Would-be eco-friendly metropolises know it's not easy being green. And it's near impossible if you're a sole Canadian municipality in one of the country's regional urban supercities.
A Pembina Institute report published Wednesday finds that although individual cities are taking steps to combat climate change, the regions those cities are a part of remain polluting carbon gluttons.
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Municipal governments acting on their own risk missing the regional forest for the city-specific trees - and that's hampering their ability to make a real difference in shrinking carbon footprints.
And Toronto - centre of the sprawling urban mass that's home of the vast majority of Ontario's population and responsible for the lion's share of its greenhouse gas emissions - is no exception.
Policymakers ignore the bigger picture at their peril, says University of Toronto professor Chris Kennedy who has mapped yawning gaps in emission rates between Toronto-area neighbourhoods.
The Pembina study found that although the city of Toronto has succeeded in some areas, once the larger region was factored in, those initiatives didn't have as much of an impact.
"In this day and age, it doesn't come down to the city: It comes down to the big urban areas," said Pembina Institute spokeswoman Cherise Burda.
"The fight against climate change will be fought and won - or lost - in the suburban areas, because that's where all the greenhouse gases are coming from. That's where the driving is taking place."
Toronto didn't fare too badly in the survey, which also looked at environmental data from the Vancouver, Montreal, Calgary, Edmonton and Ottawa urban areas: A high proportion of the GTA's population lives in medium- or high-density neighbourhoods; the downtown core performs respectably when it comes to bike and transit use.
But people living in the Big Smoke also have the farthest commutes of anyone in any of the urban hubs studied.
Toronto Mayor David Miller has championed the role of cities in the fight against climate change. In an ever-urbanizing world where a growing proportion of emissions come from cities, the argument goes, it only makes sense for local governments to lead the charge.
But as long as cities act alone, says University of Toronto professor Douglas Macdonald, they're limited by economic, political and physical boundaries.
Lawson Oates, head of Toronto's environment office, said there's a need for more integrative planning when it comes to fighting climate change. But cities need the power to make local, progressive decisions of their own, he noted.
"I think that the generation of ideas, the energy that comes out of individual municipalities, is very. important. It's important that we don't lose that in the mix."
The carbon-footprint differences between the Toronto area's neighbourhoods are stark: A 2007 study Prof. Kennedy co-authored found that while some poorer areas of Toronto only created 3.1 tonnes of greenhouse gas emissions per capita, the wealthiest and most far-flung suburban areas used 13.1.
"To really to reduce the carbon footprint of a city is very challenging," Prof. Kennedy said.
"A city could go it alone, but it would be somewhat false, right? It would be this little sort of island of green in the middle of this urban sprawl."