Worst Forest Disaster in U.S. History

Nov. 16, 2007— -- When Hurricane Katrina slammed into the Gulf Coast two years ago, the storm devastated 320 million trees.

Now the United States is suffering the worst forest catastrophe in its history, according to a new analysis by the journal Science.

Using satellite images, scientists found that more than 5 million acres of trees were destroyed across Mississippi and Alabama. Experts said it would take decades for the plant life to recover, and some areas may be permanently damaged.

"An area of the state of Maine was affected, and that's a huge area," said George Hurt, an ecologist who was also a co-author the Science study. "More than 10 times the size, for example, of what was affected by the California wildfires recently. So this is a huge event."

But of even more concern is that these fallen forests will have soon released as much carbon dioxide back into the air -- 367 million tons of it -- as all the rest of U.S. forests absorb in an entire year. Trees capture carbon dioxide, which they turn into oxygen and use to create wood and leaves. As this fallen lumber starts to decay, they release these greenhouse gases into the air, which in turn hastens climate change.

"It is an irony that the change we may see as the climate warms, with increased storms of this magnitude, could be accelerating the source of the emissions that create the change, so the change could be accelerating itself," said Glenn Prickett, a forestry expert for Conservation International.

Deforestation already accounts for nearly one in every five tons of carbon dioxide that humanity worldwide puts into the atmosphere. And Katrina's wake has now added to this deforestation. Such hurricanes become more likely, say many scientists, as global warming accelerates due to greenhouse gas emissions. Scientists call this phenomenon a feedback loop; the warmer it gets, the more likely that storms could kill more forests, which would release even more greenhouse gas.

"A major source of greenhouse gases that are contributing to climate change is actually the loss of forests," Prickett said.