Bill McKibben, Schumann Distinguished Professor in Residence at Middlebury College in Vermont, is a founder of the grassroots climate campaign 350.org, a 2014 recipient of the Right Livelihood Prize (aka the 'alternative Nobel') and the author of a dozen books about the environment, including his first, the seminal The End of Nature, published 25 years ago, and his most recent, Oil and Honey. (350.org)