Science 322, 258–261 (2008)


Lowland tropics could lose a substantial proportion of their plant and insect biodiversity by 2100, according to a new study. The tropics are predicted to warm by about 3 °C by the end of this century, which would shift current temperature zones 600 metres uphill. Until now, little attention has been paid to the impact of this shift on tropical inhabitants.

Ecologist Robert Colwell of the University of Connecticut and colleagues scaled a Costa Rican volcano, rising 2,900 metres above sea level, to determine the elevation ranges of 1,902 plant and insect species. Applying a simple model to their data, they conjecture that a regional temperature rise of 3.2 °C would shift many lowland occupants upward into completely new territory, possibly leaving low-lying rainforest bereft of many current inhabitants. With few replacements adapted to higher temperatures waiting in the wings, species richness in the region may be set to fall. At the same time, species living near the tip of the mountain will experience a contraction in their elevation range, increasing the risk of extinctions.

Although more research is needed to determine the tolerance of lowland species to temperature gains, it is clear that climate change poses a substantial threat to tropical biodiversity.