Washington, Nov 16: A new research suggests that the forests damaged by Hurricane Katrina in 2005 led to the release of a large amount of carbon dioxide in the atmosphere, thus contributing to global warming.

Using data from a NASA satellite, the research team estimated that the 320 million trees in Gulf Coast forests were damaged by the 2005 Hurricane, leading to the weakening role of the forests in storing carbon from the atmosphere.

The field samples and satellite images, along with results from computer models that simulate the kind of vegetation and other traits that make up the forests, were used to measure the total tree loss the hurricane inflicted. The scientists then calculated total carbon losses to be equivalent to 60-100 percent of the net annual carbon sink in U. S. forest trees.

"It is surprising to learn that one extreme event can release nearly as much carbon to the atmosphere as all US forests can store in an average year, " said Diane Wickland, manager of the Terrestrial Ecology Program at NASA Headquarters in Washington. "Satellite data enabled the research team to pin down the extent of tree damage so that we now know how these kinds of severe storms affect the carbon cycle and our atmosphere, " he added.

Young growing forests play a vital role in removing carbon dioxide, a greenhouse gas, from the atmosphere by photosynthesis, and are thus important in slowing a warming climate.

But an event like Katrina, which kills a great number of trees, can temporarily reduce photosynthesis, the process by which carbon is stored in plants. More importantly, all the dead wood will be consumed by decomposers, resulting in a large carbon dioxide release to the atmosphere as the ecosystem exhales it as forest waste product.

"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, " said the study's lead author Jeffrey Chambers, a biologist at Tulane University in New Orleans, La. "If, as many believe, a warming climate causes a rise in the intensity of extreme events like Hurricane Katrina, we're likely to see an increase in tree mortality, resulting in an elevated release of carbon by impacted forest ecosystems, " he added.

Young forests are also valued as carbon sinks, which remove carbon dioxide from the atmosphere and store it in growing vegetation and soils. In the aftermath of a storm as intense as Katrina, vegetation killed by the storm decomposes over time, reversing the carbon storage process, making the forest a carbon source.

"The carbon cycle is intimately linked to just about everything we do, from energy use to food and timber production and consumption, " said Chambers. "As more and more carbon is released to the atmosphere by human activities, the climate warms, triggering an intensification of the global water cycle that produces more powerful storms, leading to destruction of more trees, which then act to amplify climate warming, " he added.

The research team's findings were published in a recent issue of the journal Science. (ANI)