Atlantic cyclones may decrease as globe warms: study

By Jim Loney

MIAMI (Reuters) - Fewer but more intense hurricanes may form in the Atlantic Ocean as the globe warms toward the end of this century, according to a new study that counters predictions of more frequent cyclones due to climate change.

The study, published on Sunday in Nature Geoscience, adds fuel to a fierce scientific debate over whether human-produced greenhouse gases have contributed to a recent rise in hurricane activity in the Atlantic basin and whether tropical cyclones are becoming stronger.

A simulation of Atlantic hurricane activity for the final decades of the century projected an 18 percent decrease in hurricanes and a 27 percent decrease in tropical storms, researchers at the U.S. government's Geophysical Fluid Dynamics Laboratory in New Jersey found.

"It does not support the notion that increasing greenhouse gases are causing a large increase in Atlantic hurricane or tropical storm frequency," said Thomas Knutson, one of the study's authors.

Recent studies have found links between rising sea surface temperatures in the tropical Atlantic Ocean, where cyclones form, and some measures of hurricane activity. Tropical storms and hurricanes draw their energy from warm sea water.

Around 1995, scientists believe, the Atlantic entered a period of higher hurricane activity that could last 25 to 40 years. Some researchers attribute the rise to natural cycles, while others believe global warming may be brewing more, and more intense, storms.

The frenzied hurricane seasons of 2004, when four strong hurricanes hit Florida, and 2005, when a record-breaking 28 storms formed, fired up the climate change debate.

The next six-month Atlantic hurricane season begins on June 1 and forecasters expect it to be a busy one, well above the long-term average season that produces about 10 tropical storms and six hurricanes.