ISAES ACE Sub-Committees/Science Community Promoted Sessions

4. Antarctic palaeotopographic reconstructions and feedbacks between topography, ice sheet and environmental evolution
(Convenors: Stewart Jamieson and Graeme Eagles)

Investigations of past Antarctic climate evolution benefit greatly from the integration of numerical models and geological evidence. However, these models currently lack a full set of realistic boundary conditions. Among these, the palaeotopography of Antarctica is key for understanding past ice sheet and climate interactions, as the nature and elevation of the ice sheet bed exerts a strong influence on its behaviour in response to more rapidly-changing forcing agents. The recognition that multi-scale climatic, tectonic, geophysical, and geomorphic evidence can be brought together in models to constrain continent-wide reconstructions of palaeotopography and palaeogeography has led to the development of the ACE/SCAR ANTscape project.

This session aims to identify, understand and quantify long-term changes to the topography of Antarctica and thereby contribute to the ANTscape objective of reconstructing palaeogeography at multiple timescales. Further, this session will discuss the importance of such changes for the evolution of ice sheets and the surrounding palaeoenvironment.

We invite contributions that: constrain and reconstruct palaeotopography on local, regional or continental scales; elucidate the feedbacks between long-term changes in topography, climate and ice sheet evolution in Antarctica; and reconstruct and visualise past Antarctic environments. We anticipate that this session will bring together contributors using modelling, visualisation and/or field-based approaches to gain clearer and more reliable conceptions of Antarctic palaeogeographic environments and of patterns in its long-term evolution and feedbacks with climate.

6. Antarctic subglacial lakes and continental-scale basal hydrology
(Convenors: Neil Ross, Mike Bentley and Slawek Tulaczyk)

More than 386 Antarctic subglacial lakes have now been identified. These lakes are believed to be: (i) important biological habitats; (ii) recorders of ice sheet history; and (iii) a key influence on ice sheet dynamics. Preparations for the exploration of subglacial lakes are now well advanced, with three major programmes (Lake Vostok, Lake Whillans and Lake Ellsworth) anticipating direct lake access within the next 2-3 years.

Parallel to this phase of planning, significant advances have been made in characterising Antarctic subglacial hydrological systems through the application of remote sensing and geophysical methods. The complexity and interconnectedness of these subglacial hydrological systems is now recognised, whilst observational evidence suggests a link between subglacial hydrological events and ice sheet dynamics.

We welcome submissions from any of the broad array of disciplines associated with the study of Antarctic subglacial hydrological systems. This session will focus not just on subglacial lake exploration, but also the complex interplay between subglacial hydrology and the overlying ice sheet. Suggested relevant topics include, but are not limited to:

- Biological, chemical and physical properties of subglacial water bodies and underlying sediments;

- Technologies and logistics for accessing, measuring and sampling subglacial lakes;

- Cleanliness and sterility protocols for accessing subglacial environments;

- The geomorphology and sedimentology of subglacial hydrological systems;

- Remote sensing and geophysical observations of subglacial hydrological systems;

- Modelling subglacial hydrology and its interaction with the overlying ice sheet.

9. Circum-Antarctic stratigraphic and paleobathymetric reconstructions for paleoclimate studies
(Convenors: Karsten Gohl, German Leitchenkov and Stuart Henrys)

The Antarctic continent and margin hold a remarkably wide range of archives recording past climate and tectonic events. To understand the feedbacks in this system the community needs to close the gap between regional seismic mapping, paleoenvironmental studies, and tectonic and sedimentary evolution. The CASP project (under SCAR-ACE) is an umbrella of regional stratigraphic mapping projects of the various Antarctic sectors with the aim to generate a unified circum-Antarctic stratigraphic and paleobathymetric grid series. Such a grid series sets boundary conditions for ocean circulation models, opening of ocean gateways, reconstruction of the Antarctic landscape, and global climate models using seismic reflection data and rock sample information as well as up-to-date plate-tectonic reconstructions.

We invite submissions on multidisciplinary studies focused on circum-Antarctic and regional seismic stratigraphy, paleoceanographic reconstructions, paleobathymetry modelling and other approaches with implications for paleo-current and paleoclimate feedbacks. In particular, contributions of recently acquired data and analyses are desired.

10. Evolution of life, environments and climates in Antarctica from deep time to the present
(Convenor: Jane Francis)

This session will cover the evolution of the Antarctic biosphere from any interval of the geological past to present day and including plants and animals from both marine and terrestrial environments. We welcome reconstructions of the environments in which they lived, based on a wide range of geological evidence such as sedimentology, ichnology, geochemistry, geomorphology and more. In addition, this session will include presentations about past climates of Antarctica and their influence on the biosphere. We welcome innovative interdisciplinary studies that highlight the unique polar environment.

15. Neogene climate evolution and ice sheet response, an Antarctic margin perspective
(Convenors: Richard Levy and Allan Ashworth)

Earth’s climate has evolved over the past 23 million years with significant cooling events at the Oligocene/Miocene boundary, Miocene climate transition, and late Pliocene and periods of peak warmth in the early-mid Miocene and early Pliocene. Response of the Antarctic cryosphere to these perturbations in global climate has largely been inferred from deep sea proxy-records. However, stratigraphic data from boreholes around the Antarctic margin and outcrop in ice-free regions on the continent provide direct evidence of past climatic conditions and provide proximal records to constrain far-field data. New results from offshore drilling by the Antarctic Geological Drilling Program (ANDRILL), Integrated Ocean Drilling Program (IODP), and Shaldril provide high-resolution records of environmental change through the Neogene and the Quaternary. Ongoing field studies of terrestrial outcrop and landforms continue to uncover key archives of physical and biotic response to past climate change. Development of new generation numerical climate and ice sheet/glacier models provide insight into driving mechanisms and offer platforms to test data-driven hypotheses. This session provides an opportunity to highlight the current state-of-understanding of Neogene and Quaternary climate in Antarctica and to reconcile records from terrestrial regions with sedimentary records of environmental change from the Antarctic continental margin.

17. New insights into the Cenozoic history of the Wilkes Land Antarctic Margin - consequences for biotic, oceanographic and climatic evolution
(Convenors: Carlota Escutia, Henk Brinkhuis, Robert Dunbar and Adam Klaus)

Antarctica has been glaciated since the early Oligocene. Over the past 34 Ma its ice sheets have fluctuated in size, responding to, and influencing global climatic conditions. Antarctic glacial variability has contributed to changing sea levels, paleoceanographic conditions, and biological evolution, among other processes. The extent and timing of fluctuations in Antarctic ice volume are still poorly known. In recent years, studies of long sedimentary sequences drilled in and around Antarctica combined with modeling have led to significant advances in the understanding of the evolution of the Antarctic continent (climate, tectonic, etc), notably at a regional level. A new series of sedimentary records was obtained recently during the Integrated Ocean Drilling Program (IODP) Expedition 318 to the Wilkes Land margin. This expedition is the first ocean drilling to take place in this region of the Antarctic continental shelf and rise. The sedimentary records obtained by this Expedition cover critical periods in the development of Earth’s climate extending from the Greenhouse to Icehouse transition to the Holocene following the last deglaciation. Combining these new records from the Wilkes Land margin with those from other regions around the Antarctic margin allow us to resolve sectoral response of the West and East Antarctic Ice Sheets and margins to climate change over the past ~45 Ma and serves as a guide to assessing future climate change more accurately.

This session is designed to investigate and share with the scientific community the preliminary results from IODP Expedition 318. This will necessarily include many orders and scales of variability of the Antarctic ice sheet, climate, paleoceanography, biota, and tectonics. We welcome abstracts dealing with all aspects of this research and any associated studies and all methodologies (e.g, geochemical, geophysical, paleomagnetical, stable isotope, paleontological, sedimentological, etc).

23. Quaternary history of the Antarctic Ice Sheet: A marine perspective
(Convenors: James Smith, Eugene Domack and Claus-Dieter Hillenbrand)

Ice sheet models require accurate geological data to constrain them and the Quaternary marine record represents one of the most detailed and complete archives of ice sheet variability in Antarctica. Not only can this data help to constrain and refine ice sheet models seeking to predict future changes but it also helps to define ice-sheet processes that are relevant on human time-scales. The Last Glacial Maximum (LGM) left a detailed imprint of former ice extent and behaviour in shelf sediments and geomorphology, yet the style and timing of deglaciation remains uncertain for many sectors of the ice sheet. Several studies suggest that the deglaciation of the East and West Antarctic ice sheets was asynchronous, with model reconstructions indicating that the major phase of deglaciation occurred during the Holocene. On glacial-interglacial time-scales, it has been suggested that the West Antarctic Ice Sheet may have undergone catastrophic change (collapse) on at least one occasion during the Quaternary, although the marine evidence for such an event is inconclusive.

The aim of this session is to draw together marine geological/geophysical evidence for ice sheet sensitivity including: offshore evidence for Quaternary deglaciations (specifically evidence for ice sheet collapse and post-LGM ice retreat histories), ice shelf history, palaeo-ice flow changes from marine sediment cores and geomorphology, records of palaeo sea-level as well as modelling ice sheet change(s). We encourage contributions from all sectors of Antarctic continental shelf, slope, rise and Southern Ocean relating to ice sheet variability. We also welcome papers documenting recent technological/methodological advances for dating marine sediments.

24. Quaternary history of the Antarctic Ice Sheet: a terrestrial perspective
(Convenors: Joanne Johnson, Chris Fogwill, Dominic Hodgson and Andrew Mackintosh)

Over the past two decades, satellite remote sensing of the surface elevation and physical properties of the Antarctic ice sheets has led to a revolution in our understanding. These observations have highlighted a variety of ice sheet processes operating at rates far higher than expected. These dynamic processes are not yet fully included in predictive models of future ice sheet and climate behaviour. The challenge for palaeoclimate research is to place these observations into a longer-term (millennial-scale) context, to produce ice sheet models that can reliably predict the future stability of the Antarctic ice sheets and the magnitude of associated sea level change. Palaeo-records of deglaciation in Antarctica provide important data for testing such models, but the wide range of records and chronological techniques used are not always well-integrated.

The aim of this session is therefore to bring together the broad range of terrestrial studies which aim to reconstruct the history of the Antarctic ice sheet during the Quaternary. This period covers several interglacial periods that were warmer than the present, and thus provides analogues for assessing the likely response of the ice sheet to future climatic warming. We welcome contributions from any sector of Antarctica, that combine palaeoenvironmental and geochronological reconstruction techniques, but particularly those that integrate data with ice sheet modelling. We encourage submissions related to refining geochronological techniques in this unique environment, and those that seek to relate ice sheet instability to melt water pulses and sea level change.

This activity is part of the Scientific Committee on Antarctic Research (SCAR)