Melting ice shelves Of AnTarctica

Sea level rise (SLR) is one of the most damaging impacts of climate change, threatening the economy, ecology, and entire existence of coastal regions worldwide. Global mean sea level has risen by ~10 cm since 1992, with land ice loss accelerating. Future sea-level rise is set to become dominated by the highly uncertain behaviour of the Antarctic ice sheet, both in its current contribution to SLR as for its future demise. It is now abundantly clear that this uncertainty is ultimately rooted in the processes that deliver heat from the Southern Ocean and the atmosphere to Antarctica and how they affect the ice shelves that surround
75% of the Antarctic coastline and can be considered the gatekeepers of Antarctica.

Currently, most ice mass loss changes observed in Antarctica appear to have resulted from ice shelf weakening through melting in response to an increase in the circulation of warm, and probably warming, Circumpolar Deep Water beneath the ice shelves.
Adjacent to this, ice shelf fracturing and ultimately breakup is guided by extremes in surface temperature leading to surface melt, sea-ice disintegration, or large swells. While efforts have already been made to observe ice shelf melting, weakening and ice sheet acceleration, the processes leading to ice shelf demise remain a major uncertainty. This uncertainty is mainly the result of our
limited quantitative understanding of many of the processes that control ice shelf weakening and their interaction. Several processes have been identified as key for future ice shelf weakening and ice shelf stability ranging from (i) ocean induced localized basal melting, (ii) surface meltwater infiltration, refreezing and ponding, and (iii) the changes they incur to the rheology of the ice shelf. The impact of these atmospheric and oceanic processes on the rheology and stress distribution remains poorly quantified, often resulting in an underestimation of present and future mass loss in current ice sheet models that lack a proper
representation of these weakening processes.

The MOAT consortium, consisting of ULB, KULeuven and VUB, aims to tackle this knowledge gap regarding ice shelf instability processes by direct and continuous measurements of basal melting, surface melting and snapshots of ice shelf rheology using radar and photonic sensors. Given almost two decades of measurements on the Roi Baudouin Ice Shelf (RBIS), it will also allow us to determine the evolution of melt intensity and patterns over time. MOAT will further benefit from ongoing SCAR-RINGS airborne campaigns in combination with frequent, high-resolution, multi-source satellite imagery across all Antarctic ice shelves to put observed changes in a broader spatial and temporal perspective. The in-situ and remote sensing measurements will be used to improve the representation of surface and basal melt processes in regional climate models (MAR) and ice sheet models (Kori-ULB). These improvements will be beneficial for ongoing and future work focusing on projections of the contribution of the Antarctic ice sheet to sea level rise.

The project will provide a contribution to ongoing SCAR-RINGS initiative, aiming at improving our knowledge of the current mass changes of the Antarctic ice sheet across the grounding line and on ice shelves. It also relies on close collaboration with international projects, such as OCEAN:ICE (EU-Horizon Europe) and SOOS (Southern Ocean Observing System). MOAT also builds
on the knowledge of the ongoing HiRISE (NWO-Groot) project, involving ULB and KULeuven partners and aiming at improving our understanding of ice shelf processes. The MOAT project will generate important insights into the sensitivity of Antarctica to climate change and climate variability, and on the role of Antarctic ice shelf stability in a changing climate. Moreover, it will strongly support the (coupled) ice sheet/climate model communities as it will enable a more accurate representation of ice shelf processes in their models and reduce the uncertainties due to ice shelf weakening in the next generation of these models for projecting sea level rise. These improvements will therefore be pivotal for future ice sheet projections within the framework of CMIP7/ISMIP7 and forthcoming IPCC reports.