With the help of NASA satellite data, a research team has estimated that Hurricane Katrina killed or severely damaged 320 million large trees in Gulf Coast forests, which weakened the role the forests play in storing carbon from the atmosphere. The damage has led to these forests releasing large quantities of carbon dioxide into the atmosphere.

The August 2005 hurricane affected five million acres of forest across Mississippi, Louisiana and Alabama, with damage ranging from downed trees, snapped trunks and broken limbs to stripped leaves.

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. An event that 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 team’s findings were published Nov. 15 in the journal Science.