Science of summer: How many trees does it take to cool a city?

By Tom Spears, Ottawa Citizen, July 4, 2019

Postmedia’s popular Science of Summer series is back, in its usual on-again, off-again way. Today Tom Spears looks at new findings about how trees cool cities.

One summer day Carly Ziter hopped on her bicycle and set off to calculate how many trees it takes to cool down a city.

Cities form “heat islands” — zones where the temperature is higher than in the surrounding countryside because of all that asphalt and concrete. Trees help reduce the heat island effect. That much is old news.

But how many trees are enough?

Ziter, who teaches biology at Concordia University, was a PhD student at the University of Wisconsin-Madison when she began this work, back in 2016. She and her helpers loaded up their bikes with small, battery-powered mobile weather stations and pedalled around the city.

Connect with us