Coastlines are not static. They move. I first learned this while hiking in Texas. One park had a map of the Texas shoreline over several hundred thousand years. The place I was standing to read the sign had once been under water.
According to the EPA, the coastal water line is moving up and in.
“Sea levels are rising worldwide and along much of the U.S. coast. (IPCC, 2007) Tide gauge measurements and satellite altimetry suggest that sea level has risen worldwide approximately 4.8-8.8 inches (12-22 cm) during the last century (IPCC, 2007). A significant amount of sea level rise has likely resulted from the observed warming of the atmosphere and the oceans.
“Satellite measurements estimate that sea level has been rising at a rate of 9 to 15 inches per century (2.4-3.8 mm/yr) since 1993, more than 50% faster than the rate that tide gauges estimate over the last century. (IPCC, 2007)”
For a more thorough analysis of the possible causes (and inconsistencies), go to the above website.
Click here for the EPA’s posted estimates of future sea level changes.