U.S. forests may not help in climate change fight

Margaret Evans - questions about
 U.S. forests being mature enough
 to help fight climate change.

North American forests will not fight climate change by absorbing carbon dioxide at levels once hoped for because the trees may not grow big enough, a study said.

The new research challenges previous studies that said trees could grow larger due to higher temperatures brought on by global warming, said the authors of the study published in the journal Ecology Letters.

Typically, up to a third of carbon-dioxide emissions from human activity, such as automobile driving or steel production, is absorbed by forests, the study's authors said. Carbon dioxide is the main greenhouse gas responsible for global warming.

But if temperatures get too high, tree growth is inhibited and the absorption rate diminishes, said senior author Margaret Evans, a professor at the University of Arizona in Tucson.

"There is a tipping point," she said. "A warmer climate becomes a bad thing instead of a good thing."

Read the Climate Central story - “North American Forests Not a Climate Change Remedy.”