Global warming linked to caribou-calf mortality

Fewer caribou calves are being born and more of them are dying in West Greenland as a result of a warming climate. Click here for more information.

The phenomenon, called trophic mismatch, is a predicted consequence of climate change, in which the availability of food shifts in response to warming, whereas the timing of demand for those resources does not keep pace. Trophic mismatches have been documented in birds -- with the most famous example being the study on Dutch birds and their caterpillar prey that was highlighted in former Vice President Al Gore's film An Inconvenient Truth -- but, until now, the phenomenon had not been observed in terrestrial mammals. "Our work is the first documentation of a developing trophic mismatch in a terrestrial mammal as a result of climatic warming," said Post. "And the rapidity with which this mismatch has developed is eye-opening, to say the least."

While Post and Forchhammer think it is possible that caribou will respond to a warming climate by advancing the timing of their reproduction, they are not convinced that the species will be able to compensate fully for the rapid rates of temperature change that are yet to come. "They're a little behind the game already and future warming will make it even harder for them to catch up," said Post. "This factor is just one of many related to climate change -- such as thaw-freeze cycles, ice-crust formation, and severe storms -- that may make it difficult for caribou populations to persist at their former abundance."

This research was funded by the University of Alaska, the Penn State Institutes of Energy and the Environment, and the National Geographic Society Committee for Research and Exploration.

CONTACTS:
Eric Post: (doing field work in Denmark at the moment) (+) 45-4630-1958,
Barbara Kennedy (PIO): (+1) 814-863-4682,

IMAGES:

High-resolution photos are on the web at http://www.science.psu.edu/alert/Post5-2008.htm.