Periodic Reporting for period 2 - OCEAN ICE (Ocean Cryosphere Exchanges in ANtarctica: Impacts on Climate and the Earth system)
Berichtszeitraum: 2024-05-01 bis 2025-10-31
The Antarctic Ice Sheet and Southern Ocean represent critical components of Earth's climate system, yet their complex interactions and future behaviour remain among the most significant sources of uncertainty in climate projections. As global temperatures rise, understanding how changes in these polar regions will affect sea-level rise, ocean circulation patterns, and global climate has become increasingly urgent. The melting of Antarctic ice has profound implications not only for coastal communities worldwide but also for deep-water formation processes and major ocean circulation systems, such as the Atlantic Meridional Overturning Circulation (AMOC), which plays a crucial role in regulating the European climate. Despite this importance, substantial data gaps in the Southern Ocean and a limited understanding of ice-sheet-ocean-climate feedbacks have hindered our ability to make reliable predictions about these changes and their cascading effects on the planet. OCEAN ICE tackles the well-documented data scarcity in the Southern Ocean by gathering new circumpolar and Atlantic Ocean observations, combining in-situ measurements with Earth Observation data, with particular emphasis on ESA-produced satellite datasets. These valuable observations are assimilated into improved ice-sheet, ocean, and climate models, enabling the production of new estimates of ice-sheet melt and its cascading impacts on ocean circulation, including the critical AMOC.
OCEAN ICE produces projections of societally relevant environmental changes spanning decadal to multi-centennial timescales, addressing one of the most pressing questions facing policymakers and society: how quickly and dramatically these changes will unfold. The project also assesses the potential for crossing critical ice sheet "tipping points". It evaluates their consequences for ocean circulation and global climate stability—knowledge essential for understanding whether we face gradual or potentially abrupt transitions in Earth's climate system. By advancing the state of the art in coupled ice sheet-climate modelling, OCEAN ICE directly supports international climate assessments, including contributions to the Intergovernmental Panel on Climate Change and World Ocean Assessment, it delivers improved assessments of European climate impacts and provides policymakers with actionable information about risks and timescales, for climate adaptation planning, coastal protection strategies, and long-term policy development.
OCEAN ICE produces projections of societally relevant environmental changes spanning decadal to multi-centennial timescales, addressing one of the most pressing questions facing policymakers and society: how quickly and dramatically these changes will unfold. The project also assesses the potential for crossing critical ice sheet "tipping points". It evaluates their consequences for ocean circulation and global climate stability—knowledge essential for understanding whether we face gradual or potentially abrupt transitions in Earth's climate system. By advancing the state of the art in coupled ice sheet-climate modelling, OCEAN ICE directly supports international climate assessments, including contributions to the Intergovernmental Panel on Climate Change and World Ocean Assessment, it delivers improved assessments of European climate impacts and provides policymakers with actionable information about risks and timescales, for climate adaptation planning, coastal protection strategies, and long-term policy development.
OCEAN ICE has successfully consolidated the foundation established in the project's initial phase and begun generating significant new scientific and technical results. The work has encompassed a comprehensive range of activities spanning fieldwork operations, instrumental deployments and data recovery, advanced Earth Observation data processing, and sophisticated model development. These efforts have yielded substantial progress in understanding Antarctic Ice Sheet and Southern Ocean processes, while also establishing a robust information ecosystem that facilitates both internal project coordination and external engagement with stakeholders and the broader scientific community. The project has delivered numerous milestones and deliverables addressing diverse technical challenges, from the deployment of autonomous ocean floats to the configuration of complex ice sheet and climate models, and the generation of novel satellite-based datasets. Among the most significant achievements has been the successful execution of extensive observational campaigns in some of the planet's most challenging and scientifically critical environments. OCEAN ICE has conducted a substantial number of instrument deployments followed by successful data recovery from critically underobserved regions surrounding Antarctica. These operations have yielded unprecedented measurements from beneath winter sea ice, from cavities beneath both "warm" and "cold" ice shelves where ocean-ice interactions drive melt processes, and from the deepest locations in the Southern Ocean. On the data synthesis and modelling front, OCEAN ICE has produced state-of-the-art hydrographic climatologies for the Southern Ocean, representing a significant advancement in our understanding of ocean conditions in this data-sparse region. These comprehensive mappings have subsequently been utilised to enhance high-resolution ocean models and to provide improved initial conditions for ice sheet models, directly addressing the challenge of model initialisation in regions with limited observational constraints. Significant progress has been made in representing iceberg dynamics within numerical modelling frameworks. OCEAN ICE has developed new spatial distributions of iceberg meltwater, which are essential for accurately representing freshwater input to the Southern Ocean in climate simulations.
OCEAN ICE has built upon the field deployments from the first period to harvest and analyse first-of-a-kind data from the mooring arrays. The ongoing development work assimilates observations into the coupled ice-sheet-ocean models using the innovative ensemble Kalman filtering approach: These are the first steps towards an Antarctic ice-sheet reanalysis-style product that has not been attempted before. Datasets from OCEAN ICE include the comprehensive freshwater flux dataset, covering all solid, liquid, and vapour forms of mass loss, which has been distributed to modelling groups and is being incorporated into the final ice sheet projections. While these datasets have been produced before, this is the most internally consistent dataset based on earth observation data and state-of-the-art climate and ice-sheet models, including new processes for the first time. Alongside the whole dataset, we have also produced guidance for other modelling groups outside of OCEAN ICE to use these or similar datasets for the first fully comparable ice sheet and freshwater flux MIP, which will be integrated into current-generation Earth System Models as part of CMIP7. OCEAN ICE is also supporting the identification of feedbacks among processes, such as atmospheric rivers, sea ice, and the ice-sheet mass budget.