in our homes and rely on trees to provide shade and cool the air temperature around us. Although planting new trees is worthwhile to capture carbon, it will take decades for these trees to provide the cooling benefits of one large Garry oak, maple, or Douglas fir.
How many trees are there in Victoria?
Victoria has approximately 150,000 trees of which 33,000 are public trees located in parks and boulevards. Private trees are protected by the new Tree Protection Bylaw unless the trees are within a building footprint. A private tree that is 30 cm in diameter (a medium pizza) at chest height is not allowed to be cut down without a permit from the City’s Parks department.
How many trees have been planted in the past 2 years?
To find out, look up the City of Victoria ‘Trees in the City Challenge’ Tree Tracker to discover that the City has planted 1,237 trees and 96 are in Fernwood. Homeowners can add their newly planted trees to the list.
Trees in our neighbourhoods are not only air conditioners but are also critical infrastructure in fighting climate change. It is expected that extreme heat events will increase and therefore, it is even more important to protect our mature trees. Retaining mature trees and planting new trees is one of the most effective and inexpensive ways to help mitigate climate change.