|Title||Field season 2011. North Greenland Eemian Ice drilling (NEEM) 2007‐2012: NEEM 3rd season of deep ice core drilling and core processing|
|Author(s)||Lars B Larsen , Simon G Sheldon, Jørgen P Steffensen|
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 in1989‐1992 (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.
Deep drilling was done in 2009 and 2010. In 2010 cores with basal material were drilled, and the goal of obtaining a stratigraphic climate profile through the ice was completed. Although ice core drilling is almost complete, there is still ice core material in the science to be analysed. Therefore, the main goal of NEEM in 2011 is to perform experiments with drilling into rock at the base of the deep hole, to perform experiments with replicate coring and to continue
core processing with the most comprehensive and advanced ice core analysis equipment ever brought to the field.
NEEM 2011 camp will also be a platform for some associated projects: PARCA AWS stations, Ice2Sea shallow coring, seismic stations, deep hole logging, water vapour sampling, strain net, radar survey and experiments with unmanned airborne radar.
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.
This report provides the participants with information on the conditions in Kangerlussuaq, Thule AB and the NEEM camp. It includes a summary of all individual travel dates and information on science programs. It also contains information and rules on environmental issues, work safety and disaster preparedness. All participants are assumed to be familiar with the content of this report.
In addition to general information, the report contains reference information of special interest for the Field Operation Managers and Field Leaders.
|Categories||Deep Drilling, Field Logistics/Camps, Ice Core Processing/Storage/Quality|
|Equipment||EPICA/NGRIP Drill, Hans Tausen Drill(s)|
|Citation||Lars B Larsen , Simon G Sheldon, Jørgen P Steffensen ( 2011 ) Field season 2011. North Greenland Eemian Ice drilling (NEEM) 2007‐2012: NEEM 3rd season of deep ice core drilling and core processing. 1-107 .|