Is Global Warming Causing More Devastating Hurricanes Worldwide?

Hurricane Katrina was downgraded from a level five to a level four storm just before it made landfall in Louisiana this morning. The storm is judged by weather experts to have the strongest central force, or intensity, of any recorded storm in the United States except the Labor Day Hurricane of 1935. Torrential rains are inundating the coast and winds around 250 kilometers per hour are ripping through New Orleans. The massive storm prompted an unprecedented evacuation of the city.

* Ray Nagin, Mayor of New Orleans

The city of New Orleans is below sea level and faces major flooding from Hurricane Katrina. More than half a million people have been ordered to evacuate the city and the storm could leave up to one million people homeless.

President Bush declared a state of emergency for Louisiana and Mississippi over the weekend. Federal emergency workers are preparing staging centers to deal with the fallout of the storm.

As Katrina pounds New Orleans, we are going to look at how this storm compares to others that have hit the United States and at the link between climate change and hurricane strength.

Tropical storms may be growing in overall intensity due to human-induced global warming, according to a new study by leading hurricane researcher Kerry Emanuel. His report, which has generated controversy among climate specialists, was published earlier this month in the journal Nature. Emanuel looked comprehensively at storm data since the mid-1970s and concluded that the destructive power of hurricanes has nearly doubled over the past three decades at least partially because of human-induced global warming. Critics of the study say hurricanes are not intensifying and that the cause of the rising ocean temperature is natural, not human-made.