Watching the water 



BY NANCY DAVIS 



Sea level has been rising for the 

 past 17,000 to 18,000 years. It's part of 

 a natural trend. 



So what's new? 



Plenty, says Stan Riggs, a geologist 

 at East Carolina University. 



Until now, we could attribute the 

 steady rise to normal climatic changes 

 that have occurred throughout the 

 Earth's history. 



But we've thrown another variable 

 into the equation, Riggs says. And it's 

 called the greenhouse effect. 



Increased concentrations of carbon 

 dioxide and other gases, the result of 

 our burning massive amounts of fossil 

 fuels over the last 150 years, are cre- 

 ating a warmer Earth. 



Scientists say the higher tempera- 

 tures, even if only a degree or two, will 

 cause more melting of polar ice caps. 

 And, as the ocean warms, it expands, 

 causing an additional rise. 



The result is an acceleration of an 

 already rising sea level. 



Riggs says the oceans have been 

 rising at a rate of about one-half to 

 three-quarters of a foot per century. 

 And in the history of the world, sea 

 level fluctuations are nothing unusual. 



During one ice age, sea level was 

 so low that much of the continental 

 shelf was exposed. In warmer times, 

 the polar ice caps melted and the 

 oceans swelled. For example, about 5 

 million years ago the Atlantic Ocean 

 reached slightly west of Wilson, Riggs 

 says. 



But the greenhouse effect adds a 

 man-made twist to a natural phenom- 

 enon. So far, Riggs is hesitant to say 

 whether we're already seeing a rise 

 in sea level because of the green- 

 house effect. 



"This is all projection," he says. 

 "From this point on, it goes into the 

 realm of theory and models." 



In the past few years, scientists have 

 begun feeding data into mathematical 

 equations to come up with estimates 

 of if, when and how much sea level 

 will rise. 



Their science is still primitive. But 

 preliminary projections don't look good. 



For example, studies by the U.S. 

 Environmental Protection Agency esti- 

 mate that seas will rise between 4 and 

 7 feet by the year 2100. But some 

 scientists predict the oceans could 

 rise as much as 12 feet. 



Riggs' projections are more conser- 

 vative. He expects a 3-foot sea level 

 rise along the coast within the next 

 century. 



But even with the most conservative 

 estimates, the Tar Heel coast is in for 

 big change, Riggs says. 



"North Carolina 400 years from now 



will have quite a different shape," 

 Riggs says. 



"This could have a significant im- 

 pact on a state like North Carolina 

 where a half a dozen of the coastal 

 counties are just as flat as a pancake," 

 he says. 



Even a slight rise in the oceans 

 could wreak havoc in coastal counties 

 where much of the land is barely 

 above sea level, says Len Pietrafesa, a 

 physical oceanographer at North 

 Carolina State University. 



And just because sea level rises a 

 foot, it doesn't mean it claims only a 

 foot of land, he adds. 



"The water level may be one foot 

 higher, but that could mean in some 

 places the movement of water could 

 be as little as 1,000 feet inland or as 

 much as 10,000 feet inland. And that's 

 between one-fifth of a mile to 2 miles," 

 Pietrafesa says. "Obviously that's not 

 good." 



Shoreline movement 

 depends on the land slope. 



