29 July 2010
Bedrock of Greenland Ice Sheet reached
Bedrock has been reached Tuesday July 27 2010 at the deep ice core drilling site NEEM on the Greenland Ice Sheet at the depth 2537.36 m.
The Eemian is the last interglacial period, when climate was warmer than today, and sea level 5 meters higher, and is our best analogue for future climate. Scientists from 14 nations participated in NEEM, the most international ice core effort to date. After five years of work, ice from the warm interglacial Eemian period, 130.000 to 115.000 years before present and even older ice has been recovered. The last 2 m of ice above the bedrock contains rocks and other material that has not seen sunlight for hundreds of thousands of years.
"We expect the ice to be rich in DNA and pollen that can tell us about the plants that existed in Greenland before the site became covered with ice, perhaps as long as 3 million years ago", says Professor Dorthe Dahl-Jensen from Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen who leads the extensive research project.
Climate changes mapped out
More than 300 ice core researchers including many young scientists have been in the NEEM camp during the last years. The abrupt climate changes are studied in detail by a suite of different measurements, including the stable water isotopes telling about temperature changes and moisture sources back in time, greenhouse gasses trapped in the ice and biological content that improves our understanding of the natural variability, feedbacks of the carbon and the biogenic cycle and very detailed chemical measurements resolving the annual variations of the climate.
Measurements made on site, meters below the snow surface in the science trench, go beyond what has ever been done at deep ice core camps before. State-of-the-art laser instruments for water isotopes and greenhouse gasses, online impurity measurements and advanced studies of ice crystals are among the impressive instruments at NEEM, one of the most inaccessible parts of the Greenland ice sheet.
Nature's own example
The main goal of the NEEM project is to learn more about the warm Eemian climate period because it in many aspects can be seen as an analogue to the warming we will experience in the future. How reduced was the Greenland ice sheet 120.000 years ago when the global temperature was 2-3 deg C warmer than the present? And how much and how fast did the Greenland Ice Sheet contribute to sea level at that time?
"We expect that our findings will increase our knowledge on the future climate system and increase our ability to predict the speed and final height of sea level rise", says Dorthe Dahl-Jensen.
The progress in the drilling at NEEM can be followed in the online diary on www.neem.ku.dk where pictures from the camp also can be found.
Field Operation Manager
Professor Dorthe Dahl-Jensen, Niels Bohr Institute, University of Copenhagen.