Hurricane activity at all-time high

Hurricane Wilma, a Category 3 storm, made landfall in Florida Monday. Wilma weakened to a Category 2 storm as it traveled across land from Miami to Fort Lauderdale and West Palm Beach on the Atlantic coast. The storm killed at least six people in Florida and killed 19 people when it traveled through the tropics this past week.

Wilma is the 21st named hurricane of the 2005 hurricane season, making this season the most active season since 1933. Wilma is also the last of this year's named hurricanes, with the recent 22nd hurricane named for the Greek letter alpha.

Benjamin Giese, an oceanographer at Texas A&M, said hurricane activity is modulated by changes in the ocean, but that there is no single factor that is causing the increase in hurricanes this season.

"There is a current discussion about global warming causing (the hurricanes), but this is only an unproven hypothesis," Giese said. "The main factors affecting this season are most likely El Niño and decade-to-decade ocean changing."

Giese said the oceans change much more slowly than the atmosphere and that the climate of the ocean should not be significantly different next year.

James Hurrell, director of climate and global dynamics division at the National Center for Atmospheric Research (NCAR), said it is not responsible to assume that humans have had no affect on the increase of hurricanes this season.

"We know that we have altered the chemical composition of the atmosphere," Hurrell said. "We've seen rapid increases in greenhouse gases over the past century due to human activities."

Hurrell, who is also a senior scientist at the NCAR, located in Boulder, Colo., said the increase in greenhouse gases raises the temperature of the atmosphere, which in turn increases the rate of evaporation. He said that when there is more water in the air there is a greater increase in the severity of storms.

"Along with the increase in atmospheric moisture the global sea levels have also risen, which causes greater storm surges," Hurrell said.

Hurrell said that to help decrease the amount of greenhouse gases in the atmosphere, changes need to be made individually and internationally.

"We should seriously be looking at an alternative fuel source," Hurrell said. "We have to cut back on the burning of fossil fuels and other sources of greenhouse gas."

Hurrell said the climate is in a warm phase of tropical temperatures, and that an active hurricane season can be expected next year.

Brent McRoberts, a graduate student who studies climate, said La Niña, which is a phenomenon that creates cooler sea surface temperatures in the eastern Atlantic Ocean, creates favorable conditions for hurricanes to form in the Atlantic Ocean.

McRoberts said winds in the atmosphere have been very weak, which also helps hurricanes to develop. He said tropical storms are usually torn apart by wind before developing into hurricanes.

"Global warming is a much too gradual process to cause the increase in hurricanes this season," he said.

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