Brown University, Providence, Rhode Island
A conservation biologist considers the role of nature reserves in a warming world.
Over the next 100 years, climate change is expected to extirpate many species from their current locations. As a scientist who studies these effects, I was surprised by the magnitude of a recent projection. Of the nearly 500 protected reserves in the San Francisco Bay area of California, more than 98% are expected to have entirely different summer temperatures going forwards, with no overlap between the warmest conditions found within these areas now and the coolest conditions in the future.
David Ackerly at the University of California, Berkeley, and his team studied the pace of climate change in the western United States (D. D. Ackerly et al. Divers. Distrib. 16, 476–487; 2010). By mapping current temperatures and those projected by a moderate warming scenario, they found that the geographical locations of specific temperatures will move by as much as 4.9 kilometres per year. This means that conditions currently experienced at a particular location could shift by hundreds of kilometres in just 50 years.
These findings have important implications for the design and management of protected areas. With climate change, most reserves will not maintain conditions that are suitable for the set of species that exists there at present. To survive, many species will need to move, either on their own or with human assistance. Accommodating this will require a major change in the perceived role of nature reserves. Traditionally, these have been managed as ‘museums’ that maintain historically accurate compositions of species and ecosystems. In the future, we may need some reserves to function as ‘way stations’, with transient compositions of species. This may be the only way to promote the long-term conservation of species that can no longer survive in their present locales.