Humans Mitigate Climate Change Effects

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Science  14 Sep 2012:
Vol. 337, Issue 6100, pp. 1274
DOI: 10.1126/science.337.6100.1274-b

In the early 20th century, Joseph Grinnell, who cofounded the University of California's Museum of Vertebrate Zoology, initiated a series of biological surveys throughout the western United States. He and his colleagues could not have predicted the extent of climate change that we are experiencing in the 21st century, but their survey data have proven to be invaluable. Morelli et al. have used these data to determine how climate change has affected Belding's ground squirrel, a mountain meadow specialist. From resurveys of 74 of the same sites in California's Sierra Nevada Mountains, which were originally sampled between 1902 and 1966, they found that 31 of the ground squirrel populations have been extirpated; in addition, there was no evidence for their having colonized nearby suitable habitats. Next, the authors examined climate, landscape, and land-use data to identify causal factors for the observed range contraction and found that winter cold was the strongest positive predictor of population persistence: Both more frequent rain-on-snow events and a thinner insulating snow pack are known to harm montane mammals. Interestingly, they found a buffering effect of human activity, such as camping and agriculture, which locally increase food and water availability. Models based on these causal factors predict a continuing contraction of Belding's ground squirrel populations, with the most extreme outcome being a 99% loss of suitable habitat in California by 2080.

Proc. R. Soc. London Ser. B. 279, 10.1098/rspb.2012.1301 (2012).

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