When it comes to the environment, it seems that political divisions in America only grow wider. According to a recent survey by the Pew Research Center, 90 percent of Democrats believe that the “country should do whatever it takes to protect the environment,” compared with 52 percent of Republicans. But it wasn’t always that way. American Experience spoke with environmental historian Naomi Oreskes, author of the book Merchants of Doubt, about the early days of environmental activism, and how it gained — and then lost — broad bipartisan support. By Cori Brosnahan.