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One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness parameters that are crucial for modelling ice flow and hence for predicting future ice loss and the ensuing sea level rise. Supported by the Scientific Committee on Antarctic Research (SCAR), the Bedmap3 Action Group aims not only to produce new gridded maps of ice thickness and bed topography for the international scientific community, but also to standardize and make available all the geophysical survey data points used in producing the Bedmap gridded products. Here, we document the survey data used in the latest iteration, Bedmap3, incorporating and adding to all of the datasets previously used for Bedmap1 and Bedmap2, including ice bed, surface and thickness point data from all Antarctic geophysical campaigns since the 1950s. More specifically, we describe the processes used to standardize and make these and future surveys and gridded datasets accessible under the Findable, Accessible, Interoperable, and Reusable (FAIR) data principles. With the goals of making the gridding process reproducible and allowing scientists to re-use the data freely for their own analysis, we introduce the new SCAR Bedmap Data Portal (https://bedmap.scar.org, last access: 1 March 2023) created to provide unprecedented open access to these important datasets through a web-map interface. We believe that this data release will be a valuable asset to Antarctic research and will greatly extend the life cycle of the data held within it. Data are available from the UK Polar Data Centre: https://data.bas.ac.uk (last access: 5 May 2023​​​​​​​). See the Data availability section for the complete list of datasets.

The legacy of the Scientific Committee on Antarctic Research’s (SCAR) PAIS strategic research programme includes not only breakthrough scientific discoveries, but it is also the story of a long-standing deep collaboration amongst different multi-disciplinary researchers from many nations, to share scientific infrastructure and data, facilities, and numerical models, in order to address high priority questions regarding the evolution and behaviour of the Antarctic ice sheets (AIS). The PAIS research philosophy is based on data-data and data-model integration and intercomparison, and the development of ‘ice-to-abyss’ data transects and paleo-environmental, extending from the ice sheet interior to the deep sea. PAIS strives to improve understanding of AIS dynamics and to reduce uncertainty in model simulations of future ice loss and global sea level change, by studying warm periods of the geological past that are relevant to future climate scenarios. The multi-disciplinary approach fostered by PAIS represents its greatest strength. Eight years after the start of this programme, PAIS achievements have been high-profile and impactful, both in terms of field campaigns that collected unique data sets and samples, and in terms of scientific advances concerning past AIS dynamics, that have measurably improved understanding of ice sheet sensitivity in response to global warming. Here we provide an overview and synthesis of the new knowledge generated by the PAIS Programme and its implications for anticipating and managing the impacts of global sea-level rise.

The past three decades have seen a sustained and coordinated effort to refine the seismic stratigraphic framework of the Antarctic margin that has underpinned the development of numerous geological drilling expeditions from the continental shelf and beyond. Integration of these offshore drilling datasets covering the Cenozoic era with Antarctic inland datasets, provides important constraints that allow us to understand the role of Antarctic tectonics, the Southern Ocean biosphere, and Cenozoic ice sheet dynamics and ice sheet–ocean interactions on global climate as a whole. These constraints are critical for improving the accuracy and precision of future projections of Antarctic ice sheet behaviour and changes in Southern Ocean circulation. Many of the recent advances in this field can be attributed to the community-driven approach of the Scientific Committee on Antarctic Research (SCAR) Past Antarctic Ice Sheet Dynamics (PAIS) research programme and its two key subcommittees: Paleoclimate Records from the Antarctic Margin and Southern Ocean (PRAMSO) and Palaeotopographic-Palaeobathymetric Reconstructions. Since 2012, these two PAIS subcommittees provided the forum to initiate, promote, coordinate and study scientific research drilling around the Antarctic margin and the Southern Ocean. Here we review the seismic stratigraphic margin architecture, climatic and glacial history of the Antarctic continent following the break-up of Gondwanaland in the Cretaceous, with a focus on records obtained since the implementation of PRAMSO. We also provide a forward-looking approach for future drilling proposals in frontier locations critically relevant for assessing future Antarctic ice sheet, climatic and oceanic change.

Analysis of multichannel seismic profiles collected on the continental rise off the Sabrina Coast, East Antarctica, has allowed the determination of the acoustic features that are indicative of major evolution steps of the East Antarctic Ice Sheet (EAIS) and highlights the role of meltwater that originated from Totten Glacier in shaping the margin architecture. The arrival of marine-terminating glaciers into the coastal region was recorded by an enhanced sediment input on the continental rise and the nucleation of channel-levees. Downslope sedimentary processes were dominant throughout the Late Cenozoic, testifying to the progressive growth of a highly dynamic, temperate ice sheet on the continent. The last evolutionary step marks the transition to when a full polar glacial regime occurred. The development of a prograding wedge with steeply dipping foresets on the continental shelf and slope exemplifies sedimentation at this time. Other sub-sea-floor observations indicate that downslope fluxes, triggered by glacial meltwater, were still able to deeply erode and deliver sediments to the rise area. This study's findings have led to the identification of expanded and well-preserved sedimentary successions, which we suggest should be considered as priority targets for future International Ocean Discovery Program deep drilling due to the sensitivity of the ice sheet in this area.

The continental slope and rise seaward of the Totten Glacier and the Sabrina Coast, East Antarctica features continental margin depositional systems with high sediment input and consistent along-slope current activity. Understanding their genesis is a necessary step in interpreting the paleoenvironmental records they contain. Geomorphic mapping using a systematic multibeam survey shows variations in the roles of downslope and along slope sediment transport influenced by broad-scale topography and oceanography. The study area contains two areas with distinct geomorphology. Canyons in the eastern part of the area have concave thalwegs, are linked to the shelf edge and upper slope and show signs of erosion and deposition along their beds suggesting cycles of activity controlled by climate cycles. Ridges between these canyons are asymmetric with crests close to the west bank of adjacent canyons and are mostly formed by westward advection of fine sediment lofted from turbidity currents and deposition of hemipelagic sediment. They can be thought of as giant levee deposits. The ridges in the western part of the area have more gently sloping eastern flanks and rise to shallower depths than those in the east. The major canyon in the western part of the area is unusual in having a convex thalweg; it is likely fed predominantly by mass movement from the flanks of the adjacent ridges with less sediment input from the shelf edge. The western ridges formed by accretion of suspended sediment moving along the margin as a broad plume in response to local oceanography supplemented with detritus originating from the Totten Glacier. This contrasts with interpretations of similar ridges described from other parts of Antarctica which emphasise sediment input from canyons immediately up-current. The overall geomorphology of the Sabrina Coast slope is part of a continuum of mixed contourite-turbidite systems identified on glaciated margins

The India-Antarctica separation is still an open problem due to the absence of critical geophysical data. So far no wide-angle data existed along the conjugate margins of East India and the Enderby Land off East Antarctica to define the position and composition of the continent-ocean boundary - a pre-requisite for any sound reconstruction. Furthermore, along both margins only old marine magnetic random track data are available for identifying seafloor spreading anomalies to describe the drift of both continents in the Cretaceous. The Kerguelen Plateau, located just north of the East Antarctica coast, however, has been drilled several times providing the only reliable age constraint on the formation of this huge magmatic plateau. In general, the poor information resulted a wide variety of kinematic models for the drift of the India. In the last years several newly acquired geophysical data provide new constraints on its drift. Two deep seismic sounding lines off Prydz Bay and across the Princess Elisabeth Trough show that oceanic crust is already present much closer to the present-day shelf break than previously known. Magnetic data acquired parallel to these lines provide excellent timing constraints for the initial breakup of India. Finally, marine magnetic data gathered in 2017 south of Sri Lanka indicate that here the oceanic crust is definitely younger than magnetic chron M0, questioning several kinematic models for the Indian Ocean. The latest results will be presented.

Gravity surveying is challenging in Antarctica because of its hostile environment and inaccessibility. Nevertheless, many ground-based, airborne, and shipborne gravity campaigns have been completed by the geophysical and geodetic communities since the 1980s. We present the first modern Antarctic-wide gravity data compilation derived from 13 million data points covering an area of 10 million km2, which corresponds to 73% coverage of the continent. The remove-compute-restore technique was applied for gridding, which facilitated leveling of the different gravity data sets with respect to an Earth gravity model derived from satellite data alone. The resulting free-air and Bouguer gravity anomaly grids of 10 km resolution are publicly available. These grids will enable new high-resolution combined Earth gravity models to be derived and represent a major step forward toward solving the geodetic polar data gap problem. They provide a new tool to investigate continental-scale lithospheric structure and geological evolution of Antarctica.

Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the horizon’ to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone.

Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the horizon’ to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i)Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access toAntarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone.

We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60� S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1) in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved datacoverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km3) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.

The ability of models to elucidate climate and ice sheet dynamics at the Eocene-Oligocene climate transition (34 Ma) is limited by a reliance on present-day topography as a boundary condition. We present a reconstruction of the Antarctic palaeotopography at the E-O boundary that restores sediment eroded from the continent. Estimates of sediment volume surrounding Antarctica constrain our restoration. Using data from coring and seismic imaging and allowing for a moderate biogenic fraction, weathering reactions and sediment porosity, a source volume of 5-13 million cubic km is thought to have been removed from an area of ca. 13 million square km. Changes to the East Antarctic landscape by local, regional and continental-scale ice have been estimated using an ice sheet and erosion model. Material is restored in response to basal conditions under a range of modelled ice-sheet configurations. These models can restore 3-4 million cubic km to East Antarctica. In West Antarctica, factors including the variable position of the grounding line make it impractical to use quantitative erosion models. Here we link geological evidence for known or suspected remnants of Eocene topography with our understanding of processes and patterns of erosion and deposition to drive construction of potential surfaces. There are several options for geologically reasonable surfaces that imply 5-10 million cubic km of eroded volume. The uncertainty in eroded volume is muted by the transformation to palaeo-elevation because isostatic compensation generally limits the change in average regional elevation to 15-20% of the thickness eroded.

Seismic stratigraphic studies and scientific drilling of the Antarctic continental margin have yielded clues to the evolution of Cenozoic climates, depositional paleoenvironments and paleoceanographic conditions. This paper draws on studies of the former Antarctic Offshore Stratigraphy Project and others to review the geomorphic and lithostratigraphic offshore features that give insights into the long-duration (m.y.) and short-term (k.y.) changes that document the great variability of Cenozoic Antarctic paleoenvironments. The lithologic drilling record documents non-glacial (pre-early Eocene) to full-glacial (late Pliocene to Holocene) times, and documents times of cyclic ice-sheet fluctuations at k.y. scales (early Miocene to Pliocene and Holocene). Times of significant change in types and/or amounts of glaciation are also seen in the offshore lithologic record (early Oligocene, mid-Miocene, early Pliocene). Seismic data illustrate large-scale geomorphic features that point to massive sediment erosion and dispersal by ice sheets and paleoceanographic processes (e.g. cross-shelf troughs, slope-fans, rise-drifts). The commonality of these features to East and West Antarctica since late Eocene time points to a continent that has been intermittently covered, partially to completely, by glaciers and ice sheets. The greatest advances in our understanding of paleoenvironments and the processes that control them have been achieved from scientific drilling, and future progress depends on a continuation of such drilling.

Recent geophysical surveys were designed to investigate the breakup process between India and East Antarctica and the effect of igneous activity on the formation of the Antarctic passive margin and the crust between the Kerguelen Plateau and Antarctica in the Princess Elizabeth Trough (PET). The Kerguelen Plateau marks one of the two most voluminous Large Igneous Provinces (LIP) in an oceanic setting and is attributed to a mantle hotspot emplaced at 120 Ma ago, about 15 m.y. after the previously suggested onset of seafloor spreading between India and Antarctica. Geophysical data analyses and modeling reveal a wide zone of highly extended continental crust on the Antarctic margin of Mac.Robertson Land. The partial continental affinity of the Southern Kerguelen Plateau, as indicated by earlier seismic data and ODP drill samples further north, continues to the southernmost limit of the plateau. Here, the continental crust must have been enormously thinned and fragmented as part of the rifting process between India and Antarctica. Ocean-bottom seismograph data indicate a narrow corridor of oceanic-type crust beneath the PET. Magmatic accretion to the crust is widely observed on both the plateau and the PET region.

In February-March 2007 PMGE, VNIIOkeangeologia and AWI conducted a joint geophysical survey in the area between the Prydz Bay and the southern Kerguelen Plateau (SKP) using two research vessels. Totally 5 000 km of MCS, gravity and magnetic profiles, 37 OBS records (along two N-S oriented MCS lines) and about 8000 km of detailed helicopter magnetic lines (in two local corridors centered on MCS-OBS profiles) have been acquired. Additionally two-ship (long-aperture) seismic experiment has been carried out along the 72.7E MCS-OBS line. Conducted investigations enabled definition crustal characteristics of this region, mapping principal tectonic provinces and features and development a seismic stratigraphy model. Major preliminary outcomes of the study are following: 1) the COB off Prydz Bay is marked by emplacements of mantle rocks into the lower crust (incomplete mantle unroofing) and is located 20-70 km southward of the prominent linear magnetic anomaly (Mac. Robertson Coast Anomaly); this anomaly might reflect a more active melt production during initial emplacement of the Kerguelen Plume into the oceanic lithosphere; 2) oceanic crust between 68E and 76E shows symmetric consequences of M-series magnetic anomalies with proposed extinct spreading centers implying paleoridge jumps; the SKP was probably isolated from India margin during this event and is underlain by extended continental crust; 3) flat-lying terrace with thickened (10-11 km) magmatic crust was recognized around the major morphological elevation of the SKP.

Accurately locating boundaries between continental and oceanic crust is topical in view of locating offshore boundaries relevant to margin formation models, plate kinematics, and frontier resource exploration. Although we disagree with Tikku and Direen's interpretations, the associated controversies reflect an absence of agreed-upon geophysical criteria for distinguishing stretched continental from oceanic crust, and a lack of samples from nonvolcanic margins.