Eustatic Sea Level

Eustatic sea level is the global mean sea level measured as a change in the total volume of ocean water, independent of local land movement. It rises and falls with two main drivers: thermal expansion of warming water (steric change) and the mass added by melting glaciers and ice sheets (barystatic change). Eustatic change is distinguished from relative sea level, which a tide gauge records by combining the eustatic signal with local vertical land movement from glacial isostatic adjustment, tectonics, or subsidence. Satellite altimetry measures the eustatic component near-directly against the geoid; the present global mean rate is about 3 to 4 mm per year, accelerating.