Source: NOAA, Satellite and Information Service.
Global mean sea level change is the outcome of two processes on the volume taken by the oceans on the earth’s surface. First, changes in the quantity of heat accumulated by the oceans and their salinity level will impact the density of oceanic water and its volume. Warm water has a lower density than cold water, so it takes more volume. Saltwater has a higher density than freshwater, so it takes less volume; the Atlantic has a higher salinity level than the Pacific. The second process involves exchanging water between oceanic masses and other water reservoirs, namely polar ice caps and ice sheets. An increase in the global temperature involves releasing additional water from these reservoirs into the oceans, increasing their mass. Although estimates vary, those provided by the Laboratory for Satellite Altimetry (NOAA) indicate an average global trend in sea level rise since 1992 in the range of about 3 mm per year.