Ontario has joined the Western Climate Initiative, a regional carbon-trading agreement with a goal of cutting greenhouse-gas emissions 15 percent below 2005 levels by 2020. The province joins seven U.S. states (Arizona, California, Montana, New Mexico, Oregon, Utah, and Washington) and three Canadian counterparts (British Columbia, Manitoba, and Quebec). For those folks not up on their Canadian know-how (so, all Americans): Ontario is Canada’s most populous province; with its participation, the WCI represents two-thirds of Canada’s population and an impressive 73 percent of its GDP. The WCI and other regional agreements in the Midwest and Northeast were spurred by frustration with a lack of federal action on climate change; similarly, Ontario Premier Dalton McGuinty explained that Canada’s global-warming policy “doesn’t satisfy all Canadians, so we see provinces making their own efforts to assume their responsibilities as global citizens.”