pdf SCAR XXXVI Paper 31: Final Report of SRP PAIS (Past Antarctic Ice Sheet Dynamics)

SCAR XXXVI Delegates Meeting, Online, 16-25 March 2021

SCAR XXXVI Paper 31: Final Report of SRP PAIS (Past Antarctic Ice Sheet Dynamics)

Agenda Item: 16.4
Person Responsible: Laura De Santis

Authors: Laura De Santis (Italy), Tim Naish (New Zealand), with the collaboration of the PAIS steering committee

Introduction/background to the programme

The Past Antarctic Ice Sheet (PAIS) program’s aim is to provide geological and ice core evidence of Antarctic Ice Sheet response to a broad range of past climatic and oceanic conditions. That evidence is used to constrain paleo-simulations of regional Antarctic climate, ice sheet dynamics and sea-level models, as well as to improve the physics of climate and ice sheet models used in projections. Improved representation of processes within models has to narrower uncertainties in future Antarctic Ice Sheet contribution to global sea level changes in response to on-going and projected global climate change. PAIS has delivered above expectation with respect to the implementation plan developed 8 years ago, and is now completing final products. Extensive information will be available in book “Antarctic Ice Sheet evolution”
(publication planned in 2021, ANNEX A). The book is the product of a large PAIS community’s effort and represents a comprehensive synthesis of the current knowledge of Past Antarctic Ice Sheet dynamics, the legacy from previous SCAR programs, and of challenges for the future.

Major achievements and legacies

PAIS has coordinated the scientific community to share ideas, integrate multi-disciplinary knowledge, produce a large amount of high-impact scientific publications, to submit innovative international scientific proposals, and facilitate large international research consortia (e.g. IODP). PAIS catalysed the interest and facilitated the cooperation from other scientific programs and organizations by demonstrating the advantages of optimizing the use of research infrastructures and tools and of multidisciplinary teamwork. The main scientific achievements have progressed understanding of the complexity of the Antarctic ice sheet sub-glacial, ice proximal environments and distal environmental response to past global climate changes at different time scales over the past 34 Million years and at higher atmospheric CO2 levels. The PAIS Programme outputs are many, diverse and span: (i) the production of high-impact scientific publications in the world’s leading journals (ii) contributions to IPCC reports, Antarctic Treaty lectures and papers, and contributions to other international policy fora, (iii) building multi-disciplinary collaboration hosting ground-breaking community-driven international conferences (e.g. Trieste 2017), (iii) supporting student and ECR summer schools and training courses, (iv) leveraging more than USD $100M for international consortia to undertake geological drilling on the Antarctic margin, and (v) development a new generation of Antarctic ice sheet models for improved future projections of ice mass change and sea-level rise. We list below areas of major contribution:

• Fundamental new insights in Antarctic Ice Sheet sensitivity during past high-CO2 worlds and its contribution to global sea-level change.
• New knowledge on the extent and nature of major Antarctic glaciations
• Importance of evolving topography, bathymetry, erosion and pinning points in ice sheet dynamics
• Reconstructions of Southern Ocean sea and air surface temperature gradients and implications for polar amplification
• First geological evidence of ocean forcing and marine ice sheet instability
• Improved temporal and spatial patterns of AIS retreat and its contribution to rapid sea-level rise during global Melt-Water Pulse 1A
• A better understanding of ice-sheet-ocean interactions
• Co-produced with SERCE, fundamental insights into Antarctic ice-Earth interactions and their influence on regional sea-level variability and Antarctic Ice Sheet dynamics
• Improved interpretation of subglacial processes from mapping the seabed
• Paleo-data calibrated ice sheets models provide revised global sea-level predictions for IPCC scenarios.

Finally, as PAIS evolved it became more transdisciplinary working with solid Earth geodynamicists, oceanographers, climate scientists and a modellers. This lead to the development of a white paper that reflected a convergence of scientific interest across SCAR’s science groups on improving the understanding of Antarctica’s dynamic ice sheet contribution to global sea-level rise and lead to the development of the multi-disciplinary INSTANT Programme.

Final procedural recommendations to Delegates

SCAR continues to face some organisational challenges within its Science Groups. There is a high degree of fragmentation that leads to some inefficiencies and overlap of effort and capabilities. The SRP’s have proven instrumental in helping co-ordinate and focus SCAR capabilities on high-priority scientific issues, such as those outlined in the SCAR Horizon Scan. Future SRP’s need to build strong links with action and expert groups in SCAR (some rationalisation is still required), as well as external partners to ensure SCAR’s scientific capability is most effectively contributing to issues of global importance.