MINUTES after America’s State Department declared on January 31st that a proposed cross-border oil-pipeline would have little environmental impact, Canada’s ruling Conservatives posted an online ad bluntly directing Barack Obama to “approve Keystone XL now”. It is not the first time that Canada has dropped the diplomatic niceties when pressing Mr Obama to approve the Keystone pipeline, which would carry crude from Alberta’s tar sands to refineries on the Texas coast. Stephen Harper, Canada’s prime minister, has previously threatened to sell the oil to Asia, called approval a “no-brainer” and insisted he “would not take no for an answer”. But Mr Obama seems to be in no rush. Developing the tar sands and exporting its oil is a priority for Mr Harper, whose political roots lie in energy-rich Alberta. The pipeline, which would carry up to 730,000 barrels a day (b/d) of Alberta crude and an additional 100,000 b/d […]