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Earth Sense: Hurricanes impact is usually unpredictable
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Hurricane season starts a few weeks from now. With all the news about climatic change, it raises the question whether we’ll have more hurricanes than ever. Will they be more powerful? And most importantly, which land areas will they invade?

The National Oceanic and Atmospheric Administration uses a measure called ACE, or Accumulated Cyclone Energy Index.  It calculates the total wind power unleashed by the hurricanes of a given season.

But there’s no surefire way to predict what’s going to happen this summer. Even if current speculations about another El Niño year with increased storm activity become reality, we still don’t know where the trouble is going to hit.

A massive event like Katrina in 2005 can bring disaster to New Orleans and even affect Georgia, as we’ve seen with the tornado in Helen. But it will make little difference in Massachusetts. On the other hand, a hurricane can graze the entire eastern shore to Canada, without bringing rain to Hall County.

To illustrate the complexity of the topic, I had my students in China examine U.S. hurricane data for the past 150 years. A simple statistical test (called “Fisher’s F”) indicates whether there is a significant difference between groups of years.

A first result was that the years 1852 to 1950 showed as many hurricanes as the decades from there to the present. When we sharpened the view and looked at a 30-year period from the 1980s to now, compared with the previous 30 years, the difference became significant.

More storms occurred recently than did 60 years ago. Katrina was among the recent ones, along with monsters like Wilma, clobbering Florida just two months after Katrina. Ivan visited our state in 2004, causing fatalities in Cleveland and elsewhere.

The group of years also included Gilbert (1988), Hugo (1989) and “Superstorm Sandy” (2012). But in spite of the deaths and destruction wreaked by those storms, the ACE index showed that there was no significant “energy” difference between the recent 30-year period and the earlier one.

A simple classroom exercise like that doesn’t provide a climatic model and won’t predict the future. But it shows how complicated the factors are. In the absence of a way to reliably predict when and where the next hurricane will hit, the safest way to avoid trouble is not to build directly on the Atlantic waterfront.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.

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