Scientists from Tulane University and the University of New Hampshire have concluded that the severe damage Hurricane Katrina inflicted on five million acres of forest has led to a large release of carbon dioxide into the atmosphere.

As many as 320 million large trees were killed or severely banged up in Gulf Coast forests. When healthy, these trees act as carbon sinks, pulling the stuff out of the air. Without them around, that carbon dioxide is free to travel up into the atmosphere. On top of that, the decomposition process releases still more carbon dioxide.

Lead author Jeffrey Chambers, a biologist at Tulane, had this to say: "The loss of so many trees will cause these forests to be a net source of carbon dioxide to the atmosphere for years to come." The work is in the latest issue of Science.—Gregory Mone