Sea level the warmer water expands. For at least the last 100 years, sea level has been rising at an average rate of about per year. Most of this rise can be attributed to the increase in temperature of the sea and the resulting slight thermal expansion of the upper of sea water. Additional contributions, as much as one-quarter of the total, come from water sources on land, such as melting snow and glaciers and extraction of groundwater for irrigation and other agricultural and human uses. Pilots can estimate height above sea level with an altimeter set to a defined barometric pressure.
Sea level equation the sea surface constant for a specific deglaciation chronology and viscoelastic earth model. The SLE theory was then developed by other authors as Mitrovica & Peltier, Mitrovica et al. and Spada & Stocchi. In its simplest form, the SLE reads where formula_2 is the sea–level change, formula_3 is the sea surface variation as seen from Earth's center of mass, and formula_4 is vertical displacement. In a more explicit form the SLE can be written as follow: where formula_6 is colatitude and formula_7 is longitude, formula_8 is time, formula_9 and formula_10 are the densities of ice and water, respectively, formula_11 is