You've heard the bad joke right? If the earth were a bank it would be bailed out. We have been diddling while the planet gradually sizzles. Conferences from Kyoto to Copenhagen come and go. Not much happens. The US Congress? Well, the interests of big oil and coal come first, earth second. We have waited too long. Massive change is under way. For millennia the planet has been habitable and now it is melting, drying, and flooding in unprecedented ways. Leading environmentalist Lester Brown calls for "a wartime mobilization, an all-out response designed to avoid the destabilizing economic and political stresses that will come with unmanageable climate change. An emissions cut of 80 percent from today's levels by 2020, not 2050, would keep atmospheric carbon dioxide concentrations from exceeding 400 parts per million, setting the stage for getting back to 350."

Bill McKibben was one of the first to sound the alarm on climate change with his bestselling book The End of Nature. A scholar-in-residence at Middlebury College, he is a leading activist, journalist and author on the environment. His other books include The Age of Missing Information and Hope, Human and Wild, Deep Economy, and Eaarth. He is co-founder of 350.org.