Science, 19 September 2008, Vol. 321, No. 5896, p. 1648; DOI: 10.1126/science.1157525

Ancient Permafrost and a Future, Warmer Arctic

Duane G. Froese,^1* John A. Westgate,² Alberto V. Reyes,¹ Randolph J. Enkin,³ Shari J. Preece²

Climate models predict extensive and severe degradation of permafrost in response to global warming, with a potential for release of large volumes of stored carbon. However, the accuracy of these models is difficult to evaluate because little is known of the history of permafrost and its response to past warm intervals of climate. We report the presence of relict ground ice in subarctic Canada that is greater than 700,000 years old, with the implication that ground ice in this area has survived past interglaciations that were warmer and of longer duration than the present interglaciation.

¹ Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T5M 0M3, Canada.
² Department of Geology, University of Toronto, Toronto, ON M5S 3B1, Canada.
³ Geological Survey of Canada–Pacific, Sidney, BC V8L 4B2, Canada.

^* To whom correspondence should be addressed. E-mail: duane.froese@ualberta.ca