Hurricane experts are predicting a potentially devastating hurricane season this year. With more tropical storms expected to head our way, the odds of a major storm making landfall in a populated area are also on the rise.

But that may not even be the bad news. Scientists unearthing prehistoric hurricane patterns warn that we’ve actually been in a hurricane lull, and that lull is due to come to an end.

Living with the likes of Andrew

Andrew, which devastated southern Florida in 1992, was far and away the costliest hurricane in history, causing nearly $27 billion in damage. (However, it didn’t make the 30 deadliest hurricanes list.) Now, rather than a rarity, scientists warn that catastrophic storms like Andrew are about to become much more commonplace.

"The probability that we’re going to see a major hurricane hit one of our major cities has increased," says James Elsner of Florida State University. "It looks like it’s going to be above what it’s been for the last 30 years."

Elsner has long used historical records to study patterns of hurricane activity. But those records only go back a couple of centuries. So recently Elsner and others began digging up the geological record.

Tracing tempests

Elsner bases his prediction on the impact storms have on coastal geology. A major hurricane like Andrew blows a wall of seawater onto land. The same storm surge that washes away lives and property also leaves behind a sandy footprint.

"We look at what are called paleotempestology data which are records of overwash deposits on the coast line," Elsner says. "These deposits sit in the bottom of the lakes, and if you core in those lakes you can see sand layers indicative of hurricane activity in the past."

Elsner and colleague Kam-biu Liu of Louisiana State University have analyzed lake core sediments from both the Atlantic and Gulf coasts.

While those who endured hurricanes like Hazel in 1954 or Camille which struck in 1969 may disagree, Elsner and Liu’s results show that we’ve actually been in a cycle of low hurricane activity for hundreds of years, a period that’s coincided with the development of America’s coastlines.

Scary Shifts

Elsner hopes both insurance companies and community planners will heed his predictions. "I think that its necessary to pay attention to the kind of climate fluctuations that are possible," he says. "We tend to focus on a very narrow time scale when we think of development, but the climate responds much more slowly. When we see these shifts, it scares us.

"And if you start to think in terms of two or three Andrews per year along the southeast coast line, most people don’t think that that’s even possible."

Elsner and Liu say not only will we have more storms, but odds are they’ll be bigger storms. The complete results of their study will be published July 1st in the Journal of Climate.

The storm surge story

Elsner says insurance companies are most interested in wind damage. "But that’s only half the story," he points out. "Most deaths from hurricanes in the United States are from the storm surge."

And, Elsner warns, scientists still can’t predict what type of damage to expect, or where, resulting in surprises like the flooding from Floyd. While Andrew hit land with category four force, it produced very little precipitation. Floyd, a relatively weak storm, put much of North Carolina under water.

"We need to focus a little bit more on trying to understand the mechanisms and the predictability of rainfall from these storms when they make landfall," Elsner says. "I think that’s one of the key scientific issues of the 21^st century."

Elsewhere on the web:

The 30 Costliest U.S. Hurricanes

The 30 Deadliest U.S. Hurricanes

Hurricane Categories—the Saffir-Simpson Scale

"Hunting Prehistoric Hurricanes"

What to Do When a Hurricane Watch/Warning is Declared

NOAA Photo Page—Hurricanes