In preparing the last global temperature blog I went back and read much of the Hadley Center material, including a paper on the rise of global sea level.
The data set goes back a century. The range of estimates, based on the rudimentary amount of data available, is from a decline in the global sea level of 7 inches over the past 100 years due to absorption of sea water into the Antarctic ice sheet, to a rise of 16 inches. Based on actual shoreline measurements the range is from 4 inches to 8 inches.
The article suggests that the strongest evidence for a rise in global sea level is for a rise of 6 inches over the past hundred years.
All projections of future sea level changes are based on the changes (whatever they were) over the past hundred years. We could have a declining sea level or a modestly rising one of a foot or more.
Help, call Noah, the world is coming to an end. Thank goodness I live more than 2,000 inches above sea level in San Francisco.