Surface Elevation Changes and Mass Balance of the Greenland Ice Sheet from 2019 to 2024 from ICESat-2 Observations using a new MECEM model

As one of the main contributors of global sea level rise, the Greenland Ice Sheet (GrIS) has been experiencing significant thinning and losing ice mass since the Earth observation era using satellites. ICESat-2, equipped with the photon-counting altimetric technology, provides an unprecedented elevation accuracy of 2-4 cm and extremely high spatio-temporal coverages for reducing uncertainties in mass balance estimation of the ice sheet. We have developed a multi-temporal elevation change estimation model (MECEM) that is especially tailored for processing the ICESat-2 data and estimating mass changes. Here, we present our assessment of surface elevation change across the GrIS and its peripheral glaciers, using ICESat-2 observations acquired between March 2019 and March 2024. A validation against GNSS-derived elevation change rates near the Summit Station during 2022–2024 demonstrates a close agreement. In addition, a comparison with independent elevation change products indicates a strong consistency, particularly over interior high-elevation regions. Our results reveal increased thinning in the southeast and southwest coastal regions and major outlet glacier systems, such as Jakobshavn Isbræ and Helheim Glacier. The ablation zone (< 1500 m) experiences a rapid thinning at an average rate of −0.48 ± 0.04 m yr⁻¹, while the interior region (≥ 1500 m) remains relatively stable with a slight thickening. The mean surface elevation change rate over the entire GrIS is −0.10 ± 0.02 m yr⁻¹. We further convert the surface elevation changes to ice mass changes by using corrections of firn air content and solid earth. A comparison with other studies and a discussion are also provided.