AAP: UP to 3000 species of amphibians face extinction, giving the world its greatest conservation challenge, a leading expert says. Chicago-based Amphibian Ark director Kevin Zippel said the looming crisis was entirely man-made and only human intervention could stop it. “This is really a major extinction crisis,” Dr Zippel said. “We’ve never seen a group like this singled out for extinction and what’s interesting is that this isn’t a natural phenomenon. “Everything …