Science and Implementation Plan: Chapter 8

Implementation Plan

This revision of the WAIS Implementation Plan is based on deliberations of the September 1995 WAIS workshop. Participants assessed the status of the project by reviewing our accumulated knowledge relevant to the WAIS goal, identified future activities necessary to fulfill each objective, and selected the most urgent activities that would advance our progress toward these goals most rapidly. What made this discussion significant was that the areas of discussion were not the traditional scientific disciplines as used in the WAIS Science Plan, but the cross-cutting, multidisciplinary objectives of current behavior, physical controls/interactions/stability, and history. The fact that participants were able to rise above narrow disciplinary perspectives and discuss the status of WAIS, what activities still need to be conducted, and (perhaps most significantly) which of these are most urgent, represents the growing scientific maturity of WAIS.

Thirteen activities are identified as most urgent. Other than these items, no relative priority is implied by the position of any listed activity. These most urgent activities are described more fully in the following sections, and the Support Requirements Table (Section 8.7) includes estimates of the annual costs and logistics required to carry out these activities. This short-term focus is intended to maximize the plan's utility for both the science community-by describing the most urgently needed research proposals, and for the NSF Office of Polar Programs-by providing both science managers and logistic coordinators the most realistic assessments of near-term funding and logistic requirements. Thus, scientists contemplating involvement in WAIS are encouraged to adhere to the plan as much as possible.

As work proceeds, there will be a continuing need to reassess our state of knowledge as well as the necessary activities and those deemed most urgent. It is expected that the Implementation Plan will be updated annually at future WAIS workshops.


8.1.1. Current Behavior

From multiple eras of measurement programs stretching from WAIS back to the Ross Ice Shelf Geophysics and Glaciology Survey (RIGGS), it is now clear that the West Antarctic ice sheet drainage into the Ross Ice Shelf is experiencing a complex pattern of thickening and thinning of the ice (Figure 1). To varying degrees of spatial resolution, basic measurements of ice flow, ice thickness and accumulation have been made, and there is change underway nearly everywhere. These imbalances are most apparent on the ice streams where flow rates are highest. No single model matches this complex pattern of change.

The Ross Sea drainage area has also been the site of the most comprehensive study of the spatial pattern of accumulation rates. The results clearly demonstrate a spatial complexity that belies the simple parameterizations of precipitation (tied to lapse rate) used in most modern ice-sheet models (Figure 2). Meteorologists have developed the ability to derive moisture fluxes from measured synoptic data, enabling a powerful independent measure of the amount of mass delivered to the ice sheet through the atmosphere.

A new ice-sheet regime called an "ice plain" was discovered, where ice streams enter the Ross Ice Shelf. These broad, lightly grounded areas may be a natural result of till motion beneath the ice stream and are the site where the largest velocity change (15% in 11 years) has been recorded (possibly due to a recent increase in grounding).

The following questions point to important activities that need to occur to advance our knowledge of the current behavior of the West Antarctic ice sheet. Starred activities are judged to be most urgent and are discussed in more detail in the next section.

C1* What is the modern spatial distribution of and controls on mass input to the West Antarctic ice sheet?

C2* What is the modern configuration and behavior of the West Antarctic ice sheet; where is it changing and by how much?

C3* How accurately do the current generation of coupled atmosphere-ocean GCMs simulate the climate in the West Antarctic region?

C4 How should WAIS data sets be incorporated into a user-shared GIS?

C5 How is the iceberg flux changing?

C5 What is the height of the ice shelf around West Antarctica?

C6 What is the modern sub-ice-shelf mass budget?

8.1.2. Physical Controls, Interactions and Stability

The ice streams remain the key to West Antarctic behavior. Recent WAIS research has driven a progressive awareness that basal friction, reduced by lubrication, and side shear provide the major resistances to ice-stream flow, replacing the older notion that ice-shelf buttressing determined the fate of the ice sheet.

Basal lubrication is a difficult subject because it requires careful surface geophysical measurements and the drilling of kilometer-long holes through which direct measurements of the basal till are attempted while the ice is moving rapidly. Nevertheless, direct sampling of the subglacial regime has confirmed much of what was inferred from earlier surface seismic work. It is now known that ice at the base of ice stream B is clean, and drag there is concentrated in the sediment where interstitial water flow is very important. Borehole experiments have revealed that large, channeled water flow is rare or absent, and till sample analysis has shown that this material is extremely weak at the high water pressures measured on ice streams. The bed of ice stream C has not been sampled directly, but seismic surveys indicate that high basal shear is concentrated over only a small percentage of its bed.

The important role of ice-stream margins in resisting ice flow has presented glaciologists with a new challenge because the margins are heavily crevassed, endangering field parties. Misalignments of margins with basal topography are an expression of their ability to migrate and, in some cases, jump laterally. Strain softening and strain heating of the ice contained within the margin have been confirmed by vertical temperature profiles. These processes strongly affect the resistive capacity of the margins.

Satellite imagery has helped increase our knowledge of the West Antarctic ice streams not yet studied by field parties. Margins and onset areas of different ice streams display a variety of appearances and analysis of the image-derived velocity fields can even locate regions of probable high basal friction. Beyond the limits of the current ice sheet, marine seismic measurements have revealed broad furrows that indicate the course of the ice streams during the Last Glacial Maximum.

To increase our knowledge of the physical controls of the ice sheet and its stability, answers to the following questions need to be pursued.

P1* What determines the location of onset areas and are they fixed?

P2* What is the distribution of till, and what are its mechanical properties and its response to water pressure?

P3* What is the distribution of basal drag, and is it correlated with the subglacial geology?

P4* What determines the positions and strengths of ice-stream margins?

P5* How can ice-streams be modeled more realistically?

P6: How does velocity vary with depth near the ice bottom?

P7: What is the detailed structure of subglacial flutes (seen both on the Ross Sea bottom and under ice stream B)?

P8: What is the vertical temperature profile on an interstream ridge and in an ice-stream margin?

P9: Can basal water be imaged and what does it reveal about the subglacial hydrologic regime?

P10: What is the bed roughness at all scales?

P11: What is the water balance and till balance underneath an ice stream?

P12: What is the shape of an ice-stream margin with depth?

P13: What role does ice-shelf buttressing have on ice-stream behavior?

P14: What is the response behavior of ice rises and rumples to changes in the ice shelf?

P15: What controls the occurrence and disappearance of internal radar-reflecting layers?

P16: How does the warmer water in the deep ocean interact with the shelf water and affect sub-ice shelf mass balance?

P17: Are there key morphological features of the subglacial bed that characterize different modes of basal mechanics?

P18: Are there active subglacial volcanoes?

P19: What would be the East Antarctic response to a collapse, or partial collapse, of the West Antarctic ice sheet?

8.1.3. History

The West Antarctic ice sheet was much larger at least once in its history and has disappeared partially or completely at least once since it formed. These major fluctuations fit the theoretical model of Weertman, which is a major underpinning of the marine ice-sheet instability concept. The deglaciation history of the western Ross Sea is reasonably well known and it illustrates that the time of greatest ice-sheet extent probably preceded the Last Glacial Maximum. The retreat in this sector occurred separately in the discrete troughs filled by extensions of the present ice streams A, B and C. Ice flowed laterally during retreat, shifting to fill voids left by retreating ice streams. Ice-sheet and alpine-glacier moraines in the Executive Committee Range place elevation limits on the maximum thickness of the interior ice sheet and are consistent with a once-enlarged ice sheet stretching to the edge of the continental shelf.

Where the ice sheet presently exists, internal layers reveal historical behavior. Thinning at Byrd Station over the past 14,000 years has been relatively minor, and deposition on Siple Dome has been continuous for at least the past 10,000 years. Yet these internal layers revealed in radar soundings show contortions and relict disturbances that point to past ice streams flowing in places and along directions that differ from the modern positions and directions. These internal layers are not always seen, however. Satellite images contain an extensive array of flow-related features that underscores the temporal variability of flow patterns in West Antarctica.

The following questions define the research activities that are needed to learn essential facts about the history of the West Antarctic ice sheet.

H1* What is the climate history of West Antarctica and was there an ice sheet present there during the last interglacial?

H2* What is the deglaciation history in the eastern Ross Sea?

H3* What is the ice-surface elevation history revealed in the mountains within West Antarctica?

H4* What is the contemporary rate of relative sea level rise and does it help constrain the deglaciation history of West Antarctica?

H5* Do internal layers exist on other inter-ice-stream ridges and what do they reveal about the ice-sheet history?

H6: What are the leads and lags of West Antarctic ice sheet advance and retreat with global sea level and with glacial fluctuations in the Northern Hemisphere and in other parts of the Southern Hemisphere?

H7: Do additional subglacial sediment samples share similar mechanical and compositional properties with the samples underneath Upsteam B?

H8 What is the deglaciation style and chronology along the Bellingshausen and Amundsen coastlines?

H9: What is the history and character of interaction between the East and West Antarctic ice sheets?

H10: What is the significance of high-altitude glaciers on volcanoes in the Executive Committee Range?

H11: Can subglacial material be dated more precisely witn diatoms than has been accomplished to date?

H12: What is the cause and significance of the V-shaped feature on Roosevelt Island?

H13: Would meteorite collection in West Antarctica assist in determining West Antarctic evolution?


While all of the questions listed above are important and must be answered to fully attain the WAIS goals, those starred items comprise a more urgently needed subset. Each question is described below, with a fuller explanation of the particular science to be accomplished and a recommendation of how it could be accomplished. The Support Requirements Table summarizes the funding and logistic requirements.

C1* What is the modern spatial distribution of mass input to the West Antarctic ice sheet and what controls this pattern?

The West Antarctic ice sheet results from the accumulation of snow. Variations in net accumulation (the difference between precipitation and sublimation) contribute to the resulting pattern of flow. Meteorological techniques have been developed that calculate moisture flux from standard products available from the international weather centers. Thus, the annual and seasonal accumulation rates for sectors of West Antarctica can be calculated. In addition, the planned ice cores will yield records of snow accumulation, regional climate, globally mixed gases, and solar interactions. These data, when combined with the observations described below, will provide the basis for describing and understanding the spatial and temporal variations of precipitation, sublimation and temperature over the West Antarctic ice sheet. The El Ni–o-Southern Oscillation (ENSO) phenomenon is strongly and variably manifested over West Antarctica, and understanding how its variations arise on the synoptic and hemispheric scales is essential for interpreting the climate records from the planned deep ice cores (see H1), as well as for understanding how the ice-sheet mass input could change under altered boundary conditions.

To support the ice-core interpretation and the regional meteorology data base, the University of Wisconsin Antarctic Meteorological Research Center (AMRC) will continue to archive the Antarctic composite IR images, the National Meteorological Center Global Gridded Analysis, Antarctic station observations including radiosonde soundings, Advanced Very High Resolution Radiometer (AVHRR) data, and automatic weather station (AWS) data. The European Centre for Medium-range Weather Forecasts (ECMWF) daily output will need to be collected. The field operations will be the deployment of one or more AWS units each year for the next three years or more over West Antarctica. The first AWS unit will be installed at Siple Dome during the 1995-1996 field season. The Siple Dome AWS unit will measure the snow temperature profile to a depth of 10 meters and the snow accumulation at the surface as a function of time. In addition, the usual AWS measurements will be made of air temperature, relative humidity, wind speed, wind direction, vertical temperature difference in the air, and air pressure. The Byrd AWS unit will be continued and the eight-AWS-unit array on the slope between Byrd Station and the Siple Coast will be continued. Once a second site for ice-core drilling has been selected, AWS units will be installed at the site and at four locations 100 kilometers from the drilling site. These data collection activities are already funded and logistically supported by NSF-OPP. However, the required analysis efforts are new and will need funding, but do not involve field work.

C2* What is the modern configuration and behavior of the West Antarctic ice sheet; where is it changing and by how much?

Migration of ice-stream margins, shutdown of ice streams, changes in grounding-line position, and a discordance of flow bands and current ice-flow directions are all indications of the changes that are occurring in West Antarctica. Calculations of the rate of ice thickness change are usually non-zero. Added to this, numerous disintegrating ice shelves in the nearby Antarctic Peninsula emphasize the need for the establishment and maintenance of an effective, comprehensive and coordinated monitoring effort. To the greatest extent possible, WAIS should exploit current and future satellite sensors which routinely collect data over the Antarctic. Field and airborne measurements of ice elevation and ice thickness are needed, both as basic data for mass-balance calculations and for verification of change.

Satellites, in particular the Landsat series, have been used very effectively to document coastal conditions in the past. A continuation of this work is important, on a routine basis, as much of what is recognized as change depends entirely on the existence of an historical record. With a new generation of Landsat and SPOT spacecraft, and EOS imagers to be launched in 1998/99, monitoring activities that utilize imagery at the visible wavelengths should flourish. An entirely new aspect of this sort of activity was introduced with the advent of regular coverage of coastal Antarctica with satellite-based imaging radars. The European satellites ERS-1 and ERS-2, the Japanese satellite JERS-1, and the Canadian satellite Radarsat, when used with the new receiving station in McMurdo, provide the first chance to have scheduled high-resolution imagery that is unaffected by clouds. These imagers will greatly simplify the work required for routine coastal monitoring. The radar altimeters on ERS-1, ERS-2, and the past missions of Seasat and Geosat, should allow a reasonable monitoring of changing conditions on the large ice shelves, where low surface slopes simplify the interpretation of these data. Finally, the EOS laser altimeter will begin an era of substantially increased precision in measuring elevation changes across the entire Antarctic ice sheet. Many of the requisite remote-sensing activities are currently underway, funded by either the NSF, USGS or NASA. However, the repeat surveys are generally not supported and require specific funding for image purchase and analysis.

Radar soundings of ice thickness are logistically difficult to obtain, but are essential in mass balance assessment. The areas most in need of coverage are ice stream E, Pine Island and Thwaites Glaciers, and a repeat set of measurements across the grounding lines of ice streams AÐE and the ice plain of B. The Support Office for Aerogeophysical Research (SOAR) instrument suite is well suited to this data collection task by providing both precise surface elevations and ice thicknesses from a Twin Otter positioned accurately by GPS.

C3* How accurately do the current generation of coupled atmosphere-ocean GCMs simulate the climate in the West Antarctic region?

Atmospheric dynamics control snow accumulation rates over ice sheets. Simple thermal parameterizations cannot adequately predict the changes in accumulation rates that would result from shifts in the storm tracks in a greenhouse-gas-enhanced atmosphere. It is necessary to couple an ice-sheet model with an atmosphere General Circulation Model (GCM) in order to be able to predict changes in the Antarctic net accumulation. Predictive GCMs and ice-sheet models hold the promise of understanding the nature of the glacial-interglacial cycle, but such large-scale models need to be augmented by mesoscale models (see P5) and tested by collected data (see C1) to be most useful. Ice-sheet models forced by the GCM-generated net accumulation should provide a new ice topography as an updated boundary condition for a GCM, thus forming a feedback in a coupled ice-atmosphere system (see P5).

Currently, two modeling strategies exist for simulating atmospheric processes. Regional (or mesoscale) models are used for relatively short time integrations (a few days to approximately 1 week) to understand fine-scale details of atmospheric processes, such as evolution of cyclones and related synoptic processes. GCMs are used for longer term integrations of about a month or more with applications up to geologic time scales. Both modeling strategies should be employed in WAIS. Regional modeling efforts should be focused on the synoptic-scale environment, assessing the patterns of moisture transport on a case-study basis using data from available observation networks. These case studies would be used to refine the parameterization schemes in GCM simulations.

No field work is required for the modeling activities. This work will depend on refined GCMs with coupling of the atmosphere and ocean.

P1* What determines the location of onset areas and are they fixed?

The acceleration of slowly moving inland ice marks the initiation of an ice stream. Learning the reason for this phenomenon is crucial for understanding why ice streams occur and is centrally relevant in understanding why they persist or, in the case of ice stream C, stop. The hypothesis of geologic controls, such as a fault zone or enhanced geothermal heat flow, suggests a stagnant onset zone where either a shift in sediment properties or an increase in subglacial water determines the onset location. Competing hypotheses appeal to the extreme thinning that accompanies the accelerating flow or the transport of deforming subglacial till, both of which require some migration of the onset area.

The answer to this question requires a concerted field study of the onset process. An initial surface survey, guided by imagery, is already funded to identify the spatial pattern of acceleration. This will be completed in 1997. Subsequent field seasons will require more detailed surface deformation work, radar and seismic investigations in those regions where the coarse survey identifies onset begins. Finally, the direct sampling of the bed in areas both upstream and downstream of onset will determine the change in basal conditions that accompanies onset. These studies should include any physical characterization of the onset process that enables numerical simulation for numerical models.

P2* What is the distribution of till, and what are its mechanical properties and its response to water pressure?

Basal lubrication is the primary causative mechanism of ice-stream motion. To model ice-stream behavior and predict its time development in response to internal and external variables, the basal lubrication mechanism, which is composed of additive contributions from basal sliding and sub-sole till deformation, must be understood and quantitatively formulated. The chief ingredients of this formulation are the distribution of till over the bed, the source and transport controls on this distribution, the rheological properties of the till, and the basal-sliding law. The till thickness distribution can be measured in detailed seismic reflection profiles, the interpretation of which can be spot-checked in boreholes to the bottom. Via such boreholes, rheological properties of the till can be measured both in situ and in recovered core samples, as has been done on ice stream B at UpB. By basal measurements, sliding and till deformation can be measured and their contributions to basal lubrication, distinguished. Further, it is necessary to measure the basal shear stress, which enters into the sliding and rheological laws; this can best be done by laboratory creep tests on basal ice obtained by deep-core sampling in conjunction with basal shear-strain-rate measurements.

A crucial additional measurement is the basal water pressure and the closely related pore water pressure of the till and the ice overburden pressure, which have a strong effect on the strength (hence rheology) of the till, as shown by laboratory experiments on the till. Because of this effect, water pressure must be included in modeling ice-stream motion, which therefore requires a model of the basal water-conduit system in which the pressure is generated. To obtain the observational basis for constructing such a model, basal measurements that can constrain the system geometry are particularly important. Measurement of the basal melting rate, which provides the source term for water flow in the basal conduit system and the generation of basal water pressure, is also needed. In any model, the melting rate will be closely related to the vertical profile of temperature in the ice, which can be measured in boreholes. Sedimentological and paleontological studies of the till shed light on the bedrock sources of the till and the transport of the till in conjunction with ice-stream motion. Interpretive work should include formulation of basal-sliding and till-deformation laws, and relations governing basal water pressure and till generation and transport under the ice streams, suitable for use in ice-stream/ice-sheet models.

At a minimum, the above observations need to be made on an ice stream at two or three sites that are physically quite distinct, in order that the control-response relations among the several physical variables can be reasonably well revealed. Of greatest urgency for the immediate future are a second site on ice stream B, probably about 150 km upstream from UpB (already funded), and two sites on a second ice stream, either D or E, to test the generality of the conclusions from ice stream B and to extend the range of the physical conditions encountered. High-resolution seismic profiling to define the basal till distribution should be done in the region around each borehole site.

P3* What is the distribution of basal drag, and is it correlated with either the subglacial geology or the flow pattern of subglacial water?

To understand the interplay between interior ice which is "stuck" to the bed and the ice streams with their dramatic basal slippage, we must understand the distribution and causes of basal drag. Its source is the lubricating till that underlies the ice streams. These tills are thought to be derived from subglacial sedimentary units combining with subglacial meltwater. If both factors contribute to the mechanical behavior of the till, then basal drag should be partly controlled by the distribution of sedimentary basins and geothermal flux. In the limit, it is possible that subglacial geology dictates areas of low basal drag and therefore the location of the ice-stream onsets (see P1) and margins (see P4).

Such simple interpretations do not account for the subglacial water distribution driven by the coupled effects of surface and bed morphology or simple bed roughness. These contributors to basal drag almost certainly play a dominant role beneath the interior ice as well as for "sticky" spots on the ice streams. Ice stream C has shut down and remains nearly stagnant, even though high basal shear occurs over only a small percentage of its bed. To illuminate the differences (and similarities) between the evolution of interior ice and ice streams, we must correlate basal drag measurements gleaned from ice-sheet morphology and velocity observations with geophysical indications of subglacial geology and the flow pattern of subglacial water.

Significant efforts to correlate basal drag with geology and water flow are already underway. A 3-year program of aerogeophysics, begun in 1994, includes radar and laser investigations of surface and bed morphology and roughness, as well as gravity investigations of subglacial sedimentary units and magnetics studies of subglacial volcanism and the thermal structure of the crust. It is focused on the region extending from the ice divide above the catchment for ice stream D to ice stream D's grounding zone, including the interstream ridges between ice streams C and E. These data will be augmented by recently completed satellite measurements of D's velocity, work approved for the onset area of D (see P1), and new work recommended at the margins (see P4) and on the ice stream itself (see P2) to give an excellent picture of the basal drag distribution. Other existing grants are aimed at using these data to calculate the likely flow path of subglacial water under both C and D-currently only the upper portion of C is covered with the 5-km grid of surface elevation and ice thickness necessary for this work. These data, collected most efficiently by SOAR, should be collected over the remainder of C and also E.

P4* What determines the positions and strengths of ice-stream margins?

Ice-stream margins are major sites for control of ice-stream discharge. Moreover, the margins can migrate with time. For example, the southern margin to ice stream B2 controls much (50 to 100%, depending on the worker) of the driving force of the ice stream and is migrating so that the ice stream is becoming wider with time. Because the evidence for geologic control on margin position is inconclusive (see P3), we must assume that all margins are free to evolve and alter their influence on discharge of ice from the ice sheet. In some cases, imagery suggests that margins have experienced a nearly instantaneous lateral shift.

Three more margins should be studied. Each site entails a small field camp on the out-stream (safe) side of the margin. Work will entail a survey of the surface elevation and deformation fields, the collection of cores and measurement of the temperature profiles within the core holes. Science field teams will include glaciologists, geophysicists, seismologists, and drillers.

P5* How can the West Antarctic ice sheet and, in particular, the ice streams be modeled more realistically?

The collection of WAIS data must be aligned with parallel modeling projects that adequately incorporate the physics governing the system being studied. The validity of approximations and assumptions made which simplify model equations must be tested. There need to be models of the ice sheet itself, models of the surrounding oceans (see P15), and models of the atmosphere (see C3).

The most important aspect of the WAIS ice-sheet model is the basal boundary condition (see P2), yet it is the most difficult (and expensive) to observe. Thus, there needs to be close coordination between modelers and field scientists to optimize the return on focused studies of subglacial hydrology and sediment dynamics. These models should also strive to incorporate isostatic interaction of the ice with the lithosphere and interaction with a variable sea level.

The European Ice Sheet Modeling Initiative (EISMINT) has addressed each of the fundamental boundary conditions affecting the ice sheet as a whole, but has not concentrated on the peculiar complexities of marine ice sheets. Nevertheless, coordination of effort between the European modeling community and the U.S. modeling community could be extremely synergistic, including possible exchanges of computer-codes, modelers and workshops. Workshops on model intercomparisons and WAIS-specific model developments should be organized to accelerate model development and disseminate information and techniques to the various modeling communities.

Specific field work is not necessary, but models of the type necessary for WAIS require considerable computing resources. No single department, and few individual institutions, can support the level of hardware required to perform these modeling experiments. Collectively, computing power at the 1-YMP-equivalent processor full time is required. The processor should be piggybacked at a site where all the "extras'' (software licenses, maintenance, gurus, network connections) are already available. NASA/Goddard or NCAR are logical choices. Internet access for modelers at remote sites is, in general, sufficient for such modeling exercises.

H1* What is the climate history of the West Antarctic and was there an ice sheet present there during the last interglacial?

The WAISCORES element of WAIS seeks to recover and analyze two cores through the West Antarctic ice sheet, and to conduct related studies (ice-flow, geophysics, air-snow transfer, etc.) needed to interpret the cores. The main impetus is to obtain the history of climate change from this part of the world. This will improve our knowledge of the regional or global footprint of the rapid climate changes observed in Greenland ice cores, and of their timing and magnitude, information which is critical in predicting global climate change. The high-resolution nature of the available West Antarctic records will produce results not possible in East Antarctica. The dynamic nature of the West Antarctic ice sheet requires that we understand ice flow to interpret the cores; the climate-change records of the ice cores will provide a history of forcing and flow response needed to understand the ice sheet. Joint interpretation of the WAISCORES data with other WAIS results thus will improve understanding of the ice sheet and of climate change.

The WAISCORES coring is planned to begin at Siple Dome. Concurrently, site-selection activities will be completed at an inland site somewhere near the Ross/Pine Island Bay drainage divide. An aerogeophysical survey of the inland site has been completed, but a higher resolution surface-based geophysics program to measure detailed surface strain rates, accumulation and bed topography is also needed. After completion of coring activities at Siple Dome, coring is planned to begin at the inland site. The full program of the WAISCORES drilling effort is described in the WAISCORES plan prepared by the U.S. Ice Core Working Group.

H2* What is the deglaciation history in the eastern Ross Sea?

While the past extent and deglaciation history of the western Ross Sea is reasonably constrained, the deglaciation history of the eastern Ross Sea is virtually unknown. The nature and coarse timing of the retreat in the western Ross Sea have provided crucial indicators of the retreat's character and the possible condition of the till at retreat initiation. Lateral continuation of the geological and geophysical database into the eastern Ross Sea will permit evaluation of individual ice-stream histories. Core transects parallel to ice-stream flow will allow assessment of timing of deglaciation and rate of retreat in each paleo-ice stream, and hopefully will clarify which, if any, ice stream(s) acted as a "weak link(s)" to initiate retreat of the ice sheet occupying the Ross Sea. Finer resolution dating throughout the Ross Sea would address questions concerning linkages between deglaciations in the Northern Hemisphere and the Southern Hemisphere.

Additional swath bathymetry, which provides a footprint image of the seafloor, seismic data, longer cores and increased core coverage are required, especially in the eastern Ross Sea. The current knowledge of Ross Sea deglacial history permits selection of sites that will yield high-quality and extensive records of past ice activity. Higher resolution geological and geophysical tools, currently available, must be employed to further define the sedimentary boundaries between glacial environments.

H3* What is the ice-surface elevation history revealed in the mountains within West Antarctica?

Relatively little work has been devoted to establishing former levels and ages of the inland ice as measured on the nunataks and coastal mountains of West Antarctica. These data are essential for the numerical modeling of the ice sheet from its maximum to its present configuration. Prior work has been limited by the availability of datable material, but the development of cosmogenic radionucleide dating methods is opening new areas to study. The most useful and promising geographic areas for these studies presently appear to be (in priority order): the Reedy Glacier-Ice Stream A area of the north-facing Transantarctic Mountains; the Whitmore Mountains, where the East and West Antarctic ice sheets join; and the coastal mountains and nunataks of the Pine Island Bay-Thwaites Glacier area on the Marie Byrd Land coast.

Each area is an independent science package, and as such can be worked in any order based upon available logistics. The research in each area will require a party of 4-6 people working from a tent camp and using a combination of snowmobiles and a small helicopter. The inland camps can be put in by a C-130 aircraft. The coastal area could be researched either from a research ship like the Palmer, by helicopter, or by a tent camp equipped with snowmobiles and a small helicopter deployed from the ship, or with the same camp configuration put in by a C-130.

H4* What is the contemporary rate of relative sea-level rise and does it help constrain the deglaciation history of West Antarctica?

Detailed histories of isostatic rebound for large portions of the Laurentide and Fennoscandian post-glacial uplifts have placed constraints on Northern Hemisphere ice-sheet volume history and Earth rheology. In contrast, neither the history of uplift, nor contemporary rates of uplift, are known for West Antarctica. Relative sea-level (RSL) and GPS observations are needed to enable detailed modeling of ice-sheet collapse and ensuing isostatic rebound to place important constraints on the timing, location, and magnitude of West Antarctic ice-sheet mass change.

RSL observations include mapping and dating of relict shoreline features. These observations are limited to ice-free regions, but are essential for establishing a chronology of uplift in crucial areas such as the zone of grounding-line retreat along the western margin of the Ross Sea. In addition, lake coring that is undertaken primarily to determine past environmental conditions can also establish the transition of a lake basin from marine to fresh-water or hyper-saline conditions, and hence the time at which the basin became isolated from the ocean.

GPS observations can be obtained in the interior of Antarctica, where RSL techniques are not possible. GPS observations in the Transantarctic Mountains would test the hypothesis of a large, late collapse in the Ross Embayment and would complement RSL observations from Victoria Land, which are sensitive both to past ice mass changes in the Ross Embayment and in the adjacent regions of East Antarctica. GPS observations could also address tectonic questions, such as whether there is ongoing extension of West Antarctica, although the glacial rebound horizontal response is potentially significant, and would need to be considered.

Elevation data and fossil collection for deriving RSL profiles from emerged beaches, along with sediment cores in marine-transitional lakes, should be undertaken at various sites in the Ross Sea (Victoria Land and islands) and ranging eastward to the Antarctic Peninsula. Costs should be equally divided between strandline surveys and lake coring. Continuous GPS receiver operation over most or all of an Antarctic field season on an annual basis is needed to provide vertical rate accuracies sufficient to usefully discriminate between different deglaciation scenarios in a short (2-4 year) period of time. With semi-autonomous (solar- or wind-powered) GPS systems and data links for ongoing data and system monitoring, field requirements would consist of an initial deployment phase requiring several days' occupation of each site and subsequent visits for troubleshooting on an as-needed basis. Annual deployment and collection of the instrument packages may be required, depending on package design. Transportation by helicopter or fixed-wing aircraft is necessary, as appropriate. For five sites in the TAM, operating over 3 years (plus 1 year start-up) the cost is estimated to be $200k per year.

H5* Do internal layers exist on other interstream ridges and what do they reveal about the ice-sheet history?

Internal radar-reflecting layers in ice sheets are probably isochrones, most probably associated with volcanic fallout. The shapes of kinematically calculated deep isochrones can be compared with measured layers to deduce aspects of the history of the ice sheet. This history is important to deductions of the past and present stability of ice-sheet motion. Particular interest is attached to the interstream ridges. Work done on Siple Dome shows that this high dome has not changed in a major way during the past 10,000 years. Similar tests need to be conducted on lower ridges that are more prone to ice-stream migration and the ice-sheet thinning that probably occurred 14,000 years ago, associated with the global rise in sea level.

Four ridges need to be investigated with surface-based radar: ridge A/B; ridge B/C; the lower elevation portion of ridge C/D; and ridge D/E. The work would entail a small surface camp for one long or two short field seasons.


None of the critical research for WAIS requires major technical advances, although improvements on many fronts such as cosmogenic dating, finer resolution sonar, and more efficient drilling, obviously would benefit the research. The necessary capabilities are currently available in the United States. With the recent demonstration of ice-drilling capability for both recovery of core and bed access, as well as the emphasis on new aerogeophysical platforms, any part of the West Antarctic can be investigated either directly or remotely. Satellite and airborne remote-sensor data collected from current or planned instruments will expedite the collection of reconnaissance data and add to the analysis of field data. The laboratory capabilities also exist, as do the computers and modeling expertise to utilize them.


WAIS attempts to make efficient use of logistic support through coordination of its diverse field activities. Activities by different investigators, but in the same regions, will be executed together to the extent possible. Such coordination provides greater return for expensive logistic support such as remote field bases, Twin Otter aircraft or helicopters in regions far from McMurdo Station. This coordination is encouraged by the WAIS Working Group, but the Science Support Section of the National Science Foundation/Office of Polar Programs will ultimately determine the specific logistic support. OPP Program Managers and individual scientists will work in concert with the Science Support Section to realize as much logistic efficiency as possible in the execution of WAIS investigations.


The goal and objectives of WAIS fall well within the research interests of many other agencies; e.g., NASA, NOAA, DOE and USGS, which are active in global change and Antarctic studies. NASA already funds some WAIS-related research through its Radarsat and EOS programs. The WAIS Working Group will work with NSF/OPP to enlist the interest of these agencies in WAIS and to garner additional funding.

Further, many of the data sets are collected by the remote-sensing programs of other agencies. NASA supports the Landsat program while NOAA supports the AVHRR instruments. With the exception of the most recent Landsat data, these data are available at the cost of duplication.

Finally, the NSF/OPP maintains the Automatic Weather Station (AWS), Support Office for Aerogeophysical Research (SOAR), National Ice Core Laboratory (NICL) and Polar Ice Coring Office (PICO) facilities under separate funding, as well as the collection of AVHRR data at McMurdo and Palmer Stations. All of these facilities will be utilized in WAIS.


WAIS involves many investigators, large field campaigns, and substantial funding. In relevant disciplines where the population of currently active Antarctic investigators is small, there is opportunity for other interested scientists to become involved in an Antarctic research project with direct relevance to global concerns. Scientists currently involved in Antarctic research are encouraged to involve colleagues with relevant expertise in collaborative proposals.