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Drastic climate change near end of last Ice Age

Date: 24-Jun-08
Author: University of Colorado at Boulder

Information gleaned from a Greenland ice core by an international science team shows that two huge Northern Hemisphere temperature spikes prior to the close of the last ice age some 11,500 years ago were tied to fundamental shifts in atmospheric circulation.

The ice core showed the Northern Hemisphere briefly emerged from the last ice age some 14,700 years ago with a 22-degree-Fahrenheit [12.2-degree-Celsius] spike in just 50 years, then plunged back into icy conditions before abruptly warming again about 11,700 years ago.

Startlingly, the Greenland ice core evidence showed that a massive "reorganization" of atmospheric circulation in the Northern Hemisphere coincided with each temperature spurt, with each reorganization taking just one or two years.

The team used changes in dust levels and stable water isotopes in the annual ice layers of the two-mile-long [3.2-km] Greenland ice core, which was hauled from the massive ice sheet between 1998 to 2004, to chart past temperature and precipitation swings. Their paper was published in the June 19 issue of Science Express, the online version of Science.

Extruding an ice core: Scientists extrude the core from its barrel with the utmost care. Any butyl acetate on the core surface is carefully cleaned off before sawing the ice into 2-meter [7-ft.] sections. The cloudy layers clearly visible in this 6-m [20-ft.] core section were formed when dust fell onto the ice sheet and was entrained in the ice. Courtesy: Mark Twickler, University of New Hampshire / NOAA Paleoclimatology Program / U.S. Department of Commerce

Full story: Greenland Ice Core Analysis Shows Drastic Climate Change Near End Of Last Ice Age