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1. Executive Summary SCIENTIFIC PROGRAM AND GOALS Ice and climate are inextricably linked. The major climate variations of the past "ice ages" are characterized by vast advances of ice over the land and sea. Glaciers and ice sheets affect our current climate. In the future, human modification of climate, either purposeful or inadvertent (for example, by CO2"induced warming) may cause major changes in the global ice volume and sea level. In addition to its active role in the climate system, ice also contains unique information about past climates. A clear reconstruction of climate history is an essential step toward understanding climate processes and testing theories that can predict future climatic changes. Polar ice sheets and some ice caps contain ice layered in an undisturbed, year-by-year sequence. The isotopic composition of the ice, the enclosed air, and trace constituents including particles and dissolved impurities provide information about the composition, temperature, and circulation of the atmosphere. In turn these may provide information about other conditions (for example, biological and solar activity) that affect the atmosphere. The recent ice layers contain a record of anthropogenic pollutants such as carbon dioxide, other greenhouse gases, and heavy metals. Ice cores retrieved from depths down to 2000 m in the Greenland and Antarctic ice sheets have revealed variations in these climatic indicators over the last 150,000 years. Results from ice core analyses have recently revolutionized our thinking about the mechanisms of climatic change. For example, they have revealed that major changes in climate may have occurred very

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abruptly, perhaps in time scales of only a few decades. This remarkable new information was, and is, obtainable only from ice cores because they can provide high time resolution together with the unique possibility of directly sampling prehistoric atmospheres. These newly discovered rapid oscillations in climate have important relevance to the prediction of our future environment. The relative timing and amplitude of changes in temperature (indicated by oxygen isotopes), atmospheric aerosols (from particulates and and soluble impurities), and greenhouse gases (from trapped air) may hold the key to establishing cause and effect in climatic changes. Climatic changes involve feedbacks between various regions of the globe. Sampling the unique climatic indicators found in ice outside the polar regions in high-altitude ice caps can add to an understanding of the globally coupled climate system. For example, analyses of ice cores from Peru show that El Nirfo-Southern Oscillation events are recorded in the ice, thereby enabling the reconstruction of El Nifio history. The time interval that can be sampled at such locations is limited to the last several thousand years, but extremely high time resolution allows the seasonal cycles to be determined. Sampling to these ages requires coring down to shallow or intermediate depths of several hundred meters or less. The ice cores and access to ice sheet interiors provided by drill holes, have also yielded information about the physical properties of the ice. Such knowledge is essential for predicting the future response of the ice sheet to changing climate. The cores taken to date have barely tapped the potential information that is available. Ice much older than 150,000 years, perhaps approaching one-million years, can be found in Greenland and Antarctica. This very old ice can extend ice paleoclimatic data over several ice age glaciation cycles. Ice cores from additional high-altitude, low-latitude locations can provide an expanded geographical coverage back to one to two thousand years before the present. Improved geochemical measurement techniques, such as dry gas extraction and accelerator mass spectrometry, are expanding the range of measurements that is possible. We can be sure that future developments in laboratory techniques will open new horizons. Ice coring in both polar regions and available low-latitude sites has been identified as a major

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scientific priority in previous recommendations from the Polar Research Board, primarily because of the major scientific results obtained from ice coring and because of the potential for dramatically advancing them (National Research Council, 1983a, 1983b, 1985a, 1986a). This report endorses these scientific priorities and strongly recommends that the United States • initiate a program of ice coring and analysis over a period of at least 10 years: • obtain high resolution climatic time series, with wide geographical coverage over the last several thousand years by analyses of cores from various depths at many locations in both polar regions and nonpolar regions: and • obtain long-period climatic time series of several hundred thousand years from both polar regions. The report examines the current status of ice core research in the United States and recommends specific steps to implement an ice coring and analysis program. Successful execution of such a program requires a number of elements, which must be individually successful and interact with one another with positive feedback loops. The elements may be divided into two groups. The first concerns management to mobilize a talented personnel base and to create a mode of operation that allows personnel to focus their energies productively. The second concerns scientific and technical requirements. The report addresses both of these groups, but gives special attention to the first. MANAGEMENT ELEMENTS Scientific and Technical Personnel Requirements: The most essential requirement for a successful ice coring program is talented and capable personnel. Their tasks include arduous field work, complex equipment design, scientific planning, recognition of new scientific problems and their creative solutions, as well as synthesis of the results. Long-term stability of research support is needed in order that personnel can fully commit themselves and focus on the program objectives.

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Current Status: More than 20 U.S. laboratories have an interest in ice core analysis. They provide a personnel base with substantial technical and scientific strength. In contrast, there are only a few experienced scientists committed to participation in field work to ensure the successful execution of this central step of a coring program. Lack of funding continuity militates against the mobilization of an experienced personnel resource focused primarily on ice core research. Recommended Steps: • Ensure reasonable long-term support for the key scientific and technical elements of ice core research. • Ensure retention of the most capable personnel active in ice core research and promote entrance of new talent. • Promote active participation of senior scientific personnel in the field work when critical ice cores are obtained. Management and Organization Requirements: A successful ice coring and analysis program requires positive coupling between scientists, engineers, and field personnel to promote development of optional scientific strategies, advanced interpretation techniques, balance between scientific requirements and technical limitations, and wide utilization of ice core data by the scientific community. Current Status: Funding, operations, and scientific coordination of U.S. ice core research are concentrated in the Division of Polar Programs (DPP) of the National Science Foundation (NSF). Although there is usually coordination through a science plan, research is initiated by proposals from individual institutions operating more or less independently at widely separated geographical locations. In comparison, the strengths of the principal European laboratories arise partly because each has been able to concentrate diverse aspects of ice core research in one unit with strong scientific leadership and positive feedback between capable and committed personnel. There is no standing scientific body responsible for setting directions on ice coring research at either the national or international level in the United States.

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Recommended Steps: • Establish formal organizational connections between key institutions by encouraging multi-institutional proposals. • Support lead institutions willing to commit themselves to excellence in ice core research and to lead in initiation of multi-institutional efforts. • Locate ice core drill inventory, develop new drills, and store ice core at laboratories with strong scientific programs. • Establish a formal structure such that scientific direction within the United States and negotiation of international programs are determined by a representative segment of the U.S. scientific community. • Promote rapid interactive communication and data transfer between researchers through modern computer-based communication systems and a data management program. SCIENTIFIC PLANNING AND TECHNICAL ELEMENTS Requirements: Ice coring should proceed in the context of a global scientific strategy that encompasses both polar regions and lower latitudes. This is needed so that each coring operation adds to the goals of broad geographical coverage and refined or extended time history in an optimum way consistent with available resources. Current Status: There is an excellent scientific plan for a deep coring program in central Greenland. As yet there are no accepted global or regional strategies, and there is no mechanism to create them with input from a representative segment of the scientific community. Recommended Steps: • Establish responsibility for preparation of global and regional coring strategies, with input from the scientific community. Ice Coring Techniques Requirements: A dependable and efficient technological base for obtaining ice cores is essential to ice core research. Three classes of ice cores are needed in order

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to achieve the geographical coverage and time scales required for the scientific programs. These classes are shallow (to about 50 m depth), intermediate (to about 500 m depth), and deep (to 3000 m or greater depth). Current Status: The United States has good coring capability to about 300 m depth, but acceptable quality cores cannot be obtained from depths corresponding to pre-Holocene ice, which lies at more than 1000 m in the major ice sheets. Recommended Steps: • Maintain and update the current shallow and intermediate depth core drill inventory. • Modify an existing or build a new intermediate core drill that can operate in a fluid filled hole to improve core quality and extend the accessible depth coverage. • Build a deep drill based on the most current technology. Ice Analysis Techniques Requirements: Essential laboratory measurements on ice cores include isotope ratios, ionic impurities, microparticles. trace greenhouse eases, and trace elements, as well as various physical properties of the ice. New technologies and new environmental studies undoubtedly will lead to new kinds of measurements. Capacity for large numbers of samples is required to exploit the high time resolution available from ice cores. Onsite processing and analysis of cores are essential first steps before cores are transported to laboratories and repositories. Current Status: Most of the important ice analysis techniques can be carried out in the United States. However, available capacity is limited and could be easily saturated by successful ice coring. The techniques of dry gas extraction so important for sampling the prehistoric atmosphere are missing in the United States. Onsite core handling and analysis techniques are weakly developed.

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Recommended Steps: • Maintain current breadth in laboratory capability. • Increase efficiency and through-put rate especially for accelerator mass spectrometry. • Develop dry gas extraction techniques to advance measurement of climatically active gases including carbon dioxide. Related Needs Requirements: Ice core procurement and interpretation must be supported bv thorough ice dynamic and geophysical measurement and analysis for site selection and assessment of ice flow effects on stratigraphy, bv a strong logistical base for transport to and from remote locations, and bv procedures for storage and distribution of ice cores. Current Status: The United States has adequate capabilities in these areas. Recommendations: • Update geophysical and ice dynamic measurement methods as new technologies become available. • Promote ice dynamic analysis directed specifically to ice core research. • Optimize field operations to minimize transport weight and field time to hold logistical requirements as low as possible. • Adhere to explicit procedures for ice core distribution. RECOMMENDATIONS FOR IMPLEMENTATION • The National Science Foundation (NSF), through its Division of Polar Programs (DPP), should be the lead agency in funding a new Ice Coring and Analysis Program (ICAP), and should manage the program on behalf of the scientific community. • The responsibility for providing NSF with scientific and technical planning and advice in its role as manager of ICAP should be vested in a new U.S. national body, the Ice Core Working Group (ICWG),

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8 composed of active and committed U.S. investigators with multi-institutional representation. The activities of ICWG must provide the scientific direction and the driving force to execute ICAP and include the following specific tasks: Develop a global strategy and coring plans for the Arctic, Antarctic, and low-latitude geographical regions. Plan for drill development. Recommend an appropriate balance between capabilities in shallow, intermediate and deep drilling. Plan for development of advanced geochemical techniques. Represent U.S. scientific interests in international planning. Interface with other disciplines. • The NSF should sequester funds for the support of U.S. ice coring, and seek funds from other agencies concerned with impacts from climatic change. • The United States should coordinate its own efforts with those of other nations through a formally constituted international advisory body. ACTION PLAN Within the first year, the Ice Core Working Group (ICWG) should be established and funding identified within NSF/DPP for a new program of ice core drilling and analysis (ICAP). The ICWG should develop the plans identified in its tasks. A call from the NSF for proposals should go out. During the second year, scientific programs should be started with existing drill technology. Drill development for future scientific programs should also begin. Beginning in the third year and continuing on a yearly basis, ongoing scientific research and drill technology development should be reviewed by ICWG, with the goal of updating the science and engineering plans.