12 January 2009

Hotter world cooks up storms

Hurricanes like Katrina may be followed by even fiercer storms if we don’t put the brakes on human-induced global warming.

Research by a top meterologist suggests that global warming, the rise in the earth's temperature due to our ongoing use of fossil fuels, may be contributing to increasingly vicious hurricanes – with worse to come in future.

Hotter seas are storm 'engine'
Raised sea temperature in the tropics is the ‘engine’ for hurricane genesis, so for years scientists have speculated that increased global temperatures could fuel more and worse storms. This has always been hotly debated and studies weren’t able to provide convincing evidence to persuade those who scoffed at the theory.

But a 2005 study published in the journal Nature by Professor Kerry Emanuel, an eminent meteorologist at the Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, states that tropical cyclones (hurricanes and typhoons) have indeed worsened - a trend shown to correlate with higher sea surface temperatures.

Hurricane power up by 50%
Previous studies have tried to gauge whether hurricanes were becoming more frequent: the general consensus has been that this was not the case. Emanuel's research, however, focused on the total energy generated by a storm during its 'life span'.

He examined global hurricane records from over the last thirty-odd years, and found that although the frequency of these storms has not increased in any significant way, there is a distinct upward trend overall in intensity


Emanuel found that the amount of energy released in hurricanes in the North Atlantic and the North Pacific oceans has increased markedly over the last 30-50 years: both the duration of the storms and the wind speeds they produce have increased by about 50 percent.

Link with global warming
Increases in the average surface temperature of the tropical ocean over more or less the same time period suggests that this warming is a key factor responsible for the more potent hurricanes. Most scientists now agree that the rise in sea surface temperature is due to global warming.

If global temperatures continue to rise, hurricane activity could increase, given that there is more heat to drive the tropical cyclone process. And more powerful storms mean more loss of life, and more damage to economies, especially given that coastal populations – those hit hardest by such storms – are growing in many parts of the world.

(Olivia Rose-Innes, Health24)

Emanuel, K. A., 2005: Increasing destructiveness of tropical cyclones over the past 30 years. Nature, 486.

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