(60 word min, no cut and paste, cite refs "no wiki") It has been argued that the Keystone XL pipeline, which would increase the imports of oil from

(60 word min, no cut and paste, cite refs "no wiki")It has been argued that the Keystone XL pipeline, which would increase the imports of oil from Canadian tar sands would lower the price of gas in the US, but that it would do so by increasing the relative carbon footprint of that fuel. Would the pipeline actually have an impact on the price of gas? Why is that oil more carbon-intensive than oil from other sources?