Thursday, 31 July 2008

Something Really Cool: Planting Trees Brings Urban Temperatures Down

It’s hot and sticky in our neighborhood today, but at least we can rest in the shade. That’s because planting and maintaining street trees has been a priority for decades in Outremont, which was separate municipality before 2002 when it merged with Montreal.

The larger city has just announced a program to encourage more green plantings, including trees, green roofs and bushes. Big asphalt expanses in shopping centres and industrial areas will be the main targets: asphalted areas can raise air temperatures by five to ten degrees Celsuis. Le Devoir reported Wednesday that already 30 businesses have signed on to the program, representing the planting of about 2,000 trees.

One of the striking things I found when I was working on Green City was the great impact of plantings on the quality of life in cities. São Paulo was one of the first to use satellite photos to map hotspots in the city. A team of far-sighted bureaucrats showed elected officials just how paving and tall buildings without compensatory plantings were changing the city’s climate. The result was a change in direction in the city's policy toward maintenance of street trees and plantings. Singapore has had aggressive planting programs for four decades, allowing this city of highrises to become a truly green city. (For more on efforts in both, see my posts on “Green in an Unruly Metropolis” and "Clean and Green." )

And it's good to remember what Jane Jacobs did after she and her friends finally stopped the Spadina freeway that threatened to cut through downtown Toronto: she raked up a lot of maple and slippery elm trees and scattered them over the excavation undertaken in preparation for the roadwork which never was done. (See Ideas that Matter, p. 120)

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