Changes in Sea Level
The main causes of change in sea level include thermal expansion of oceans and melting of the glaciers and ice caps.
- Global average sea level has risen since 1961 at an average rate of 1.8 [1.3 to 2.3] mm/yr and since 1993 at 3.1 [2.4 to 3.8] mm/yr, with contributions from thermal expansion, melting glaciers and ice caps, and the polar ice sheets. (IPCC, 2007)
- The contribution from thermal expansion is estimated to be 0.42 0.12 mm/year. With significant decadal variations, the contribution from glaciers, ice caps, and ice sheets is estimated to be 0.7 0.5 mm/year.
Sea level changes show geographical variation because of several factors, including the distribution of changes in ocean temperature, salinity, wind pattern, and ocean circulation.
The following graph shows changes in sea level.
Changes in sea level relative to the corresponding averages for the period 1961-1990
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