If it took 100 years for the oceans to rise eight inches, why should we believe they'll rise 55 inches in the next 90 years?

Scientists to create the most detailed map of California coastline ever assembled - San Jose Mercury News

The ocean already has risen 8 inches over the past 100 years, as measured by tidal gauges at Fort Point in San Francisco. Computer models run by the Scripps Institution of Oceanography, the U.S. Geological Survey and other research centers predict at the current rate of global warming, sea level could rise another 55 inches — or nearly five feet — by the end of this century as ice sheets continue to melt and the warmer ocean water expands.