Climate change, along with the associated ice-shelf melting, contributes to sea level rise. However, the calculations linking the temperature records with ice melt leave an unexplained 12 cm/century rise in the actual levels - as measured around the world by tide gauges (and recently by satellite radar). Put another way, the levels are rising 3 to 4 times faster than can currently be explained.
This anomaly, called the Attribution Problem by geoscientists, has been the subject of intense debate. There are various theories revolving around the general observation that : “either the tide gauge estimates are too high, as has been suggested recently, or one (or both) of the mass and volume estimates is too low.”
A new theory (2015) suggests the idea that the anomalies may be caused by changes in the size of the Earth itself.
“Major effects on sea-level could come from ongoing relaxation of curvature variations that are peculiar for an expanding globe.”
Source:Sea Level Enigmatic Rising : New Perspectives from an Expanding Globe
Further reading : The Puzzle of Global Sea-Level Rise in Physics Today, Volume 55, Issue 3.