The State Department is preparing its final report on the environmental impact of the Keystone XL pipeline. In a speech last week, President Barack Obama tied his approval of the project to net carbon emissions. The president said, "our national interest will be served only if this project does not significantly exacerbate the problem of carbon pollution." A number of analysts interpreted the speech as laying the groundwork for approval. Others are convinced the president was signaling his intended rejection. For this month's Environmental Outlook, Diane and her guests discuss the proposed tar sands pipeline from Canada to the Gulf Coast.