Earth's biodiversity is mostly in the tropics, and most tropical species can survive within only a narrow temperature range. That's because the environment they're adapted to is fairly constant year-round.

As global temperature warms, tropical animals are likely to feel the effects in unpredictable ways. Perhaps most at risk are species with small habitats in the tropical mountains. Some are moving to higher ground in search of cooler conditions—but those already living near summits may find themselves with nowhere to go.

Out of room

Chameleon (Calumma tsaratanense)

Chris Raxworthy/AMNH

The chameleon on display in the exhibit, Calumma tsaratanense, is found nowhere on Earth other than the island of Madagascar, off the southeast coast of Africa (map). And on that island, they are found nowhere but the remote Tsaratanana massif, the highest peak in Madagascar.

But even there, the chameleons aren't safe. Warming trends in Madagascar equal or exceed global averages. And scientists studying reptile and amphibian species found an average uphill migration that almost exactly matched what the animals needed to offset that temperature increase. The researchers predict that a 1.7°C (3°F) rise would be enough to drive to extinction endemic species living within 300 meters (1,000 feet) of summits all over the island.

On Borrowed Time?

The spotted lined gecko (Phelsuma lineata punctulata) lives only within 600 meters of Madagascar's highest peak. Like many mountain-dwelling tropical animals, it is vulnerable to habitat loss caused by projected warming.

Silent

In the past, protecting species has meant protecting habitat from development. But even a protected habitat like this region in northeastern Madagascar may be lost for inhabitants that cannot adapt to climate change.