Amphibians live in two different media, air and water.
Thus, any widespread reduction in their numbers is likely a warning to us that all is not well with the environment. And apparently, all is not well. Recent research has discovered that frog populations the world over are plummeting, often in the most pristine environments, where habitat destruction, introduced predators, or pollution cannot have been the cause. This simultaneous decrease among so many species points to a global phenomenon-perhaps more intense exposure to UV rays from ozone depletion, or some newly evolved disease, or something we haven't even thought of yet. Whatever the cause, chances are that if it kills frogs, it could also threaten other species.