Conditions in the subsurface of ice sheet outlet glaciers influence the rate and timing of grounding line retreat, exerting a fundamental control on Antarctic ice sheet response to climate forcing, and hence ice loss [1].
Subglacial conditions determine the basal friction that influences the relative contributions of basal sliding and sediment deformation to overall ice flow. Such conditions also impact the production of basal meltwater and its distribution via subglacial hydrology systems, and how basal heat sources, including geothermal heat flow, modulate ice dynamics.
The ice-bedrock interface zone (IBIZ) conditions and processes are particularly critical for major outlet glaciers of Antarctica’s ice sheets, especially those situated on the margins of deep basins, where ice extends well below present day sea level [2]. Many such locations are changing rapidly and vulnerable to further retreat under a warming climate. Despite their importance, subglacial environments remain among the least understood components of pan-Antarctic ice sheet systems. On-ground observations are currently sparse, but recent technology advances (e.g. improved remote power and data telemetry), and computational innovations will drive a step change in knowledge.
A Working Group (WG) focused on Antarctic subglacial environments is therefore urgently needed. This will bring together cutting-edge observational glacier geophysics [2,3,4,5,6] with new modelling strategies [7,8,9], including through novel data assimilation and machine learning methods. The WG will also link to researchers in glacier hydrology, geodesy and geology. By assessing where uncertainties in subglacial conditions have a pivotal impact, the WG will provide a quantitative basis for targeted field campaigns, improve process-based understanding, and hence achieve (in improved ice sheet models) a realistic coupling between basal processes and large-scale ice dynamics.
This WG aligns directly with the Antarctica InSync Theme III: Melting ice sheets and ice shelves and coastal impacts, with a focus on the Land/Ice Sheet area, connecting with Theme I: Southern Ocean and Antarctic heat, freshwater (etc). Understanding the physical controls on glacier motion and retreat is essential for improving projections of rapid ice loss. Quantifying the role of basal sliding, subglacial hydrology, and geothermal heat flow will enable better representation of ice-bed feedbacks in the next generation of coupled ice sheet-Earth system models. These feedbacks determine the rate of inland ice discharge to the ocean, and the potential for large-scale, rapid retreat under certain basal conditions.
Beyond advancing process understanding, the WG would also serve as a bridge between observational, data science, and modelling communities; supporting field-measurement standards, interoperability, and open sharing of subglacial data products. It will coordinate knowledge-sharing frameworks that are usable by the modelling community, particularly during the period of preparation for the Ice Sheet Model Intercomparison Project for CMIP7 (ISMIP7). Through this coordination, the WG will strengthen the international community’s capacity to predict how Antarctic glaciers will evolve under future climate scenarios, hence contributing to improved predictions of the pace and magnitude of Antarctica’s contribution to sea level rise, and of freshwater inputs to the Southern Ocean
The overarching aim is to improve knowledge of the subglacial environment, particularly focussing on vulnerable Antarctic glaciers, and how processes in the ice-bed interface influence ice dynamics. The WG will collaboratively coordinate new on-ground data collection, guided by modelling, that will result in important new knowledge of the subglacial environment, ultimately leading to better prediction of ice loss through key Antarctic outlet glaciers.
The scientific objectives of the WG address these key questions:
The coordination objectives will include:
The sampling approach has two tiers.
a) Basic instrumentation to be installed and surveys to be carried out on many outlet glaciers.
The aim is to capture essential geometry, englacial and subglacial structure and processes (including seasonal changes).
The use of relatively light logistics will enable many sites to be instrumented.
b) Detailed instrumentation and surveys, co-developing or aligning with other InSync ‘super-site’instrumentation as appropriate.
The aim is to (in addition to aims addressed using the basic instrumentation) inform firn variability in the context of mass balance calculations, subsurface hydrology and basal properties, and glacier processes, which will support activities under Theme 3 Knowledge GapKP3, and link strongly to Theme 7.
Target locations for better constraints of structure and process within outlet glacier systems will berefined and optimised using ice sheet modelling.
Scientific outcomes and deliverables will include:
A. Comprehensive mapping of fields in vulnerable glacier catchments within West and East Antarctica, provided on standard grids for use in ice sheet modelling and other activities. Some fields may have a temporal component, as appropriate. Fields include, but are not limited to, those related to:
B. Process-based understanding of the influence of subglacial conditions and climate forcing on basal ice motion, incorporating constraints from field observations, innovative AI-enabled analyses, and computer modelling.
C. Scientific publications
D. Contribution to ongoing efforts within SCAR SRP INSTANT (e.g. Theme 2 on Solid Earth-Ice Interactions and subcommittees on Antarctic Geothermal Heat Flow and Antarctic Geological Boundary Conditions)
E. Expand capacity by engaging PhD students, including through fieldwork where possible and through development and application of geophysical data analysis techniques and ice sheet modelling, supported by Team members who have strong track records in mentoring students to deliver novel scientific advances.
F. The above outcomes achieved through an enhanced, inclusive and collegial research culture, with active involvement of early-career researchers and many nations pro-actively encouraged [10].
| Timeframe | Task |
|---|---|
| Anticipated timeline and ideas | |
| March-July 2026 | Assembly of core team and development of international mailing list |
| e.g. EGU 2026 (May) and/or SCAR OSC 2026 (August) | Splinter meetings at major international conferences |
| by late 2026 | Development of standardised protocols for data collection, linking to ‘super-site’ protocols |
| 2027 | Publish as a White Paper or an interdisciplinary methods/concept paper for a Q1 journal |
Development of policy recommendations pipeline and documentation, linking to InSync knowledge translation |
|
This WG will be embedded within Theme III: Melting ice sheets and ice shelves and coastal impacts, linking strongly to the heat and freshwater components of Theme 1: Southern Ocean and Antarctic heat, freshwater, carbon and other elements cycles and their response to climate change. Outcomes from this WG will also inform Theme II (Rapid sea ice decline and its causes and consequences) and Theme VII (Variability, extremes, and tipping points in a changing climate), and we will work closely across InSync themes and partners to ensure that new knowledge is translated into outcomes that benefit end users.
We will align with major international efforts to ensure our work contributes to, and benefits from, other initiatives in subglacial processes, glacier dynamics, and ice sheet change. Activities will include:
We will collaborate closely with existing initiatives, including:
