COMPILED REPORTS OF THE
U.S. ICE CORE RESEARCH WORKSHOP

U.S. ICE CORE RESEARCH AND GLOBAL CHANGE

(Moderator- P. A. Mayewski)

For scientists interested in global change problems, ice core records provide a unique and invaluable medium for studying the past. These records yield both direct and proxy links to the paleoenvironment over periods potentially as long as hundreds of thousands of years with resolution down to seasonal scale for time-series on the order of hundreds to thousands of years. In addition, the fact that most ice core records are retrieved from locations rarely, if every, occupied by observers adds to the value of these data sets.

In response to the growing importance of such records, the NSF's Division of Polar Programs recently sponsored the U.S. Ice Core Research Workshop in Durham, New Hampshire. At the workshop, 45 U.S. scientists actively involved in ice core research together formulated a globally-based strategy planned through the 1990s, that would result in -the development of an ice core program integrally tied to global change issues. Representatives from the European ice core research community also attended, to aid in discussions of anticipated joint international efforts.

A prime stimulus for the workshop was the newest planned major U.S. ice core effort, GISP II (Greenland Ice Sheet Project II). A proposal solicitation for this project appeared in EOS (24 May 1988).

GISP II and a corresponding European effort GRIP (Greenland Icecore Program), plan to retrieve a ~3200 meter deep core which would extend to the base of the central Greenland ice sheet. Both programs are expected to run from 1989-1994. Conditions at the proposed drill site are such that seasonal resolution will be possible back to ~ 10,000 years and the total record could include the last ~ 200,000 years. A section of the workshop dealt with detailed discussions of the properties to be measured on the core, drill technology, core processing and data management.

At the workshop plans were also drafted for drilling efforts in both West and East Antarctica. Emphasis was given to sites in West Antarctica in light of the extensive programs already undertaken by U.S. glaciologists interested in the dynamics and potential stability of this ice mass. Participants proposed a 1991 start for drilling to the base of the Antarctic ice sheet.

Data comparisons between GISP II and Antarctic deep drilling programs as well as deep sea sediment, lake sediment and glacial geologic records will be necessary to answer questions dealing with the hemisphere to hemisphere synchroneity of global change events.

Considerable enthusiasm was also expressed for immediately expanding the current array of low- to middle-latitude, high elevation coring sites. The suitability of sites in Asia, South America, Europe, and North America for the recovery of ice core records has been well documented, but they remain a virtually untapped paleoenvironmental. resource. These sites can provide documentation of the remote atmosphere and of major atmospheric circulation phenomena, such as ENSO events, while also completing the global linkage between Antarctic and Arctic ice core records.

Workshop participants detailed the analyses (Table 1) that can be conducted on ice cores, noting the considerable potential for new types of measurements and additional new technologies. The repertoire of measurements has been expanded in the last few years as more geochemists, atmospheric chemists, geophysicists, climatologists, and modelers have become involved in the analysis and interpretation of ice cores. As a result of these new interactions, ice core programs now integrally relate a range of measurements on not only ice cores, but also on the atmosphere, surface snow and snowpit samples. 

The documentation of global change is a major key to understanding the history of and the current changes in the global system. As ice core programs such as GISP II come on-line, they will provide an exciting new look at the past; the global array of ice core retrieval sites proposed at the workshop has the potential to add important details (Table 2) concerning the changes in and characterization of major components in the global system.

Table 1
Ice Core Measurements

Table 2
Global Change Components That Can be 
Documented Using Ice Core Records

- Global Climate
     e.g., greenhouse gases 
          aerosols
          atmospheric temperature 
          stratosphere/troposphere exchange 
          air mass sources 
          precipitation patterns

- Global Ice
     e.g., distribution of glaciers, snow, and sea ice 
          ice volume and sea level 
          glacier dynamics and ice properties 

- Biogeochemical Cycles (C, N, S, etc.)
     e.g., biogenic gases 
          marine aerosols 
          continental aerosols 
          atmospheric interconversions

- Anthropogenically Derived Material
     e.g., radiatively active gases and aerosols 
          inorganic and organic pollutants 

- Geologic and Extraterrestrial Activity
     e.g., volcanic activity 
          geomagnetic field 
          solar activity 
          extraterrestrial fluxes

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