US Global Ice Core Research Program
West Antarctica and Beyond

4.2.2 Long Paleoenvironmental Records: Greenland

Summit: The first field season of the GISP-2 deep core project in the summit region of the Greenland ice sheet was summer 1989. Deep drilling is projected for the summers 1990-1992. In collaboration with a multinational European project called GRIP two cores to bedrock will be obtained and analyzed independently. These records will constitute the longest time series available from ice sheets in the Northern Hemisphere (expected length >200,000 years). Frequent intercalibration of the analysis techniques will result in two independent records of paleoenvironmental conditions that are directly comparable and that will be interpreted jointly. The goal of the GISP-2 project is to obtain a long and detailed multiparameter record of environmental conditions in central Greenland with minimum complications from ice flow. The record will show natural variations with periods in the range of 1 to 105 years. The detailed multiparameter record will improve the interpretation of the rapid changes in climate and atmospheric composition observed in the Dye-3 core. It may also provide better understanding of the role of the North Atlantic, source area of the North Atlantic Deep Water, in the global climate system.

The GISP-2 project is funded by the NSF and a large group of investigators is measuring various core properties. Due to budgetary restrictions the analysis of a number of important core parameters could not yet be funded. It is important that the omissions in the core analysis be filled to gain the full scientific return from the drilling of this core. Bore hole studies over several seasons after completion of the drilling project should be encouraged. These will provide direct measurements of the differential movement of -the ice at different heights above bedrock, data invaluable for ice flow modelling.

North: After completion of the GISP-2 project and a first West Antarctic deep core, a deep core program in the northern part of Greenland is important to complement the data obtained from the Dye-3 core and expected from the summit cores. Comparison of results from the three sites will show the varying relative influence of the Arctic and the North Atlantic oceans on the local climate.

Within the framework of international collaboration between the United States and European countries plans should be made for airborne ice radar surveying and surface reconnaissance of the northern part of the Greenland ice sheet during the drilling of the Summit cores. This should identify sites at or near the flow divide with a relatively simple bedrock topography, temperatures low enough to preclude summer melting and an accumulation rate and ice thickness that provide good resolution in the upper part of the core as well as a long time record. It is desirable to continue US-European collaboration, established for GISP2/GRIP, in a North Greenland project.

Preliminary field operations for a drilling project in North Greenland could begin after completion of the GISP-2 drilling with deep drilling starting after the West Antarctic deep core. Participation in the North Greenland Project should be decided by review of individual P.I. research proposals submitted to NSF/DPP. The GISP-2 project could serve as an organizational model, to be amended later based on experience.

The GISP-2 and the North Greenland deep core projects should be complemented by intermediate and shallow drilling programs to obtain two or more cores down flow lines on either side of the divide towards the margin. These cores will provide information on glacial-interglacial changes in ice sheet configuration and ice flow. A continued US-European collaboration will make it possible to study simultaneously the eastern and the western Greenland drainage and thus to obtain rapidly a database useful for the interpretation of the paleoenvironmental records from the divide areas. Analysis of the intermediate and shallow cores should include most of the properties analyzed in the deep cores.

Long-range Antarctic and Arctic ice core research needs active participation by DPP and other NSF programs. The long lead times needed for proper site selection and the large logistics demands necessitate collection of a database for site selection and logistics planning for regular and systematic drilling beyond specific core projects already identified. DPP can facilitate and stimulate both in its contacts with the research community and its contractor PICO. The interdisciplinary focus of ice core research asks for continuous interaction with the various other fields of global change research to decide which questions are most important and can best be answered by ice core research. Drilling of cores so identified can then be initiated without a long delay for reconnaissance and without unforeseen logistics demands. Participation in the deep cores and other community-developed core projects should be decided by review of individual PI proposals. This should guarantee fair access to the projects for the whole glaciological research community.

Because the quality of the paleoenvironmental interpretation of ice core records depends on the comparison with other core properties and other core records, i.e. on the available ice core database, preliminary analysis of cores should be completed within two years of completion of the drilling. After that time the results should be made available to the community to aid in the interpretation of other records. Property data should be exchanged freely between participants in a single core analysis project.

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