Recommendations for a U.S. Ice Coring Program

Ice and climate are inextricable 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 climate, either purposeful or inadvertent, 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 climate 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 that affects 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.

Recommendations for a U.S. Ice Coring Program 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.

This 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.