Frogs of South America Can't Take the Heat

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There aren't a whole lot of global warming skeptics left, but those who still need some convincing should take a look at the frogs of Central and South America. According to a new study in the journal Nature, the little critters are dying fast, and climate change is to blame.

There are a number of reasons humans should care about frogs, not the least being that they're so-called indicator species—particularly sensitive animals that are the first to die when climate goes awry. As such they can warn us of problems when there still might be time to fix things. Biologists know that since 1979, two-thirds of 110 species of frogs have vanished in the American tropics. J. Alan Pounds, a resident biologist at the Monte Verde Cloud Forest Preserve in Costa Rica, wanted to determine if climate is indeed to blame. To do so, he and his colleagues studied voluminous records of frog extinctions from 1979 to 1998 and compared them with records of atmospheric and ocean temperatures in the same period. The results: 80% of species deaths indeed occured after especially warm years, with the overheated 1987 claiming five species all by itself.

Pounds and his colleagues believe it's not the heat specifically that's causing the deaths, but rather a fungus that attacks frogs and thrives as the climate changes. Paradoxically, the fungus prefers things cooler rather than hotter, but planetary heating actually results in daytime cooling of the frogs' and fungus's habitat since it leads to more evaporation, which in turn produces shade-producing clouds. The best way to stabilize all of the thermometer fluctuations is dial back the greenhouse gasses. Frogs, after all, are only the beginning.