Bill McKibben contends that human beings are engaged in creating what he calls “Earth 2.0”—or “Eaarth”—a planet substantially different from the one that has nurtured life for millions of years—and human life for thousands of years. Recently, the conservative British newsweekly The Economist agreed. “Welcome to the Anthropocene,” it said on its cover. And in two articles inside—here and here—it described the ways that human beings are creating a new planet less hospitable to life—and especially to human life as we know it. People don’t just create environmental problems; now they’re creating a new planet—or, more precisely, a new ecological regime on an old planet. If you ever wondered if it’s time for activism, these articles should answer the question for you.