Global Glacier Mass Loss estimated from GRACE and GRACE-FO Satellite Observations (2002-2019)

Glaciers outside of the ice sheets are important contributors to sea level rise. Although their overall mass balances can be estimated by upscaling local field measurement, direct observations with global coverage are only feasible with satellite remote sensing. Satellite gravimetry of the Gravity Recovery and Climate Experiment (GRACE) showed that between 2002 and 2016, glaciers lost mass at a rate of 199 ± 32 Gt yr−1, equivalent to a cumulative sea level contribution of 8 mm. After about one year of interruption following the end of the GRACE science operations in June 2017, GRACE Follow-On (GRACE-FO) now allows us to extend the time series of its predecessor starting June 2018. In this work, we provide updated estimates of the global glacier annual mass balance for 2002 and 2019 based on GRACE/GRACE-FO, and present regional changes with a focus on recent years. Furthermore, we discuss the different uncertainties entering our mass balances and compare our estimates to those based on upscaling in-situ measurements.