Climate change in the tropics: The end of the world as we know it?

As a broad scientific consensus in support of anthropogenic global warming emerged in the 1980s, a few biologists were quick to make predictions of the likely impacts in the tropics. Most conservation biologists, however, saw climate change as a much less immediate threat to tropical terrestrial ecosystems than deforestation, logging, and hunting. There has been a rapid shift in opinion in the last few years, with the widespread recognition that the climate is already changing at a rate that is relevant to current conservation actions in the tropics. Unfortunately, more than a decade of relative neglect of climate change research has left tropical biologists with little hard information on which to plan a response. The most widely used climate projections for the tropics do not represent the full range of model possibilities and do not reflect the current rates of greenhouse gas emission. The 2–3 °C rise that is commonly assumed could be 4–6, or even 7 °C, while projections for rainfall and other climate variables have still greater uncertainty. These climatic uncertainties are compounded by our ignorance about the potential biological consequences of these changes. It is very likely, however, that the majority of the tropics will soon be subject to climatic conditions that have not existed anywhere on Earth for millions of years. It’s a new world and all bets are off.

► Tropical conservationists have not seen climate change as the most immediate threat.
► Uncertainties in future climates and their consequences are higher in the tropics.
► Enough is known, however, to suggest that the impacts could be severe.