Between 1870 and 2004, global average sea levels rose 195 mm (7.7 inches), or almost  20 cm.

From 1950 to 2009, measurements show an average annual rise in sea level of about 1.7 mm per year, with satellite data showing a rise of about 3.3 mm per year from 1993 to 2009, a much faster rate of increase than previously estimated.

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. The major store of water on land is found in glaciers and ice sheets.


Sea level rise is one of several lines of evidence that support the view that the climate has recently warmed. The global community of climate scientists confirms that it is very likely that human-induced (anthropogenic) warming contributed to the sea level rise observed in the latter half of the 20th century.