Carbon Storage in Temperate Forests Could Drop Sharply as the World Warms

A new study of the Sierra Nevada Mountains in the western U.S. shows that forests there are likely to store dramatically lower amounts of carbon as temperatures increase.

California's southern Sierra Nevada mountains. 

California's southern Sierra Nevada mountains.  FOTOLIA

Researchers from several U.S. universities said that the mean amount of carbon stored by trees in the Sierra Nevada is expected to fall by an amount equal to 73 percent of the total above-ground stock of carbon currently stored in all California vegetation.

Writing in the journal Scientific Reports, the scientists said that the reason for the steep decline in carbon storage is two-fold. The first is that as temperatures rise and the Sierra Nevada experience drier conditions, some tree species will grow more slowly, thus storing less carbon. The second reason is a projected increase in forest fires because of warmer, drier conditions; the fires not only release large amounts of carbon but also reduce the number of trees taking up CO2 from the atmosphere. Similar effects could be felt in other temperate forests worldwide.

The scientists based their conclusions on studies of how various tree species react to increased warmth and reduced moisture, and also on climate projections developed by the Intergovernmental Panel on Climate Change. One solution to the projected loss of carbon storage, the paper said, would be to regularly thin forests so that when fires break out they are not as severe as blazes that sweep through forests that have not been thinned or cut.