Glacier and ice-sheet mass

Glacier and ice-sheet mass covers the EO question of where land ice is gaining or losing mass, how fast that change is occurring, and how it affects sea-level and freshwater-risk decisions. Spaceborne gravimetry is the most direct satellite route for large ice sheets and large glacier basins: GRACE and GRACE-FO track monthly surface mass anomalies, including ice sheets and glaciers, as part of the global water and mass-change record.^[1]

Altimetry is the main complementary route. ICESat-2 measures elevation over ice sheets and glaciers, while the ATL15 land-ice product turns ICESat-2 observations into gridded height-change fields for Antarctica and Arctic land ice.^[2][3] Radar altimetry also contributes to ice monitoring; ESA describes CryoSat as dedicated to sea-ice thickness and changes in the Greenland and Antarctic ice sheets.^[4]

Mass estimates from elevation change require density, firn, and surface-mass-balance assumptions. InSAR and SAR change methods support glacier-dynamics interpretation, but they do not replace gravimetry or altimetry as the primary mass-change measurement route.