Sea level change

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Sea level can change, both globally and locally (relative sea level change) due to

  1. a change in ocean volume as a result of a change in the mass of water in the ocean,
  2. changes in ocean volume as a result of changes in ocean water density,
  3. changes in the shape of the ocean basins and changes in the Earth’s gravitational and rotational fields, and
  4. local subsidence or uplift of the land.

Global mean sea level change resulting from change in the mass of the ocean is called barystatic. The amount of barystatic sea level change due to the addition or removal of a mass of water is called its sea level equivalent (SLE). Sea level changes, both globally and locally, resulting from changes in water density are called steric. Density changes induced by temperature changes only are called thermosteric, while density changes induced by salinity changes are called halosteric.

Barystatic and steric sea level changes do not include the effect of changes in the shape of ocean basins induced by the change in the ocean mass and its distribution.

Sea-level rise as it relates to climate change is caused by two major factors. First, more water is released into the ocean as glaciers and land ice melts. Second, the ocean expands as ocean temperatures increase. Both of these consequences of climate change are accelerating sea-level rise around the world, putting millions of people who live in coastal communities at risk.


NASA Global Climate Change
Climate Change: Global Sea Level
Surging Seas: Risk Finder