med that goal in his Climate Action Plan.
According to the models used in Intergovernmental Panel on Climate Change analysis, we must keep atmospheric carbon dioxide concentrations below 450 parts per million to achieve the 2 degrees target. That's not possible if we maintain the status quo, much less bring online more and exceedingly dirty sources of fuel such as tar sands oil.
In a glaring omission, the Keystone XL review failed to factor in the 2 degrees limit, and assumed the continuation of business-as-usual practices for the next quarter century. We have almost no chance of meeting the 2 degree goal if any of the report's scenarios are realized.
Kerry's obligation is to determine what is in the national interest. For all its flaws, the report acknowledges that the tar sands that would get to market through Keystone XL could significantly worsen climate change. That's a risk that climate champions such as Kerry and Obama shouldn't be willing to take.