NUMEROUS PROCESSES CAUSE SEA LEVEL CHANGE ON TIME-SCALES RANGING FROM A FEW DAYS TO CENTURIES (FIG.1). AVERAGED OVER THE GLOBAL OCEANS SEA LEVEL ROSE AT A MEAN RATE OF 1.7 MM/YR OVER THE 20TH CENTURY INCREASING TO 3.2 MM/YR OVER THE PAST TWO DECADES [E.G. CHURCH ET AL. 2013]. SEA LEVEL RISE SINCE 1993 IS DUE MAINLY TO THERMAL EXPANSION OF THE OCEANS (1.1 MM/YR) LOSS OF GLACIER ICE (0.8 MM/YR) AND LOSS OF GREENLAND AND ANTARCTIC ICE SHEETS (0.6 MM/YR) WITH SMALLER CONTRIBUTIONS FROM GROUNDWATER EXTRACTION [E.G. CHURCH ET AL. 2013]. ALTHOUGH HYDROLOGIC INCREASE IN CONTINENTAL WATER REDUCED THE RATE OF SEA LEVEL RISE BY 0.7 MM/YR OVER THE PAST 12 YEARS [REAGER ET AL. 2016]. ON LOCAL SCALES HOWEVER THE RATE OF REGIONAL SEA LEVEL CHANGE CAN BE MANY TIMES LARGER THAN THE GLOBAL AVERAGE DUE TO CHANGES IN OCEAN AND ATMOSPHERIC CIRCULATION PATTERNS THE GRAVITATIONAL AND DEFORMATIONAL EFFECTS OF LAND ICE MASS CHANGES TECTONICS ALONG THE COAST AS WELL AS LAND SUBSIDENCE DUE TO GROUNDWATER WITHDRAWAL AND SOIL COMPACTION. FOR COASTAL PLANNING IT IS THIS RELATIVE SEA LEVEL CHANGE THAT COMBINES THE EFFECTS OF OCEAN VOLUME CHANGE AND VERTICAL LAND MOTION THAT IS OF PRIMARY IMPORTANCE. SINCE 1993 OUR KNOWLEDGE OF THE MAGNITUDE VARIABILITY AND SOURCES CONTRIBUTING TO THE OCEAN VOLUME AND MASS COMPONENTS OF SEA LEVEL CHANGE HAVE IMPROVED DRAMATICALLY BY USING TIDE GAUGE RECORDS AND SATELLITE OBSERVATIONS (FIG. 1) AS WELL AS REGIONAL AND GLOBAL CIRCULATION MODELS.