ACE LGM/deglacial/Holocene Subcommittee

LGM-Holocene ACE subcommittee

Rationale:

The ice sheets of Antarctica were so much larger at the last glacial maximum (LGM, ~21,000 years) than today that global sea level dropped by around 20 m. The ice sheets at the LGM left a wealth of geological data, which can be used to constrain, validate and test numerical ice-sheet/climate models. Such work is critical to evaluating the evolution and stability of the present ice sheet. There are many questions to be answered with respect to the ice sheet configuration and flow at and after the LGM. The keys to answering the questions are (1) to enhance the sophistication of the models, and (2) to integrate geological data on past ice sheet and climate conditions with model output. The LGM-Holocene sub-committee will facilitate the co-ordination of research agendas in the following areas:

Numerical modelling of the Antarctic ice sheet with special application to the causes of grounding-line evolution during deglaciation.
The use of Earth-System models (in particular, coupled ocean-atmosphere GCMs) to understand climate change in the circum-Antarctic region from the LGM onwards, and the implications of these changes for the ice sheet.
The integration of the on-shore and off-shore geomorphological records of ice thinning and grounding-line retreat.
The integration of long-term sea-level records with inverse geophysical modelling to constrain mass loss from Antarctica.
The development of high-resolution palaeo-climate records from ice cores and deep-sea cores from the Southern Ocean, and the development of a consistent chronology to link individual records.

Focus:

The sub-committee will focus attention on the following open research questions: Has grounding-line retreat stopped? Can present-day changes be attributed to on-going retreat? How synchronous was deglaciation in the various sectors of the ice sheet? To what extent does the geomorphology reflect local rather than regional effects? What caused deglaciation? Can high-resolution chronologies be used to distinguish between the effects of sea-level rise and accumulation-rate change? What is the role of ice streams in controlling the rate of grounding-line retreat and volume loss? To what extent are ice streams transients features within the ice sheet and what are the controls on their long-term dynamics? What was the contribution of the ice sheet to eustatic sea-level rise and how was this contribution distributed spatially and temporally?

The sub-committee will convene dedicated sessions at relevant international scientific conferences such as the AGU, EGU, INQUA and IGS; making research grant proposals to the relevant national funding agencies with particular reference to the forthcoming IPY; and jointly co-writing a chapter reviewing modelling and observational literature for the LGM-Holocene as part of a dedicated ACE edited volume. The sub-committee will meet occasionally, primarily during larger international conferences and will seek funds from ACE itself to facilitate this.

The sub-committee as expertise in: the numerical modelling of ice sheets and palaeo-climate; ice and deep-sea sediment core records; on-shore and off-shore geomorphology; and sea-level records and modelling.

Committee Membership:

Tony Payne (chair, UK); Philippe Huybrechts (Belgium); Catherine Ritz (France); David Pollard (US); Colm O'Cofaigh (UK); Mike Bentley (UK); Howard Conway (US); Eric Wolff (UK); Glenn Milne (UK); Rob Dunbar (US); Robert Larter (UK)