Understanding Sea Level
What are we looking at?
This jagged line shows losses from ice sheets and glaciers on the Antarctic continent since May 2002, expressed in gigatonnes (billions of metric tons) of ice mass – the “weight” of the ice. (See an animated map of these changes.) The blue line (seen when you click and drag to zoom in) shows how much uncertainty, high or low, is associated with these measurements. (Uncertainty, or the “give and take” number, describes the range from the mean, or average, within which there is a high probability that the true number resides.)
These measurements come from the retired GRACE (Gravity Recovery and Climate Experiment) satellites, and GRACE Follow-On, the successor mission to GRACE that launched in 2018.
Why do we care?
Antarctica, like Greenland, is losing ice, although not as fast. For every 360 gigatonnes of land ice lost, the ocean rises by 1 millimeter. Since May 2002, sea levels have risen by about 2.5 inches, or 63 millimeters. Sea level rise increases coastal flooding and eventually will inundate some coastal communities.
Reference: Watkins et al., 2015, doi: 10.1002/2014JB011547; GRACE and GRACE Follow-On JPL RL06Mv2 data
Gravity Recovery And Climate Experiment (GRACE), GRACE Follow On