New Republic: Climate change is one of the most critical issues facing the United States and the world. President Barack Obama has made it a top priority of his second term and a cornerstone of his legacy. He has passed some of the most sweeping environmental regulations of any president and laid the groundwork for a global climate change agreement in Paris. His decision to reject the Keystone XL pipeline secured his reputation as an environmentalist. Yet it will fall to Obamas successor to determine whether...