People have been warning me for years that rising sea levels will erode the coastline. It’s hard to fathom (pun not intended) what that really means. Fortunately a new scientific method is being developed by the American government to quantify the situation. A report called “National Assessment of Shoreline Change: Historical Shoreline Change in the Hawaiian Islands” shows a fairly significant (14 mile) loss of beach.

Because the U.S. population continues to shift toward the coast where valuable coastal property is vulnerable to erosion, the U.S. Geological Survey (USGS) is conducting a national assessment of coastal change.

[…]

A principal purpose of the USGS shoreline change research is to develop a common methodology so that shoreline change analyses for the continental U.S., portions of Hawaii, and Alaska can be updated periodically in a consistent and systematic manner. The primary objectives of this study were to (1) develop and implement improved methods of assessing and monitoring shoreline movement, and (2) improve current understanding of the processes controlling shoreline movement.

Ok, so they’re improving our understanding…and then they give a huge caveat:

Rates of shoreline change presented herein may differ from other published rates, and differences do not necessarily indicate that the other rates are inaccurate. Some discrepancies are to be expected, considering the many possible ways of determining shoreline positions and rates of change, and the inherent uncertainty in calculating these rates. Rates of shoreline change presented in this report represent shoreline movement under past conditions and are not intended for use in predicting future shoreline positions or future rates of shoreline change