With the completion of the two ice coring programs (GISP2 and GRIP) in Summit Greenland, a new era in paleoenvironmental investigation has been opened. These records are of extreme significance to our understanding of environmental change not only because they provide the highest resolution continuous, multi-parameter view produced thus far but, as importantly, because the two records can be used to validate each other (e.g., dating, presence of events, length of the environmental record, presence or lack of discontinuities), the only such experiment of this magnitude in ice core research.
In addition to providing a remarkable paleoenvironmental record, the GISP2 ice core also provides our first view of the basal conditions (clear ice into silty ice into bedock) beneath the central (spreading) region of a polar ice sheet. The Summit drilling programs, future deep drilling in polar glaciers and our undestanding of dynamical glaciology (e.g., basal ice processes, flow modeling) will benefit greatly from the examination of these basal records.
Now that the longest ice core record from the Northern Hemisphere is a reality, it is time to develop new ice core records for the Southern Hemisphere and fill in regional details throughout the Earth. Future deep drilling in the Antarctic promises new approaches to our understanding of environmental change. For example, the recovery of ice cores from Antarctic sites with accumulation rates similar to those at GISP2 (e.g., interior West Antartica) will provide equivalent (continuous, high resolution and multi-parameter) and comparable records from which bipolar studies of climate change (response and forcing) can be undertaken. In addition, the recovery of ice cores from Antarctic sites with lower accumulation rates and thicker ice than that at GISP2 (e.g., interior East Antarctica) will eventually provide the longest ice core records (spanning several glacial/interglacial cycles) available on Earth. In addition to planning future GISP2/GRIP-scale deep drilling efforts in Antarctica, it is imperative that ice coring activities also continue throughout the Arctic (e.g., north Greenland, the Arctic Islands) and low- to middle-latitude/high-elevation sites (e.g., Asia and South America). These efforts will be essential to our understanding of regional scale climate change events and to the eventual linkage of existing ice core records.
Within the coming months and years, ice core records may provide the perspective needed to dramatically advance our understanding of climate change (response and forcing) and perhaps the perspective needed to understand the consequences of our involvement in this dynamic environment. In addition, they may also provide the framework needed to incorporate and further interpret the wealth of other proxy environmental records that are already available (e.g., tree rings, marine and lake sediments) leading toward more robust global to regional scale paleoenvironmental reconstructions.
Acknowledgments. We would like to thank the Office of Polar Programs, National Science Foundation, for their support and encouragement; the Polar Ice Coring Office of the University of Alaska, Fairbanks, for drilling and logistic support; the 109th Air National Guard (Scotia, New York) for many years of close cooperation, support and enthusiasm; the GISP2 Science Management Office of the University of New Hampshire for their scientific and logistic coordination; and our GRIP colleagues for the seasons we shared as neighbors in central Greenland. The Greenlandic and Danish Governments kindly granted permission for GISP2 to work in Greenland. Finally, we would like to thank all of our GISP2 colleagues (scientists, drillers, support crews) for their unflinching dedication, efforts and comradery over the duration of the GISP2 field reconnaissance (1987-1988) and drilling seasons (1989-1993).