More storms now than ever? Yes. No. Maybe.

Nov 16, 2010

The following article was published in the Sarasota Herald-Tribune on November 14, 2010: 

 More storms now than ever? Yes. No. Maybe.

By Paige St. John

The common insurance industry claim that hurricanes are on the rise lacks an essential ingredient — scientific agreement.

Findings that show a rise in hurricane activity over the Atlantic Ocean have been challenged by new studies. Some scientists say what has actually increased is the ability to spot storms. Others point out that what matters most has not changed at all — the number of storms coming ashore.

There is no single, shared scientific view that hurricanes are more frequent or more dangerous, according to Colorado State University science policy professor Roger Pielke Jr.

“There are instead many scientific justifications pointing in different directions.”

Faced with a choice, insurers understandably tend to favor that which leads to the highest rates, and thus the best chance they can cover anything.

That’s good for insurers, but not necessarily for their customers.

Insurers have embraced the work of researchers such as Massachusetts Institute of Technology climatologist Kerry Emanuel, who in 2005 concluded that rising ocean temperatures had nearly doubled the destructive potential of hurricanes.

Such findings were the most-cited reason for huge spikes in coastal insurance premiums over the past five years.

But in a recently published scientific paper, even Emanuel concedes some of his original conclusions may have been premature.

All along, there have been scientists with a different view.

To start, there is no increase in hurricane activity where it tends to matter most — on land. And the increase in storms at sea may have more to do with tracking methods than an actual increase in storms.

Older hurricane counts relied on storms being encountered by passing ships. Shipping routes left a huge “hole” in the Atlantic with little traffic, and thus little record of storm activity.

Only since the advent of satellites have scientists been able to see every storm, no matter how remote or short-lived.

Tropical disturbances are now measured hourly, increasing the chance of capturing peak intensity. And what it takes to be declared a storm has been relaxed to include even so-called “mini-whirls” that blow up and die in a day.

Six of the storms in 2007 and 2008 were so weak and short-lived they likely would have remained nameless in past years, said Chris Landsea, science and operations officer at the National Hurricane Center.

Adjusting for these changes, Landsea concludes that Atlantic hurricane activity shows a slight decline.

Other scientists contend that for the past 30 years at least, hurricane activity in the open Atlantic has increased.

The question for them is why there is no noted increase on land.

Some scientists say conditions warming up the Atlantic also promote wind sheer that kills hurricanes.

Others say the year-to-year unpredictability of hurricanes is so great it drowns out any small changes in the average number of storms.

Florida State University researcher Jim Elsner says common sense dictates that a rise in ocean activity will, sooner or later, mean an increase on shore.

“This climate signal is less clear,” hedged Tom Knutson, a hurricane researcher at the National Oceanic and Atmospheric Administration.

The odds slightly favor Elsner’s point of view, Knutson said, but “there is no certain answer.”

The common insurance industry claim that hurricanes are on the rise lacks an essential ingredient — scientific agreement.        

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