In the frame of the Climate Change Initiative (CCI) project, a "Sea Level" Essential Climate Variable was defined. Sea Level, or Mean Sea Level (MSL) is an average of the ocean surface height over an area or over the whole ocean (Global Mean Sea Level). However, what are really sought are the variations of this mean sea level along time.
Sea level is an indicator very sensitive to climate variability. It responds to change in several components of the climate system (atmosphere warming, ice melt, changes in hydrological cycles...).
Precise monitoring of changes in the mean level of the oceans is vitally important for understanding not just the climate but also the socioeconomic consequences of any rise in sea level.