NEEM ice core drilling project på nordvästra Grönland.
NEEM ice core drilling project in North-West Greenland. Photo: Sune Olander Rasmussen, NEEM ice core drilling project.
 

The new findings were published in the scientific journal Nature on 24 January and come from the international deep ice core drilling project NEEM (North Greenland Eemian Ice Drilling) in northern Greenland, which ended last summer after the team had drilled 2.5 kilometers down to the bedrock.

“Analyses of the ice core reveal higher temperatures in North Greenland during the Eemian than climate models have estimated,” says Margareta Hansson, Professor of Environmental Science at the Department of Physical Geography and Quaternary Geology, Stockholm University, and manager for the Swedish participation in the project. Researchers from Stockholm University, Uppsala University and Lund University have participated in the drilling together with partners from 14 different nations.

Despite the strong warming signal during the Eemian – a period when the sea level was about four to eight meters higher than today – the surface of the ice sheet was just a few hundred meters lower than its present level. This indicates that the Greenland ice sheet may have contributed to less than half of the total sea-level rise.

“The good news from this study is that the Greenland ice sheet is not as sensitive to temperature increases during interglacial periods, as we previously thought,” says Margareta Hansson. “The bad news is that if the Greenland ice sheet did not disappear during the Eemian, the Antarctic ice sheet must have been responsible for a significant part of the rise in sea level and thus be more sensitive than we had anticipated.”

The ice from the Eemian period shows clear signs of melting at the surface of the ice sheet. Melt water penetrated the underlying snow, where it re-froze in layers. Such meltlayers are rare in the ice from the last 5000 years, which gives further evidence that the Eemian period was significantly warmer than today. In July 2012, the researchers at the drilling site experienced a few days with extremely high temperatures. It rained, and, just like during the Eemian period, meltlayers were formed in the snow.

While this was an extreme event, the present warming over Greenland makes surface melt more likely, and the predicted warming over Greenland the next 50-100 years will potentially have Eemian-like climate conditions.

“It’s a great achievement for science to gather and combine so many measured ice core records to reconstruct the climate history of the past Eemian,” says Dorthe Dahl-Jensen, University of Copenhagen, the NEEM project leader.

For further information
Margareta Hansson, Professor of Environmental Science at the Department of Physical Geography and Quaternary Geology, Stockholm University, tel +46 (0)8 674 78 65, mobile +46 (0)703 17 24 13, email margareta.hansson@natgeo.su.se

For pictures see www.neem.dk/gallery/