Two veteran environmental economists at MIT, John Reilly (left) and Henry "Jake" Jacoby, briefly outline a couple of the most important, and least appreciated, facts about human-driven climate change. One is that the system has enormous inertia, preventing any quick fix. Another is that deep uncertainty surrounds the most consequential aspects of what's to come (pace and extent of warming, sea-level rise, for instance). An informal interview recorded by Andy Revkin of http://propublica.org.