pdf SCAR EXCOM 2019 Paper 6: Report from PAIS SRP

SCAR Executive Committee Meeting
30-31 July, Plovdiv, Bulgaria

SCAR EXCOM 2019 Paper 6: Report from PAIS SRP

Past Antarctic Ice Sheet Dynamics (PAIS), 2018-19 Report

Agenda Item: 4
Person Responsible: Tim Naish

Report Authors: Tim Naish (NZ) and Laura De Santis (Italy)

Summary

The Past Antarctic Ice Sheet (PAIS) programme aims to improve understanding of the sensitivity of East, West, and Antarctic Peninsula Ice Sheets to a broad range of climatic and oceanic conditions and to improve confidence in predictions of ice sheet and sea level response to future climate change and ocean warming.

PAIS has delivered above expectation with respect to the implementation plan, and is now completing final products, which are outlined further in this report. Following a very successful strategic planning workshop in Trieste, Italy, in 2017 the PAIS community have produced a strategic White Paper (http://www.scar-pais.org/index.php/documents/13-pais-conference-2017-white-paper/file) that identifies priorities for future research. The white paper recognises the importance of transdisciplinary approach incorporating geoscience, physical sciences and biological sciences in understanding and quantifying the Antarctic ice sheet contribution to past and future global sea-level change, from improved understanding of climate, ocean and solid Earth interactions and feedbacks with the ice.   It also recognizes the importance of understanding the global consequences and impacts of Antarctic change so that decision-makers can better anticipate and assess the risk in order to manage and adapt to sea-level rise and evaluate mitigation pathways. Consequently, the PAIS white paper has been influential in the development of a new SRP – Antarctic Ice Dynamics and Sea Level (AIDSL).

Since SCAR Delegates Meeting in 2018 at Davos, Switzerland, PAIS reports the following highlights.

1. High-profile scientific papers (9 of the 11 highlighted papers were published in Nature journals) and show:
   • New evidence for the (in)stability of the marine margins of East Antarctic Ice Sheet under 300-500ppm atmospheric CO₂
   • Antarctic futures under high and low emissions pathways and implications for global sea-level rise, ocean change and biological systems.
   • The importance of solid Earth responses and feedbacks in controlling ice sheet dynamics
   • A new integrated model of Antarctic ice sheet evolution over the last 50 million years reconciling the roles of orbital forcing and atmospheric carbon dioxide with implications for future change
   • A review of the complex processes that occur at the boundaries of ice sheets (bedrock, ocean and atmosphere) and integrated data-model approaches that need to be the focus of future research.

2. Two integrated ocean discovery programme (IODP) drilling expeditions successfully completed (valued at ~$60M USD) to the Amundsen and Scotia seas were co-ordinated and led by the PAIS community. The sediment cores will provide an unprecedented level of insight on how the marine-based sectors of the Antarctic ice sheet responded to climates and atmospheric CO₂ levels predicted for this century including model simulations of the possibility of a tipping point being crossed at about 2 degrees C of global warming (the Paris IPCC agreement’s Target) that could lead to irreversible ice sheet loss.

3. The PAIS community have been active in outreach, engagement and ECR development. A highlight has been the IODP-PAIS Antarctic marine sediment core school at the IODP Gulf Coast Repository at Texas A&M University in June which has co-funded 24 students and ECRs (12 non USA and 12 USA), to learn how to characterise, sample and interpret marine sediment cores form the Antarctic margin.