Professor Robert Stavins, Director of the Harvard Project on Climate Agreements out of the Kennedy School’s Belfer Center, explains why the COP21 in Paris is a critical step in addressing anthropogenic global climate change. He discusses the history of past climate summits and lays out both his markers for success and potential impediments to a deal.

More from Professor Stavins and other Kennedy School scholars can be found at http://hkscop21paris.tumblr.com.