Bill McKibben's Battle Against the Keystone XL Pipeline

Every month, Bill McKibben gets dozens of e-mails from pseudo-scientists—or perhaps actual scientists, for all he knows—describing plans to build perpetual motion machines. The senders want McKibben to help them secure financing to build these contraptions, which they claim will solve the world’s energy needs and save the planet. He took the first few of these requests seriously enough to at least ponder before deleting. Now he gets so many he doesn’t even read the descriptions or business plans, though he can’t shake a certain nagging guilt. “My heart breaks a little each time,” he says. “What if someone has actually figured it out?”

It’s precisely because global climate change is such a huge, complex, and costly problem that McKibben, 52, has become a tribune for those trying to solve it. Formerly a magazine journalist and writer of ruminative books about the environment and other issues, he’s now, at least in the U.S., the environmental movement’s most influential spokesman. As the founder of the advocacy organization 350.org, McKibben has spent the last five years traveling the world to raise awareness about climate change, leading acts of civil disobedience and urging academic institutions to divest their portfolios of stock held in fossil-fuel companies. He didn’t seek the role, nor does he particularly relish it. If he could, he would retreat to his solar-paneled house in Vermont tomorrow to write more books. But time, McKibben and the best scientists insist, has run out.