San Francisco Chronicle: Former President Jimmy Carter joined fellow Nobel laureates Wednesday in opposing Keystone XL, insisting that approving the pipeline would trigger "more climate upheaval" around the globe. In an open letter to President Obama and Secretary of State John Kerry, Carter and the nine other Nobel Peace Prize winners bluntly warned the leaders: "Your decision on the Keystone XL tar sands pipeline will define your climate legacy." The missive, published as an advertisement in Politico, represents the...