A new study details changes in Earth's climate from more than 100,000 years ago and indicates that the last interglacial, the term for the periods between "ice ages", was warmer than previously thought. 


The new results from the North Greenland Eemian Ice Drilling (NEEM) project, managed by Denmark's Centre for Ice and Climate, show that during the Eemian interglacial, the climate in North Greenland was about 8 degrees Celsius warmer than at present. The Eemian interglacial period began about 130,000 years ago and ended about 115,000 years ago. 

 The Greenland ice core layers, formed over millennia by compressed snow, are being studied in detail using a suite of measurements, including stable water isotope analysis that reveals information about temperature and moisture changes back in time. Lasers are used to measure the water stable isotopes and atmospheric gas bubbles trapped in the ice cores to better understand past variations in climate on a year-by-year basis, similar in some ways to a tree-ring record. 

Despite this strong warming signal during the Eemian, a period when the seas were roughly four to eight meters higher than they are today, the surface in the vicinity of NEEM was only a few hundred meters lower than its present level, which indicates that the Greenland ice sheet may have contributed less than half of the total sea rise at the time. 




"The new findings reveal higher temperatures in Northern Greenland during the Eemian than paleo-climate models have estimated," said Dorthe Dahl-Jensen of the University of Copenhagen, the NEEM project leader. "The good news from this study is that Greenland is not as sensitive as we thought to temperature increases in terms of disgorging ice into the ocean during interglacial periods. The bad news is that if Greenland did not disappear during the Eemian, Antarctica, including the more dynamically unstable West Antarctica, must be responsible for a significant part of the 4-8 meters of sea-level rise."






 Published in Nature