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The NEEM ice coring project
During 2007-2011, a team of ice core researchers will drill through the ice sheet in North-West Greenland to retrieve ice from the previous interglacial, the Eemian, which ended about 115,000 years ago. Ice core samples from the Eemian will contribute to the understanding of the dynamics of climate under conditions similar to those of a future warming climate.
The need for a new ice core
None of the former deep ice cores from Greenland (Camp Century, DYE-3, GRIP, GRIP2, or NGRIP) contains complete and undisturbed layers from the Eemian, because the layers have either melted or have been disturbed by ice flow close to the bedrock.
Greenland temperatures were about 3-5°C warmer higher than present during the Eemian, making the Eemian a useful analogue to the future climate, which due to global warming is projected to warm by 2-4°C per century. By understanding how the Eemian climate evolved, we can improve our ability to make projections for how our current climate will evolve in the future.
The drill site
The choice of drill site is based on criteria giving the best possible conditions for retrieving the old Eemian ice:
- The ice must be thick, as large ice thickness implies more annual layers.
- The bedrock most be flat, because uneven bedrock causes irregular ice flow that can distrub the ice layering
- The precipitation should be moderately high. Large annual snowfall results in fast ice flow and thereby fast thinning of the lower, older parts. In contrast, low snowfall will mean that the annual layers become harder to detect and analyse.
- The dril site should be on an ice divide. The ice divide is the linie that separates the east-flowing part from the west-flowing part. The oldest ice layers are found near ice divides.
The NEEM drill site has been chosen based on radar profiling of the ice internal layers and the bedrock topography. The measurements show that the ice thickness is close to 2542 m.
Centre for Ice and Climate is coordinating the NEEM project and is managing the logistical efforts needed to meet the logistical challenge of operating on the Greenland ice sheet.
The project started in 2007, when 2 tracked vehicles dragged equipment from the previous drill site, NGRIP, to the NEEM drill site. The camp is being built in 2008, where the drilling will also start. The majority of the ice core drilling will take place during the summers of 2009-2011, during which the camp will accommodate about 30 researchers and technicians for 3-4 months.
Analyzing the ice
Understanding the dynamics of the climate system is the main objective of the extensive analysis program, which involves many different types of measurements:
- the isotope ratios of the ice reveal past temperatures in Greenland and at the source areas that supply the moisture that ends up as precipitation over the ice sheet
- impurities in the ice reflect the impurity load of the atmosphere of the past
- gas bubbles trapped between the snow crystals contain samples of the atmosphere of the past, reflecting the atmospheric composition, e.g. the amount of greenhouse gasses
- the crystal structure of ice, the temperature of the bore hole, and the content of biological material in also provide information about past climatic conditions
The analysis of the more than 2½ km ice core will be performed at the Centre for Ice and Climate and cooperating research groups from 13 nations.
Modelling of the ice flow suggests that the annual layers in the Eemian ice are about 7 mm thick. It will therefore be possible to investigate on an annual basis how the previous interglacial started and ended.
The study of ice cores can thus both improve our understading of the history of our climate and improve our ability to make good projections of future climate.
- about the NEEM project in the project description (PDF file)
- about how ice cores are analysed at the Centre for Ice and Climate
- about the field work in the field diaries
All transport to and from the camp is carried out in ski-equipped Hercules LC-130 airplanes. Watch the plane taxiing and taking off from camp.
(Watch Flash movie below or download MPEG-movie)