National Public Radio: ARI SHAPIRO, HOST: In a couple of weeks the world will focus on Paris again for entirely different reasons. President Obama and representatives from nearly 200 other countries will be there trying to agree on a deal to limit carbon emissions and slow climate change. Todd Stern is the chief negotiator for the U.S., his title is Special Envoy for Climate Change, and he joins us now to preview the Paris talks. Thanks for being here. TODD STERN: Thank very much Ari. SHAPIRO: This summit begins November...