Sea level change tracked along U.S. coastline

Abstract

When long‐term changes in coastal water level are recorded from a fixed point on land, the absolute change in the level of the ocean or the land is not being measured; the difference between two independent variables is. Longterm changes in the level of the ocean are caused by changes in ocean temperatures, salinities, currents, winds, and atmospheric pressures, or changes in the total amount of water in the ocean basins. Long‐term changes in land elevation are caused by vertical tectonic motions due to glacial rebound or plate boundary interactions, volcanic processes, deposition and compaction of sediments, or the extraction of oil, gas, or water. For many purposes, only the relative change in water level is of interest; for other purposes, it is important to separate the fluctuations of the ocean from vertical land movement. Information necessary for interpreting changing water levels at many locations along the U.S. coastline is now available online from NOAA (tidesandcurrents.noaa.gov).