Hurricane Katrina was formed during the 2005 Atlantic Hurricane season and caused devastation along the Gulf Coast region where it made landfall.  At least 1,836 people lost their lives during the storm, which also caused over $81.2 billion US dollars in damage. After the hurricane, many theorized that global warming was a key factor in creating stronger hurricanes and, therefore, was the cause of much of the destruction Katrina caused. 

A recent study released by a prominent federal scientist, Tom Knutson, claims this is not so. In addition, the study done by the meteorologist finds that the increase in ocean temperatures will actually reduce the number of hurricanes in the Atlantic, as well as those strong enough to make landfall. The results of this study contradict prior studies done by Mr. Knutson, but seem to confirm the results of a study (pdf) published in January by Chunzai Wang, a research oceanographer at NOAA, the National Oceanic and Atmospheric Administration based in the United States.

Research in this study concluded that warming waters in the Indian and Pacific oceans causes increased vertical wind shear in the Atlantic Ocean near the United States. Wind shear is a change in wind speed or direction and makes it difficult for hurricanes to form, strengthen, and continue. According to the study, for every degree the ocean warms, wind shear increases by up to 10 MPH, weakening hurricane storm formation.

The study finds that due to the increase in water temperature from global warming trends and related wind factors, hurricane formation should drop by 18 percent by the end of the century, and the number of hurricanes making landfall in the United States will drop by 30 percent. Not all of the research results paint an encouraging picture; although the number of storms will decrease the study also predicts that rainfall and wind strength during hurricanes should increase.

Knutson's study is the latest addition in the ongoing contentious scientific debate on the effects of global warming upon the frequency and severity of hurricanes. Already, the results of the study have drawn criticism as well as praise from different scientists around the United States.

On the other side of the argument, a recent study by J. Andrew Hoerner and Nia Robinson, "A Climate of Change" (pdf) funded in part by the Ford Foundation, quotes IPCC findings (pdf) and a recent MIT study (pdf):

The Intergovernmental Panel on Climate Change recently found that "there is evidence for an increase in the average intensity of tropical cyclones in most basins of tropical cyclone formation since 1970 as well as in both the number and intensity of storms in the Atlantic." This conclusion is reinforced by a recent study by MIT's Kerry Emanuel, finding that in the last 30 years, the destructive power of hurricanes has increased 70 percent in both the Atlantic and Pacific oceans. A more recent study by Emanuel, using a theoretical model rather than historical review, found that future North Atlantic hurricanes are likely to be more intense as a result of global warming.

But the results of these studies may be of little consequence to residents of hurricane prone areas as they deal with hurricane season, which started June 1^st and continues until November 30^th. Even if the number of storms will decrease due to warming trends, it only takes one storm - like Hurricane Katrina - to create widespread destruction of property and loss of life. The documentary Trouble the Water, which will be released on August 22^nd in New York and Los Angeles, looks at the ongoing devastation of such a disaster. The key is to be prepared for hurricane season, no matter how many hurricanes may or may not be formed.

Further Reading:

• The High Cost of Doing Nothing on Climate Change
• The Chance to Transform: Eco-Cities and Sustainable Housing After Storms
• Hurricanes - Enough Already
• Hurricane Katrina - Where Are We Two Years On?