Future impact of global warming is worse when grazing animals are considered

The impact of global warming in the Arctic may differ from the predictions of computer models of the region, according to a pair of Penn State biologists. The team — which includes Eric Post, a Penn State associate professor of biology, and Christian Pederson, a Penn State graduate student — has shown that grazing animals will play a key role in reducing the anticipated expansion of shrub growth in the region, thus limiting their predicted and beneficial carbon-absorbing effect. The team’s results will be published in the online Early Edition of the journal Proceedings of the National Academy of Sciences sometime between 18 and 22 August 2008.

Most computer models indicate that shrubs will thrive and spread as a result of global warming. And because shrubs have an increased ability over grasses and other small plants to absorb the greenhouse gas carbon dioxide, many scientists believe that shrubs will absorb some of this carbon dioxide and, thereby, lessen the impact of climate change. While Post and Pederson agree that global warming will promote the growth of shrubs, they argue that grazing by muskoxen and caribou will reduce the carbon-mitigating benefit of the plants.

Physorg