In Bonn, Germany, negotiators are trying to sharpen the fine points of the Paris Climate Accord, and US diplomats are in attendance. But they have limitations, given that President Trump has pledged to withdraw from the Accord. The US can't officially pull out until the year 2020. So what are US negotiators up to at this week's meetings? We ask Andrew Light, an architect of the Paris Accord for the Obama Administration. Now a distinguished senior fellow at the World Resources Institute, Light considers the roles of the US, China and California Governor Jerry Brown.