NASA, 2007: 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.

Wikipedia: Hurricane Katrina was the eleventh named storm and fifth hurricane of the 2005 Atlantic hurricane season. It was the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States.

“Nobody expected 80 percent of the city to be under water.”

Timeline of Katrina events (National Geographic)

Related
Hurricane Katrina https://en.wikipedia.org/wiki/Hurricane_Katrina
Hurricane Katrina Day by Day https://www.youtube.com/watch?v=HbJaMWw4-2Q
What Are The Chances Of Another Katrina? https://www.youtube.com/watch?v=jt0n_7TZamE
Forests Damaged by Hurricane Katrina Become Major Carbon Source http://www.nasa.gov/mission_pages/hurricanes/archives/2007/katrina_carbon.html
Hurricane Season 2005: Katrina http://www.nasa-usa.de/vision/earth/lookingatearth/h2005_katrina.html
New Orleans and Gulf Coast Flooding in the Aftermath of Katrina http://www.nasa-usa.de/vision/earth/lookingatearth/gulfcoast_flood.html
Katrina Retrospective: 5 Years Later http://www.nasa-usa.de/mission_pages/hurricanes/features/katrina-retrospective.html
Dr. Jeff Masters’ WunderBlog Archive from August 2005 http://www.wunderground.com/blog/JeffMasters/archive.html?year=2005&month=08
Major Hurricane Katrina Archive Data http://www.wunderground.com/hurricane/atlantic/2005/Major-Hurricane-Katrina