a_north_greenland_ice_core_reveals_climate_swings | CU-Boulder Environmental Studies Program

News Aug 07, 2004

A North Greenland ice core reveals climate swings

Boulder Flatirons from the south

James White (GEOL, ENVS, and INSTAAR), Trevor Popp, and Annalisa Schilla are part of a team of international researchers working on the North Greenland Ice Core Project (NGRIP), which recently published an overview of the 123,000 year old, undisturbed deep-core record. The older part of the record shows that the Eemian period prior to the last glacial period was slightly warmer than the present day before it gradually cooled and sent Earth into an extended deep freeze. The highly detailed record of this transition is a new discovery. Although two other deep-ice cores were retrieved from Greenland in the 1990s, those cores could not provide reliable climate records of this transition because of ice layer "folding" near bedrock. The new NGRIP ice core record indicates Eemian-period temperatures, over the polar regions at least, were stable and roughly 9 degrees Fahrenheit warmer than temperatures in the present interglacial. The transition from the Eemian into the most recent glacial period was slow and gradual, marked by general cooling and deterioration of the climate over several thousand years. The isotopes in the NGRIP ice and four Greenland ice cores drilled in recent years also indicate that while the northern part of the Greenland ice sheet was fairly stable during the Eemian, the ice sheet in southern Greenland may have been dramatically thinner or even nonexistent. The NGRIP ice core also provides evidence of air temperatures jumping 9 degrees Fahrenheit in just five decades roughly 115,000 years ago, just prior to the slide from the Eemian into the glacial period.

Published in Nature, 9 Sept 2004

News Source: CU-Boulder News Center

Websites: North Greenland Ice core Project - NGRIP

ENVS Faculty: James White

ENVS News Category: Publication

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