Autumn 2017 / Leading Edge
How Much Methane?

A U of T study aims to create the most accurate estimate yet of Toronto’s greenhouse gas emissions


Photo of Colin Arrowsmith biking along Huron Street, pulling a device.

Second-year student Colin Arrowsmith bikes along Huron Street, pulling a device to measure greenhouse gas emissions on U of T’s St. George campus. Photo: Ian Patterson.

Colin Arrowsmith spent part of his summer cycling – not for fun or exercise, but for science. As part of a research placement with U of T physics professor Debra Wunch, the second-year student criss-crossed campus on a bike, towing a buggy with a bright yellow box inside – a spectrometer used to measure the concentration of greenhouse gases at precise locations.

The project, which got underway earlier this year, marks a new and ambitious attempt to calculate the city’s emissions of methane, carbon dioxide and other gases based on atmospheric measurements rather than on estimates from industry.

Wunch says the information will help pinpoint the biggest sources of Toronto’s emissions. The data could prove vital as the city strives to cut its contributions to greenhouse gases to one-fifth of 1990 levels by 2050. It will also enable the city to zoom in on where its reduction efforts are needed most – and to notify organizations about fixing previously unnoticed leaks. As Wunch observes, this is not only good for the planet, it’s good for the organization.

In addition to using the mobile equipment, Wunch and her team will install spectrometers at the tops of two buildings – one upwind and one downwind from the city. These will provide readings of greenhouse gases in a column from ground level right up to the top of the atmosphere, enabling the researchers to measure the city’s overall emissions.

Wunch has conducted a similar study in Los Angeles, which found methane emissions to be higher than had been previously estimated. The carbon dioxide levels measured were about the same as estimates, she says.

The Toronto study is just beginning, but Wunch hopes that it leads to a long-term effort to monitor greenhouse gases in Toronto. “You want to actually be able to watch as the emissions reductions occur over time, and see that the city’s efforts are working,” she says.

Debra Wunch’s research is supported by the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation and the Ontario Research Fund.


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