The Switch 3 | Bill McKibben: One big thing is going right

For 40 years, environmentalist and author Bill McKibben has chronicled the worsening climate crisis and politicians' failure to stop it. But now, for the first time, he says he can actually see a path forward. In the third and final part of our special miniseries, The Switch, we ask him what that path looks like – and what still threatens to derail it.