Hurricane Planet: Is the Worst Yet to Come?

Discovery.com, Aug. 23, 2007-08-23

Aug. 22, 2007  If Earth is running a fever, then hurricanes like Dean and Katrina are her febrile seizures. As the rise in global temperature has accelerated over the last century, these tempestuous spasms have become more frequent and violent.

Each new spinning storm is also finding ever more victims populating its coastal targets  whether it be Mississippi or Madagascar, Kingston or Connecticut  and more ways to trigger trouble thousands of miles inland by way of an ever-more interdependent, globalized economy.

Climatologists and hurricane scientists now have little doubt there is a connection between hurricanes and global warming. Some of the strongest evidence comes from 100 years of records on Atlantic hurricanes  the most complete archive of its kind for any ocean basin. That record shows hurricanes have been increasing in a stepwise fashion since 1900.

Today, the average number of hurricanes each year is double that of the first decade of the 20th century. What's more, the intensity of the storms is increasing even faster than the numbers.

"If you take the last 10 years, we've had twice the number of category-5 hurricanes than any other (10-year period) on record," said Greg Holland of the National Center for Atmospheric Research.

He and Peter Webster of Georgia Tech are the authors of a July 30 study showing the stepwise increases in hurricanes.

It's no coincidence that the same 10 years have seen seven of the warmest years on record, including 2007, which some climate scientists in the United Kingdom and the United States are already predicting will be the warmest ever.

Today there are an average of two category-5 hurricanes each year, Holland told Discovery News. And there's no reason to believe similar increases aren't being seen worldwide, he said.

Madagascar, for example, is getting hit almost annually by monster storms. Even the usually quiet Arabian Sea was hit by a category-5 storm this year: Typhoon Gonu, which threatened major oil production facilities, on which the global economy depends.

Global Warming's Wrecking Ball

Strange as it sounds, all hurricanes are born with a benign purpose. They are, in the simplest terms, one of the ways Earth continuously tries to even out the temperature differences between the tropics and the poles.

The storms begin close to the equator and trek to higher latitudes, carrying heat and energy from the ocean and atmosphere to cooler climates. "They also stir up the oceans," said Holland. "That enhances the pole-ward transfer of heat."

So it stands to reason that if greenhouse gases are causing more solar energy to build up in the oceans and air, the same method of transferring heat toward the poles ought to rev up as well. Voila: more numerous and powerful hurricanes. It all makes sense, although getting at the details of this relationship is one thing keeping climatologists busy right now.

"Any one hurricane you cannot say a whole lot about," said Holland. "You can't say that Katrina was caused by global warming, but you can say global warming will cause more Katrinas."

Among the complicating factors, for instance, is how global warming affects the strength of winds aloft, which can shear the tops off of storm clouds and stunt the growth of hurricanes. The El Nino condition in the Pacific Ocean is one factor which can increase "wind shear" over the Atlantic, thereby limiting hurricanes  even as other forces may be strengthening them.

Hurricane Economics

Regardless of the cause, the hard fact that there are more Katrinas and Deans on the way raises a frightening question: How many of these city-wrecking, murderous storms can we take?

"The U.S. can afford it," said Holland. But he points out that "afford" is a tricky word. "For every billon we spend on levees, that's less for bridges in Michigan."

Other economic effects are often overlooked when calculating the cost of a hurricane. Some estimates of Katrina's effect on the price of oil, and therefore transportation, put it at $20 to $30 billion extra shelled out by U.S. consumers in that storm's aftermath.

An indirect hurricane effect on the United States  and other developed nations  is the mass movement of people internally and across borders when a storm wipes out a local economy. Take the case of Jamaica, for instance, if Hurricane Dean had hit the island nation head-on.

"If you're a country like Jamaica you can't afford it," said Holland. The damage can be greater than the country's entire gross domestic product and set the nation back decades in development, he said.

Coasting to Trouble

The danger of such regional troubles is increasing in the United States as the population rises and more people move to the coasts, added David Kelly, an associate professor of economics at the University of Miami.

"For a lot of reasons, the population density along the coasts is increasing," said Kelly. Unfortunately, that doesn't mean housing and other buildings are being built with any more awareness of hurricanes. The result is that even before factoring in more hurricanes and rising sea levels, there's a growing probability of trouble on the coasts.

"There are more (hurricane) targets," said Kelly. "Many, many more targets."

Normally, people would adapt to the threat of hurricanes by building stronger structures, Kelly said. But that's not happening in Florida.

"When places like Florida put a (state-mandated) cap in insurance rates, no one is going to do that," Kelly said. There is no incentive to build a hurricane-proof house if there's no immediate financial benefit from doing so. Other U.S. urban areas which are facing a growing hurricane threat include Long Island, Tampa, Galveston, Wilmington and New York.

So will people do what's necessary to prevent Katrina-like disasters in the future? Maybe not. In the end, it comes down to human nature, said Kelly.

"People have a really hard time with very low-probability, high-impact events," said Kelly. Perhaps we'll do better in the future, but if the history of past disasters is any hint, humanity has a poor track record in planning for such troubles.

Source: Discovery News

Copyright © 2007 Discovery Communications

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