Subscribe to our free daily newsletters
. Earth Science News .

Subscribe to our free daily newsletters

Warmer seas boosted hurricane frequency by 40 percent: study

by Staff Writers
Paris (AFP) Jan 30, 2008
Warmer seas accounted for 40 percent of a dramatic surge in hurricanes from the mid-1990s, according to a study released on Thursday by the British journal Nature.

The paper -- the first to calculate the precise contribution of sea temperatures in driving hurricane frequency -- could be a major contribution to scientists struggling to understand impacts from global warming, its authors say.

Hurricanes -- the term for fierce cyclones that brew in the Atlantic and threaten Central America, the Caribbean and southern United States -- are known to have several causes.

One of them is the raw fuel of heat and moisture, provided by seas warmed to at least 27 degrees Celsius (80.6 degrees Fahrenheit).

Another, called vertical wind shear, is the angle of prevailing winds. These dictate whether the infant storm will develop into the wheeling shape of a hurricane or instead be torn to be pieces.

British researchers Mark Saunders and Adam Lea of the Benfield UCL Hazard Research Centre at University College London, looked at yearly US meteorological data for hurricanes between 1965 and 2005 and compared these to a 50-year average.

Over the half century, there were around six hurricanes per year on average, roughly half of which were intense hurricanes.

But for the 10 years from 1996 to 2005, the tally rose to about eight hurricanes per year, about four of which were intense ones.

Hurricanes that made landfall in the United States also became more frequent -- one extra storm every three years or so, statistically speaking.

After stripping out the role of wind in hurricane generation, the researchers calculate that an increase of 0.5 degrees Celsius (0.9 Fahrenheit) was responsible for about 40 percent of the rise in hurricane activity.

Saunders told AFP the findings could be a big help for computer modellers striving to understand whether global warming will stoke hurricanes, a scenario that has been sketched by many experts but remains hedged with many unknowns.

But he cautioned against the temptation to extrapolate that hurricane activity will triple or quadruple if the IPCC's predictions of a global temperature rise to 2100 come true.

"Extrapolation assumes that the vertical wind shear will remain constant, whereas some models suggest that it will go up. This would mean that vertical wind shear would have a suppressing effect, counterbalancing the enhancing effect from higher temperatures," he explained.

Nor is it a given, said Saunders, that in the future a sharp rise in sea temperatures will generate so much hurricane fuel, as happened from the mid-90s.

"It could be that currently we are close to the (temperature) threshold for hurricane generation," said Saunders. "It could be that as the sea waters warm more, maybe the sensitivity to sea warming might decrease. Scientists just don't know the answer to this one way, or another."

Oceanographers sometimes have "very fierce and quite acrimonious debates" about the impact of global warming on hurricanes, said Saunders.

Some say the surge in hurricanes at the end of the last century can clearly be pinned on warmer seas.

Others say it is wrong or premature to blame human interference with the climate system. They say there are natural cycles of hurricanes and reliable data -- usually accepted as the advent of weather satellites in the 1960s -- is far too recent to take this into account.

Last year, the UN's Intergovernmental Panel on Climate Change (IPCCC) said it was "likely" that tropical cyclones will become more intense this century. The storms could pack higher peak winds and heavier rainfall as tropical seas warmed.

The 1996-2005 decade climaxed with Hurricane Katrina, the most devastating storm ever to whack the United States.

But 2006 was quieter, and 2007 was unusually calm. Last year, sea temperatures in the tropical Atlantic were even slightly below the norm.

Email This Article
Comment On This Article

Related Links
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Tropical cyclone batters Fiji
Suva (AFP) Jan 29, 2008
A tropical cyclone battered the South Pacific island nation of Fiji, causing widespread flooding, blackouts in the capital and at least three deaths, officials and reports said Tuesday.

  • Migrant workers sleeping rough in China's big freeze
  • China sends in army to battle snow chaos
  • Malawi's flood disaster set to get worse: govt official
  • Making (Accurate Predictions Of) Waves

  • Microbes As Climate Engineers
  • When Accounting For The Global Nitrogen Budget Do Not Forget Fish
  • Economists Help Climate Scientists To Improve Global Warming Forecasts
  • US pushes its climate change agenda despite criticism

  • Russia To Launch Space Project To Monitor The Arctic In 2010
  • New Radar Satellite Technique Sheds Light On Ocean Current Dynamics
  • SPACEHAB Subsidiary Wins NASA Orbiting Carbon Observatory Contract
  • Radical New Lab Fights Disease Using Satellites

  • Nuclear, solar and geothermal energy pushed at Philippine summit
  • Outside View: Oil firms boom on Iraq war
  • Analysis: Venezuela expands influence
  • Bacteria might be used to make natural gas

  • Analysis: NATO begins pandemic monitoring
  • China reports outbreak of bird flu in Tibet
  • Rains offer hope for bird virus outbreak
  • Epidemic superbug strains evolved from one bacterium: study

  • Rare dolphin 'beaten to death' in Bangladesh
  • Cold Spring Harbor Laboratory Researchers Race Against Time To Save Tasmanian Devils
  • Telepathic Genes
  • Nonlinear Ecosystem Response Points To Environmental Solutions

  • Protecting The Alps From Traffic Noise And Air Pollution
  • EU threatens Italy with court action over rubbish crisis
  • In Cairo the noise pollution can be a killer
  • One dead, hundreds sick after China chemical leak: hospitals

  • Brain Connections Strengthen During Waking Hours And Weaken During Sleep
  • Higher China fines for stars breaking one-child rule: state media
  • Fueling And Feeding Bigfoot
  • English to be the world's 'language of choice': British PM

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2007 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement