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Even more dangerous, notes Don Melnick, head of the Center for Environmental Research and Conservation at Columbia University, is how doomsayers create a Chicken Little problem. "We need to bury the notion that the biological world is going to collapse and we're all going to be extinct," he says. "That's nonsense, and it can make people feel the situation is hopeless. We can't have people asking 'So why should we bother?'"