Constraining Antarctica’s role in global sea-level rise is a key challenge. Anthropogenic warming drives ice-sheet mass loss, while a warmer atmosphere can also transport more moisture, leading to an increase in clouds and snowfall. Changes in atmospheric dynamics impact extreme weather events, such as Atmospheric Rivers, which also contribute to the mass balance (Wille et al., 2025). Additional accumulation partly offsets sea-level rise by enhancing Antarctica’s surface mass balance (SMB). The balance between these opposing processes remains poorly quantified.
Past observations are sparse: ice cores provide localized records, while satellites offer only recent coverage (Eisen et al., 2008). Climate models diverge due to poorly constrained processes such as atmospheric circulation, moisture transport, and cloud physics. Future projections remain uncertain, with contrasting signals across regions (e.g. Seroussi et al., 2024). Together, these gaps hinder robust estimates of Antarctica’s past, present, and future SMB trends and radiation balance. This underscores the large uncertainties in reconstructions and projections, and highlights the need to better understand Antarctic snow accumulation and atmospheric processes.
This Working Group will address these challenges, aligned with the Antarctica InSync priorities of integrating data and models, linking past and present, and improving future projections. As part of Theme III Melting ice sheets and ice shelves and coastal impacts, we will unite modelers and observational experts to synthesize diverse datasets, reconcile regional and continental perspectives, and reduce uncertainties in Antarctica’s sea-level mitigation potential. Such integration is essential to strengthen global radiation and sea-level rise assessments and provide knowledge critical for adaptation strategies.
Surface mass balance is a crucial factor in determining the stability of the Greenland and Antarctic Ice Sheets and their contribution to global sea-level rise. Even minor changes in SMB, which results from a complex interplay between atmospheric and surface processes like, precipitation, melt, sublimation, evaporation, and wind redistribution, can have significant impacts on the overall mass balance of these vast ice bodies, particularly in the context of a warming climate where precipitation patterns and melting rates are shifting.
For the Antarctic Ice Sheet, SMB is central to predicting future sea-level contributions and understanding how atmospheric dynamics and polar ice respond to climate variations. Accurate and continuous monitoring of SMB and driving processes is especially vital in remote regions with limited observational coverage. The Antarctic Ice Sheet is experiencing regionally variable changes, with some areas like West Antarctica and the Antarctic Peninsula already contributing to sea-level rise, while parts of East Antarctica show large variability and less certain trends, potentially increasing more mass than losing (e.g. Medley and Thomas, 2019; Eswaran et al., 2024; Wang et al., 2025). The frequency of extreme weather events might increase with a changing climate, impacting SMB on different spatial and temporal scales. Reliable reconstructions of accumulation and SMB over recent centuries are required to identify significant trends and enable robust projections of ice-sheet behavior as the climate continues to warm.
The newly proposed working group originates from Theme III Melting ice sheets and ice shelves and coastal impacts, but is designed to work across multiple themes. By addressing the questions outlined below, the group aims to advance understanding of past, present and future SMB changes driven by processes at the atmosphere-ice interface, within the firn, and through their influence on ice dynamics under a changing climate. The working group will further support improved temporal observations and modelling, thereby contributing to more robust predictions of the Antarctic Ice Sheet’s evolution and its contribution to global sea-level rise.
The working group will link distributed efforts by partners to determine SMB and thus allow
The working group will build on established methods for determining the surface mass balance (Eisen et al., 2008) and atmospheric observations (Lenaerts et al., 2019), but also include new technologies. In addition to point measurements of recent mass balance, time series over the last decades to centuries and millenia shall be reconstructed (e.g. from firn and ice cores) to understand the spatio-temporal variation of SMB, atmospheric composition and physical properties (e.g. temperature). Overall, the WG’s approach foresees to
| Timeframe | Task |
|---|---|
| Forming of core team until the end of 2025 | |
| Create an international mailing list of interested people until the end of 2025 | |
| Contribute to white paper/science plan of Theme III | |
| First international online workshop in first half of 2026 |
|
| In-person workshop/pop-up event at EGU 2026 or SCAR 2026 | |
| Second international online workshop in the fall of 2026 | |
| Establish standard variables and procedures for data acquisition prior to the Antarctica InSync fieldwork phase | |
| Internationally synchronized field campaigns between 2027 and 2029 across Antarctica |
This working group will be embedded in the Theme III Melting ice sheets and ice shelves and coastal impacts and will provide a paleo perspective on the SMB history of the Antarctic Ice Sheet. Moreover, we will closely collaborate with Theme VI “Aerosol-cloud interactions and radiative feedbacks” and the to-be-proposed Theme VII (working title “Extremes and Variability in a Changing Antarctica: Surface Mass Balance, Global Sea Level, and Water Cycle Changes”) as well as other relevant Themes and WGs.
Collaboration with SCAR INSTANT, SCAR ISMASS, SCAR-COMNAP RINGS. More specifically:
