NEEM Reaches Bedrock

News

By Nick Mott
Fall 2010

Dorthe Dahl-Jensen

Photo 1: NEEM researchers celebrate reaching bedrock.

For polar scientists in Greenland, Tuesday July 27, 2010 was a day of celebration.

After years of Arctic work, researchers at NEEM, an ice core drilling site in Northern Central Greenland, reached bedrock at a depth of 2537.36 m. Professor Dorthe Dahl-Jensen held the final chunk of the core, a symbol of five years’ perseverance, over her head in triumph as photographers snapped pictures.

The site was selected to obtain Eemian ice, or ice from the last interglacial period. In this period, the climate was remarkably similar to the climate of today. NEEM researchers hoped to find a drilling site with clean, intact layers of Eemian ice. In order to discern the condition of the layers, CReSIS researchers conducted a radar survey of the site during the first year of drilling. “We had a radar depth sounder that we pulled behind a tracked vehicle and did a grid right around the site to map the bedrock and also to try to map some of the deeper internal layers,” said CReSIS faculty member Carl Leuschen.

CReSIS researchers were part of more than 300 scientists from 14 nations working on the project. Leuschen explained the significance of the core.

“As the snow falls, these gases get trapped in the snow. They essentially are trapped there, and so as more and more snow falls, they compress into ice. What we have in the ice is essentially samples of past atmospheres. By drilling these ice cores, they can get the gases out of the ice sheets at different depths and look at climate history.”

Eemian ice dates from about 115,000 to 130,000 years ago. Ice from this period is particularly useful because of its similarities to the current climate. It may therefore help to predict future changes in climate, Leuschen said. NEEM researchers hope that their findings will help determine the extent to which the melting Greenland Ice Sheet will influence sea level rise, and they expect to find a plethora of data about the Eemian period, at which time the temperature was about 2-3 degrees Celsius warmer than it is today. They obtained even older ice near bedrock, ice that should house DNA and pollen that scientists can use to determine the sort of plant life that existed on the site before it was iced over millions of years ago.

The NEEM project is headed by the Centre for Ice and Climate at the University of Copenhagen. Leuschen hopes that the success in Greenland means continuing CReSIS’ long history of collaboration with both the University of Copenhagen and the larger, international polar science community.