Quantcast Long-Term Sea Level Rise

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Solana Beach Coastal Preservation Association
August 20, 1998
Project No. 1831
Page 19
Beach area, assuming a design long-term sea level rise of 1.0 foot, the likely
maximum design stillwater elevation would be 7.5 feet (MSL).
3.3
Long-Term Sea Level Rise
Changes in sea level result in significant changes in the shoreline location. Three general
sea level conditions are recognized: rising, falling, and stationary. The rising and falling
stages result in massive sediment release and transport, while the stationary stage allows
time for adjustment and reorganization towards equilibrium. Major changes in sea level
during the Quaternary period were caused by worldwide climate fluctuation, resulting in at
least 17 glacial and interglacial stages in the last 800,000 years and many before then
(Shackleton and Opdyke, 1976). Worldwide sea level rise associated with the melting of
glaciers is commonly referred to as Aglacio-eustatic@ or Atrue@ sea level rise. During the
past 200,000 years, eustatic sea level has ranged from about 150 meters below the
present-day level, to possibly as high as about 10 meters above the present-day level. If all
of the ice presently on earth were to melt, sea level would rise about 78 meters (256 feet)
above the present level (Barry, 1981).
Sea level changes during the last 18,000 years (Figure 7; USCOE, 1991) have resulted in
an approximately 400-foot rise in sea level, when relatively cold global climates of the
Wisconsin ice age started to become warmer, melting a substantial portion of the
continental ice caps (Curray, 1960; 1961). Sea level curves show a relatively rapid rise of
about 1 meter per century, from about 18,000 years before present to about 8,000 years
ago, as indicated in Masters and Fleming (1983). About 8,000 years ago, the rate of sea
level rise slowed, ultimately to a relatively constant rate of about 10 centimeters per century
since about 6,000 years ago (Curray, 1960; 1961; 1965). Most researchers agree that,
along the southern California coastline, the sea level approximately 6,000 years ago was 12
to 16 feet below its current elevation (Curray, 1960, 1965; Inman and Veeh, 1966). More
importantly, the world=s coastlines, including that of California, have been shaped largely
within this 6,000-year period, with the sea at, or within 16 feet of, its present level (Bird,
1985).



 


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