Following last year's hurricane season, the most active in US history, scientific debate has intensified as US scientists seek to prove or dispute the theory that human-caused global warming and the greenhouse gas effect are unleashing more threatening natural disasters.
Despite their differences over the cause of the intense storms, most observers agree that the migration of people to the coasts and the destruction of natural landscapes by development in coastal cities has created an increasingly lethal situation.
There's also little doubt that warmer water in the Atlantic plays a role. The hotter that body of water and the air over it, the worse and more frequent the storms, which draw upon the heat energy for increasing strength, scientists say.
But in a chicken and egg type debate, they differ over what's causing the increasing temperatures -- global warming that comes from behavior, or warming that is part of a natural cycle. Others cite changes in the way the intensity of hurricanes is measured and have questioned whether the storms are even generally stronger than they were years ago.
In the most recent studies that blame human influence for the warming, a chorus of scientists points to the connection between warming waters and more intense storms.
A new study by James Elsner, a Florida State University geography professor, in the journal Geophysical Research Letter, seeks to show that the air temperatures in the Atlantic Ocean influence the ocean's surface temperatures, not vice versa. Elsner's data lends more support to the idea that it is changes in the atmosphere that have created more and stronger storms.
Another climate researcher, Judith Curry, put forward the thesis in her research that increasingly high water temperatures have led to increasingly strong hurricanes. Kerry Emmanuel, a professor at the Massachusetts Institute of Technology, argues that his work found such a strong link between higher water temperatures and the intensity of hurricanes that the connection cannot be an accident.
In a report about climate change, researchers from the National Academy of Sciences state that greenhouse gases are at their highest level in 400,000 years. They write that extreme weather, such as Hurricane Katrina, "may indicate a contribution from climate change, and the likelihood [that] extreme events could increase in the future."
One of the strongest opponents of this view is Christopher Landsea of the National Oceanic and Atmospheric Administration's Hurricane Research Division in Miami, Florida. When US President George W Bush visited the center at the end of last month, Landsea said there is no consensus that stronger storms are a result of global warming.
Landsea wrote in a recent issue of the journal Science that poor measurements based on less sophisticated technology could have resulted in inaccurate classification of hurricanes in previous decades. Hurricanes that were category three would now be classified in a higher category.
Landsea and his supporters argue that natural causes lead to an especially active hurricane season every ten to 40 years followed by a less active season. This year's hurricane season, which began on June 1, has been much quieter than predicted, showing how varied weather can be.
Frank Lapore of the National Hurricane Center, says there are a variety of reasons why hurricanes have killed so many people and caused so much damage in the last several years. He attributes much of the damage to the migration of more people to the coasts during the 1970s and 1980s. Since 1995, more storms have been hitting the increasingly denser coastal population centers.