We have computed estimates of the rate of vertical crustal motion from differences of sea level measurements made by the TOPEX/POSEIDON radar altimeter and a globally distributed network of 114 tide gauges. A rigorous error analysis was performed which suggests the accuracy of the estimated vertical rates is approximately 1–2 mm/year for roughly half of the tide gauges, which is sufficiently accurate to detect a variety of geophysical phenomena. While only a cursory analysis of the estimated crustal motion rates was performed, we observed many interesting phenomena including significant uplift at volcanic islands in the Pacific and uplift of 7–9 mm/year along the southwest coast of Alaska. The results reported here will be useful in a variety of geophysical studies, as well as for validation of similar estimates of vertical crustal motion provided by precise geodetic techniques such as SLR, DORIS, GPS, and VLBI.

Tide gauge data are used to estimate trends in global sea level for the period from 1955 to 2007. Linear trends over 15-yr segments are computed for each tide gauge record, averaged over latitude bands, and combined to form an area-weighted global mean trend. The uncertainty of the global trend is specified as a sampling error plus a random vertical land motion component, but land motion corrections do not change the results. The average global sea level trend for the time segments centered on 1962-90 is 1.5 6 0.5 mm yr 21 (standard error), in agreement with previous estimates of late twentieth-century sea level rise. After 1990, the global trend increases to the most recent rate of 3.2 6 0.4 mm yr 21 , matching estimates obtained from satellite altimetry. The acceleration is distinct from decadal variations in global sea level that have been reported in previous studies. Increased rates in the tropical and southern oceans primarily account for the acceleration. The timing of the global acceleration corresponds to similar sea level trend changes associated with upper ocean heat content and ice melt.

important to planning for future sea level rise. Here, we detail the network for observing sea level and its components, underscore the importance of these observations, and emphasize the need to maintain current systems, improve their sensors, and supplement the observational network where gaps in our knowledge remain.