Bill McKibben, a journalist, writer, and climate change activist, discusses his most recent book, "Eaarth: Making a Life on a Tough New Planet." Twenty years ago, with his first book "The End of Nature," Bill McKibben offered one of the earliest warnings about global warming. Those warnings went mostly unheeded; now, he insists, we need to acknowledge that we've waited too long, and that massive change is not only unavoidable but already under way. Our old familiar globe is suddenly melting, drying, acidifying, flooding, and burning in ways that no human has ever seen. We've created, in very short order, a new planet, still recognizable but fundamentally different. We may as well call it Eaarth. That new planet is filled with new binds and traps. A changing world costs large sums to defend -- think of the money that went to repair New Orleans, or the trillions it will take to transform our energy systems. But the endless economic growth that could underwrite such largesse depends on the stable planet we've ma