Projected distributions of novel and disappearing climates by 2100 AD

doi:10.1073/pnas.0606292104

Projected distributions of novel and disappearing climates by 2100 AD

*Department of Geography, 550 North Park Street, University of Wisconsin, Madison, WI 53706;
^†Center for Climatic Research and
^¶Department of Atmospheric and Oceanic Sciences, 1225 West Dayton Street, University of Wisconsin, Madison, WI 53706; and
^§Department of Botany, 1000 East University Avenue, University of Wyoming, Laramie, WY 82071

Edited by Stephen H. Schneider, Stanford University, Stanford, CA, and approved January 30, 2007 (received for review July 24, 2006)

Abstract

Key risks associated with projected climate trends for the 21st century include the prospects of future climate states with no current analog and the disappearance of some extant climates. Because climate is a primary control on species distributions and ecosystem processes, novel 21st-century climates may promote formation of novel species associations and other ecological surprises, whereas the disappearance of some extant climates increases risk of extinction for species with narrow geographic or climatic distributions and disruption of existing communities. Here we analyze multimodel ensembles for the A2 and B1 emission scenarios produced for the fourth assessment report of the Intergovernmental Panel on Climate Change, with the goal of identifying regions projected to experience (i) high magnitudes of local climate change, (ii) development of novel 21st-century climates, and/or (iii) the disappearance of extant climates. Novel climates are projected to develop primarily in the tropics and subtropics, whereas disappearing climates are concentrated in tropical montane regions and the poleward portions of continents. Under the high-end A2 scenario, 12–39% and 10–48% of the Earth's terrestrial surface may respectively experience novel and disappearing climates by 2100 AD. Corresponding projections for the low-end B1 scenario are 4–20% and 4–20%. Dispersal limitations increase the risk that species will experience the loss of extant climates or the occurrence of novel climates. There is a close correspondence between regions with globally disappearing climates and previously identified biodiversity hotspots; for these regions, standard conservation solutions (e.g., assisted migration and networked reserves) may be insufficient to preserve biodiversity.

Footnotes

^‡To whom correspondence should be addressed. E-mail: jww{at}geography.wisc.edu
Author contributions: J.W.W. and S.T.J. designed research; J.W.W. performed research; J.W.W. and J.E.K. analyzed data; and J.W.W. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0606292104/DC1.
Abbreviations:

IPCC,

Intergovernmental Panel on Climate Change;

SED,

standardized Euclidean distance.