Two main factors contributed to observed sea level rise. The first is thermal expansion: as ocean water warms, it expands.

The second is from the contribution of land-based ice due to increased melting

Between 1870 and 2004, Global average sea levels rose 17 cm

From 1950 to 2009, measurements show an average annual rise in sea level of 1.7 ± 0.3 mm with satellite data showing a rise of 3.3 ± 0.4 mm from 1993 to 2009, a faster rate of increase than originally estimated.