Regional modeling of peripheral glaciers in Greenland: Implications for mass balance, freshwater runoff, and sea level rise

Peripheral glaciers (PGs, i.e., glaciers that are dynamically decoupled from the ice sheet) play a significant role in the mass balance and freshwater runoff of Greenland's land ice. Their evolution has implications for the sea level, global climate and ocean circulation, as well as for coastal communities and ecosystems. In order to accurately model the contribution of PGs to Greenland's overall mass balance and freshwater supply, it is necessary to consider their characteristics that set them apart from the main ice sheet. In this study, we used the Open Global Glacier Model (OGGM) to conduct large-scale regional modeling of approximately 19,000 PGs and project future mass losses, freshwater runoff, and sea level contributions under different climate scenarios. Our results show that PGs are likely to experience 29 % to 52 % of mass loss compared to their 2020 levels by the end of the 21st century, resulting in 10 mm to 19 mm of sea level rise under SSP126 and SSP585, respectively. Under the high emission scenario, PGs are expected to contribute 184 Gt yr^-1 of liquid freshwater and 3 Gt yr^-1 of calved solid ice to the ocean during 2020-2100, affecting ocean density, circulation, and mixing. Peakwater is projected for the 2080s under SSP585, after which annual freshwater contributions are expected to decline due to reduced glacier area. Regional mass and freshwater balance differences were found to be influenced by local climate, ocean-ice interaction, proportion of marine-terminating glaciers, and initial glacier volume. The central-west, southeast, and central-east subregions will experience the largest mass losses (79 %, 69 %, and 63 % of mass in 2020), with peakwater occurring earlier than for all PGs considered together under SSP585. The northeast subregion is expected to contribute 35 % of total liquid freshwater, 73 % of solid ice calving, and 37 % of sea level rise, despite lower mass loss (wrt 2020) due to regional conditions (i.e., climate, glacier geometries, and surrounding ocean). Submarine melting is likely to impact the mass balance of marine-terminating PGs, but further research is needed to explore this effect at a regional scale. This study highlights the importance of considering the distinct behavior of PGs in modeling Greenland's freshwater balance and understanding the factors that influence their mass changes.