Living on Earth: CURWOOD: In his recent address on climate change, President Obama pledged not to approve the Keystone XL pipeline if it would add significantly to global warming. Many Keystone opponents heard that as a death-knell for the project, but the overall climate impact of the pipeline will depend on whether the diluted bitumen, dilbit, from the Canadian Tar Sands would be able to get to the market anyway. And there may be another way. According to the online publication InsideClimateNews, the Enbridge Company...