State of the steric sea level rise, 1955-2003

The warming of the world ocean is consistent with the amount of warming expected as a result of the observed increase in greenhouse gases in earth's atmosphere.

The observed ocean warming has contributed approximately 20 mm to global average sea level during this time period. This is simply the phenomenon of salt water expanding when it is warmed. This expansion effect (or contraction if cooling occurs) is known as the “thermosteric component of sea level change.”

This estimate is similar to previous estimates even after recently identified instrumentals errors are corrected for and additional historical data has been added to the scientists' database. The thermosteric component of sea level change is only one of several phenomena affecting sea level. Others include the melting of glaciers, the transfer of liquid water between the continents and oceans, and the impoundment of water by dams.

Levitus will also describe the changes in global sea level, resulting from changes in the distribution of temperature and freshwater in the world ocean during the same 1955 – 2008 time scale.