How fast do we need to move—and how fast can we move? These are questions for scientists and engineers, but also social scientists and activists to answer. Almost daily we can get some new assessment from those who study ice caps or monitor sea level rise: it’s melting ‘faster than expected,’ it’s rising ‘past the upper bound of earlier predictions.’ We’re seeing floods and firestorms on a scale that no one predicted even a decade or two ago—the damage that was once foreseen for 2080 or 2150 seems to be occurring already. In the autumn of 2018, the IPCC offered at least a few suggestions on speed: to hit the targets set in Paris, it appears we’ll need to have cut fossil fuel use in half by the end of the next decade. But can we do that? Is it technically possible, and is it politically achievable? How do we avoid the pitfalls that came when, say, the French raised gas prices, helping set off the Yellow Vests protests? Does the Green New Deal offer the broad outline of a new political dispensation that might allow us to move with speed and social cohesion? Science informs the climate crisis—but so does political science. This conversation can’t be postponed because action can’t be postponed.

With Mark Jacobson, Romain Felli, Priscillia Ludosky, and others. Moderated by Bill McKibben.