President Obama has said the Keystone XL pipeline can only go ahead if it doesn't "significantly increase" U.S. greenhouse gas emissions. There's enough wiggle room in there to delight almost everybody.
Define "significantly." There you go. What does it mean if you export the really filthy petroleum coke or petcoke bitumen refining by-product to Asia and let them burn it? Is that okay? Does that just go on someone else's carbon books and off America's?
And in a country with the rapacious energy consumption of the United States anything "significant" would be huge almost anywhere else.