TO ANY ENVIRONMENTALLY conscious American, building the Keystone XL oil pipeline doesn’t sound like a great deal: a new pipeline that would transport dirty tar sands crude from Canada, over the Great Plains and to the Gulf Coast. Why would America “double down” on Canadian oil, when it takes more water and energy — which means more pollution — to extract? Secretary of State Hillary Rodham Clinton, who will decide before the end of the year whether to approve the project, has to answer that question
