New, extremely detailed data from investigations of ice cores from Greenland show that the climate shifted very suddenly and changed fundamentally during quite few years when the ice age ended. Together with an international team, researchers from the Niels Bohr Institute of University of Copenhagen have analyzed the ice cores from the NorthGRIP drilling through the Greenland ice cap, and the new results have been published in the journals Science and Science Express.

The ice in Greenland has been formed by snow that stays year after year, and gradually is compressed into a thick ice cap. The annual layers provide information about the climate during the years when the snow was falling so the ice is a record of the climate of the past, and ice core drillings through the 1.86-mile thick ice cap show the climate 125,000 years back in time.

In the Northern Hemisphere, the last glacial ended in strong variations of temperature, which consisted of two warming periods interrupted by a cold period. The first sudden warming happened 14,700 years ago. The temperature in Greenland increased by more than 10 degrees, and in the milder climate, the first people of the Stone Age went towards Northern Europe and Scandinavia. But it did not last long – 12,900 years ago, the ice age struck once more with a new severely cold period, which lasted until 11,700 years ago, at which time the ice age ultimately ended. The ice cores from Greenland, which reflect the climate in the Northern Hemisphere, show that tremendously fast climatic changes were involved.