Topex/Poseidon altimeter data collected since late 1992 are being used in an attempt to obtain an "instantaneous" measurement of the rate of global sea level rise. By instantaneous, we mean a determination of the present rate over a period that is short compared to the century-long average of about 2 mm per year derived from tide gauges.
For recent results, see site at the University of Colorado
Also see:
Nerem et al., "Variations in global mean sea level associated with the 1997-1998 ENSO event: Implications for measuring long term sea level change, Geophys. Res. Lett., 26(19), 3005-3008, 1999.
Nerem and Mitchum, "Observations of sea level change from satellite altimetry", In: Sea Level Rise, History and Consequences. Douglas, Kearney, and Leatherman, eds., Academic Press, San Diego, CA, pp. 121-164, 2001.
