US Global Ice Core Research Program
West Antarctica and Beyond

4.3 Complementary Studies

The plans for ice core research presented above focus on ice core studies. Yet the discussion shows that selecting a good site to obtain a long paleoenvironmental record alone requires the collaboration of at least three different glaciology fields. Ice radar sounding of surface and bed topography and of internal layering and surface studies of accumulation, strain, and temperature should be distilled by ice flow modeling into a site choice. Involvement of several other disciplines and specialties is needed if the ice core records are to be exploited to the full potential of their paleoenvironmental information. Such involvement should be stimulated by multidisciplinary workshops and by making ice core data available via the World Data Center for cross-correlation with other paleoenvironmental records and joint interpretation. Collaboration is needed with, e.g. atmospheric scientists, oceanographers, geologists, and modelers.

4.3.1 Atmospheric Sciences:

All constituents found in ice cores originally came from the atmosphere. The amounts of these constituents in the core are dependent upon emissions at the sources, atmospheric transport from source regions to the glaciers, and deposition onto the surface. Changes that occur after deposition are also important.

Reconstruction of global climate and environmental conditions in the past from the ice core record requires that we understand each of these steps. In order to gain this understanding we must determine the present conditions and processes. Data on atmospheric emissions world-wide are available from numerous studies and should be collected. Atmospheric circulation patterns that affect the ice coring site should be determined to identify the most important source regions and transport pathways. Measurements of airborne concentrations and deposition rates of chemical species on a year-round basis must be made to define the atmosphere-to-snow transfer processes specific to the site of interest. These measurements should include air sampling as well as collection of fresh snow, older surface snow, and snowpit samples for detailed analysis. Year-round meteorological data at the site must be collected to define these transfer processes. Finally, processes that may redistribute constituents in the snowpack, such as meltwater percolation and diffusion of gases, should be studied at the ice coring site. Interpretation of changes in aerosol content and changes in the concentration of radiatively active gases in air trapped in the core in terms of their influence on global climate needs further study. Specifically, we need to determine the effect that an increase in the atmospheric concentrations of cloud condensation nuclei, indicated by increased sulfate concentrations in ice from glacial periods, has on cloud albedo and cloud distribution.

4.3.2 Oceanography:

Detailed correlation and interpretation of ice core and deep sea sediment records will reveal the way in which climatic and atmospheric changes express themselves in the two records.

Ocean sediment cores around Antarctica can provide a record of past fluctuations in sea ice -extent and ice discharge. Of special interest are indications of patterns of periodically increased discharge as reported from Indian Ocean cores, and the areal extent of such patterns. If episodic discharge were documented, it would have major consequences for our understanding and modeling of mass balance, ice flow and ice sheet shape.

4.3.3 Terrestrial Records:

Especially at lower latitudes it- may be possible to study pollen and other paleoindicators both in the ice and in deposits such as lake sediments, peat bogs, and loess. This can provide a very reliable way to correlate ice core records with other terrestrial paleoenvironmental records. If time series from ice cores can be correlated with radiocarbon dated records from other nearby environments then ice core chronologies can be improved. Involvement of e.g. palynologists and limnologists in certain parts of the ice core paleoenvironmental project should be stimulated.

4.3.4 Modeling:

The interaction between atmospheric climate, ocean circulation, ice sheet size and flow, and biospheric activity, and the effect of the different response times of these systems on global change need to be determined. Ice core data can make a significant contribution to the required database. Regular interaction with modelers of climate and ocean circulation is needed for an efficient use of ice core paleoenvironmental data in testing atmospheric and oceanic global circulation models. Interaction will also help identify for the ice core research community questions and modeling uncertainties that need to be eliminated by new or better paleoenvironmental data.

4.4 Summary

US ice core research can make important -contributions to our understanding of global change. A long-range ice core research plan for the next decade comprises:

· a deep core in West Antarctica; drilling to start around 1994-95,
· at least two intermediate and several shallow cores in West Antarctica,
· a second deep core and additional intermediate and shallow cores in Antarctica after completion of the drilling of the first deep core,
· one deep and several intermediate and shallow cores in Greenland after completion of GISP-2 drilling, and
· coordinated retrieval and analysis of other polar and lower latitude cores.

None of the actual cores are identified in this plan because W the available data are insufficient for a proper site selection, and (ii) due to rapid progress in global change research a site selected now, based on today's scientific questions may no longer be the most desirable site in two or three years when final site selection is made. For the first (West Antarctic) deep core site selection is focused on the cross hatched divide area in Appendix D. 

NSF/DPP should provide for two key ingredients for the successful realization of the plan, namely accumulation of a database on potential drill site areas that will allow selection of a drill site without additional delay for field surveys, and a logistics and drilling operation that can support ice core drilling in the Arctic, the Antarctic, and at lower latitudes and produce good quality cores to bedrock independent of the ice thickness. In addition DPP will need the funds to support the multiparameter laboratory analyses that retrieve the paleoenvironmental information from the ice cores.

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