I HOPE the president turns down the Keystone XL oil pipeline. (Who wants the U.S. to facilitate the dirtiest extraction of the dirtiest crude from tar sands in Canada’s far north?) But I don’t think he will. So I hope that Bill McKibben and his 350.org coalition go crazy. I’m talking chain-themselves-to-the-White-House-fence-stop-traffic-at-the-Capitol kind of crazy, because I think if we all make enough noise about this, we might be able to trade a lousy Keystone pipeline for some really good systemic responses to climate change. We don’t get such an opportunity often — namely, a second-term Democratic president who is under heavy pressure to approve a pipeline to create some jobs but who also has a green base that he can’t ignore. So cue up the protests, and pay no attention to people counseling rational and mature behavior. We need the president to be able to say to the G.O.P. oil lobby, “I’m going to approve this, but it will kill me with my base. Sasha and Malia won’t even be talking to me, so I’ve got to get something really big in return.”