Blue and Green: Former US president Jimmy Carter has urged current president Barack Obama and secretary of state John Kerry to reject the construction of the controversial Keystone XL pipeline.
The proposed project would link Canadas tar sands to refineries in Texas and could transport 800,000 barrels of oil per day. The development was originally proposed in 2008, but the environmental and economic impact of the pipeline has been debated.
A letter signed by Carter, along with nine other Nobel prize laureates,...