US Global Ice Core Research Program
West Antarctica and Beyond

4.2 Global Array of Ice Cores

Long ice core records (>105 years) are limited to the polar regions. Obtaining a long core requires multi-season drilling and major logistics operations. To optimize the scientific return on such a large investment in time and money, the drill site has to be chosen carefully based on surface accumulation rates, firnification conditions, surface and bedrock topography, and ice flow. Systematic airborne ice radar sounding must first identify potential core sites. Such work must be done with careful long-range planning, because currently only one radar system exists which is capable of penetrating several thousand meters of ice and available flight time is very limited. Surface-based ice radar sounding and atmospheric sampling, snow pits, and shallow cores at those sites must then confirm and add detail to the airborne radar survey data and determine the quality of the paleoenvironmental information that can be expected from each site. Thus several years of site selection research must precede drilling of a deep core.

Shallow and intermediate (10-1000 m; 102 - 104 yr) ice cores should be obtained in polar regions but also at various low latitude/high altitude sites. Drilling of these cores is logistically easier because it can generally be accomplished in one season by a relatively small group. However, site selection for shallow and intermediate cores requires, just like the long cores, several years of field studies preceding the drilling.

Radar surveying is not such a limiting factor here since more than one radar system is available that will penetrate to depths of several hundred to a thousand meters, and in thicker ice the cores end sufficiently far above bedrock that bedrock topography is only a minor factor in site selection. Major difficulties for the low latitude programs are the development of support and collaboration for the research project in the countries where the ice is located, and the search for a suitable ice mass in a climatically and topographically highly variable terrain. Study of the gases trapped in the ice is especially difficult because it requires transport of frozen core samples from a remote site.

As our understanding of the global ocean-atmosphere-cryosphere-biosphere interactions that shape global environmental change increases over the coming years, new questions that may be answered by ice core analysis will arise. To maintain a lively and fruitful interaction between ice core research and other areas of global change research, we must be able to obtain cores suitable to answer specific questions without the long delays for site selection discussed above. Since the characteristics of the core most suited to settle a specific question depend on that question, drill site selection without delay requires that an existing database be available consisting of -systematic airborne radar surveys and surface studies of several areas. The database could be shared with other fields, e.g. the radar bedrock data with geophysics and tectonics, the ice surface data with meteorology and climate modelling.

The Arctic and the Antarctic, research programs are organizationally and logistically independent. Parallel programs for ice core research in these areas can therefore be developed. Simultaneous ice core research in both the Arctic and the Antarctic will allow rapid identification of global environmental changes recorded by core features in both polar regions. Our plan for ice core drilling and research is based on the assumption that research in the Arctic and the Antarctic will proceed in parallel. This will require (internal) management of the analytical capacity of the various research groups involved as well as coordination of the Arctic and Antarctic programs so that major drilling and sampling years in both areas do not coincide. Polar intermediate and shallow cores as well as lower latitude cores can be obtained in a single season and can be fitted into the long-range deep drilling schedule as needed. The intermediate and shallow cores address the spatial variability in the paleoenvironmental record from ice cores and are an integral part of the long-range U.S. ice core research plan.

<- Back | Table of Contents | Next ->