“Pros and Cons of US-Canada Oil Pipeline.” Living on Earth. June 10th, 2011: “GELLERMAN: But this oil, while it might be good for national security and energy independence, is also very, very polluting in terms of greenhouse gasses. CARSON: It is right now. It does release more greenhouse gasses than other forms of oil production, than more traditional forms of oil production. And that too is one of the issues that many of the environmentalists have raised in complaining about the Keystone XL. That, you know, they’re opposed to tar sands development for that very reason.”