Relative sea levels from tide-gauge records.

Mean annual sea levels at 247 tide-gauge stations of the world exhibit a general rise of relative sea level of about 3 mm/year during the past 40 years. In contrast, general uplift of the land is typical of high northern latitudes, where unloading of the crust by melt of Pleistocene ice sheets is significant. Erratic movements are typical of belts having crustal overthrusting and active volcanism. Short-term (5- and 10-year) records reveal recent changes in rates, but such short time spans may be so influenced by climatic cycles that identification of new trends is difficult, especially with the existing poor distribution and reporting of tide-gauge data.