Climate Change’s Invisible Victims

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Turn away, for a moment, from that iconic image of a sad polar bear slowly drifting out to sea on a melting floe of ice. In campaigns to raise awareness of the effects of climate change, animals in chilly locales have gotten an unfair share of attention, reports the Ecologist (April 2009). New research suggests that it’s tropical creatures that ought to be in the spotlight.

Most species in tropical climates are “thermal specialists,” explains the British environmental publication. They’ve evolved to live in a limited range of temperatures corresponding to a narrow band of elevation. Mountains, even hills, stymie many lowland species; they can’t bear the cooling effect that comes with ascending in altitude. Similarly, tropical mountaintop dwellers can’t physically bear to descend.

A 2008 study by researchers at the University of Connecticut predicts that as temperatures rise, tropical lowland creatures will begin migrating upward. Same goes for midland species. But many lowland critters, such as those who live in vast basins, will have nowhere to climb. The effect could be catastrophic: During a heat wave in 2002, biologists in Australia witnessed a heartbreaking die-off of flying foxes. As temperatures spiked, the animals sought shade, began panting and licking their fur, and then simply fell dead from the trees.

Mountaintop and highland species will be hit twice as hard. Heat evaporates the moisture-rich cloud cover on which these animals depend—and because they’re already at the top, there’s nowhere higher to go. For this reason, the white lemuroid possum, whose habitat is the cool Queensland rain­forest, 3,600 feet above sea level, would make a sharper poster animal for climate change. Polar bears deserve attention too, but thermal specialists are even more precipitously poised.