Observing Long-Term Mass Changes in the Global Ocean and Ice Sheets from Satellite Gravimetry: 1993–2023

Abstract

Global ocean mass change is a major driver of present-day global mean sea level (GMSL) rise and a key indicator of climate change. Over the past three decades, mass loss from the Greenland and Antarctic ice sheets has been a major contributor to global ocean mass change. Since 2002, GRACE/-FO has provided invaluable observations of ice-sheet and ocean mass changes, whereas direct observations remain limited for the pre-GRACE era. Here, we use time-variable gravity fields derived from GRACE/-FO, satellite laser ranging (SLR) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) to estimate long-term mass changes in the global ocean and ice sheets since 1993, the beginning of the high-precision satellite altimetry era. Major challenges associated with signal leakage and geocenter motion are addressed using a global forward-modeling technique. Using these satellite-gravimetry-based estimates, we reconcile the GMSL budget and compare ice sheet mass changes with estimates from independent techniques. Our results demonstrate the added value of SLR and DORIS observations in complementing the GRACE/-FO record and highlight the importance of further investigations into historical satellite gravimetry data to improve estimates of long-term mass changes in the Earth system.