Yale Environment 360: The U.S. State Department's final environmental review of the Keystone XL Pipeline may have underestimated carbon dioxide emissions associated with the pipeline by as much as four times, according to a new study published in Nature Climate Change. The addition of Keystone XL crude oil to the market will drive global oil prices down, the authors say, which in turn will increase demand for oil worldwide by as much as 0.6 barrels for every barrel of Keystone XL oil added to the market. The extra oil...