Ice Cores: NEEM

SIL Measurements

Why Study?

In the last 45 years deep ice coring projects have been recurring roughly every ten years. The drilling at Camp Century (1963-1966) was conducted as part of a U.S. Army engineering experiment during the Cold War. When the 1370 m long Camp Century ice core was analysed for stable isotope composition the first ice core based climate record into the last glacial period was revealed in 1969-1972. In the seventies the science community saw much controversy about in particular the very fast jumps in the isotope record from the last glacial period.

GISP (Greenland Ice Sheet Program), a collaboration of scientists from the U.S., Switzerland and Denmark, resulted in a 2037 m long deep ice core drilled at Dye"3 in South Greenland (1979-1981). The Dye"3 record confirmed the fast jumps from Camp Century as being a result of fast climatic oscillations during the last glacial period. The climate oscillations have later been called 'Dansgaard-Oeschger cycles' or 'Interstadials'.

To obtain the longest climatic record a deep ice coring was planned at the summit of the Greenland Ice Sheet. Due to political difficulties, the planned drilling was conducted by a European team at the very summit of the ice sheet in 1989-1992 (GRIP, GReenland Ice core Project) and a US team some 30 km West of the summit in 1989-1993 (GISP2) in two parallel drillings. As a result, scientists got two ice core records, GRIP was 3027 m long and GISP2 3065 m long, which could be compared in great detail. Much to the dismay of both ice coring teams, it turned out that although both the GRIP and the GISP2 record contained ice from the previous interglacial, the Eemian, they also had disturbed layer structures in ice older than 80,000 years, well before the Eemian was reached. The old GISP2 site is today the permanent US Summit station.

To obtain an undisturbed record of the early glacial, the Eemian and beyond, NGRIP (North GReenland Ice core Project) was formed as a Danish led international ice drilling project on the ice crest some 300 km NNW of summit. The project started in 1996 and ran in parallel with the two European ice core drillings in Antarctica, the EPICA project. Due to set-backs caused by a lost drill and warm ice at the base, NGRIP did not reach bedrock at 3090 m before 2004. The NGRIP ice core turned out to contain both a curse and a blessing. Due to basal melting caused by geothermal heat, the oldest ice, including the first half of the Eemian. Thus the climate record could only be extended to 125,000 years back in time. On the other hand however, basal melting insured undisturbed stratigraphy along the whole ice core length and insured an unparalleled temporal resolution which has allowed for an annually counted ice core time scale 60,000 years back in time.

With the present discussion about global warming the Eemian period has attracted a lot of attention. In Europe the Eemian was about 5 degrees C warmer than today and sea levels were some 5 m higher. The Eemian serves as a Nature's parallel to a future with global warming. Therefore NEEM (North Greenland Eemian ice drilling) has as a goal to obtain a complete ice core record from the Eemian for a thorough comparison with our present climate in the Holocene. NEEM is the sixth deep ice coring in Greenland.

The main goal of NEEM in 2009 is to perform deep ice core drilling and core processing with the most comprehensive and advanced ice core analysis equipment ever brought to the field. NEEM 2009 camp will also be a platform for some associated projects: British Antarctic Survey radar tests, a seismic station, firn gas pumping, trace gas analysis and some biological tests.

The main transport between NEEM camp and Kangerlussuaq will be by ski equipped LC"130 aeroplanes from the U.S. Air Force, 109th Tactical Air Group, Scotia, N.Y. The planes are provided as part of the logistical contribution to NEEM from the U.S. National Science Foundation.

Copenhagen, March 15th, 2009

Lars Berg Larsen, Simon Sheldon, J.P.Steffensen

Participants

NEEM ice core drilling project, www.neem.ku.dk.

Alfred-Wegener-Institute, British Antarctic Survey, Centre for Ice and Climate - Niels Bohr Institute, Climate and Environmental Physics - University Bern, Cold & Arid Regions Res. Inst - Chinese Academy of Sciences, Department of Physical Geography and Quaternary Geology - Stockholm University, Geological Survey of Canada, IMAU, INSTAAR - University of Colorado, Institute of Earth Sciences - University of Iceland, Korea Polar Research Institute, LSCE, National Institute of Polar Research, University Libre de Bruxelles,

SIL Role

The INSTAAR Stable Isotope Lab has been involved with the NEEM project from its conception, in both logistical planning and science. All air logistical support for NEEM is provided through an NSF funded INSTAAR proposal that facilitates the 109th Air National Guard to provide ski equipped LC-130's to Greenland for the enormous job of transport of all people and cargo to the NEEM site. The INSTAAR SIL will be analyzing NEEM sub samples for deuterium isotopes and helping with the interpretation of the paleoclimate implications from the isotope records by way of an additional NSF supported grant (J. W.C. White). This project is in collaboration with science groups from over 14 other nations.

Location

Funding

• US National Science Foundation

Other

• NEEM main website

Research: