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We believe that the actual rate of sea level rise is more 

 likely to fall between the two mid-range estimates than outside 

 of them. Because the high and low scenarios employ more extreme 

 assumptions, neither is likely to occur. However, the possibility 

 can not be ruled out. 



SEA LEVEL RISE WILL ACCELERATE UNDER ALL ASSUMPTIONS 



Even in the low scenario, sea level will rise twice as 

 fast as its historical rate in the next 20 years, and from 

 2000 to 2025, at three times the historical rate. In the high 

 scenario, the sea will rise about ten times its historical 

 rate from 1980 to 2025. Over the last quarter of the 21st 

 century, the nigh scenario predicts the sea to rise at over 40 

 times the historical rate. 



The mid-range scenarios predict that from 1980 to 2000, 

 sea level will rise almost as much as it has in the last century. 

 Given local trends on much of the East and Gulf Coasts of the 

 United States, shoreline retreat in the next 20 years could 

 be one-half that of the past century. In the following 25 years, 

 worldwide sea level would rise at about eight times the historical 

 rate, creating much greater erosion and flooding problems. 

 Thus, in the next four decades (within the lifetimes of many 

 projects now under design) the sea is likely to rise twice as 

 much as it has in the last century. 



AN ALTERNATIVE METHOD PRODUCES SIMILAR ESTIMATES OF SEA LEVEL RISE 



To cross check our projections, we estimated sea level 

 changes by another method: extrapolating past associations 



