Difficult to Melt
But a study led by Duane G. Froese of the University of Alberta concludes permafrost is far more resistant to climate change than previously claimed. The study, “Ancient Permafrost and a Future, Warmer Arctic” (Science, September 19, 2008), examines ancient ice, determined to be 740,000 years old, found in the Yukon. The permafrost has, indeed, remained “permanent” despite having experienced climate change—both warming and cooling—for hundreds of thousands of years.
Ice core samples, for example, show temperatures were repeatedly warmer in the Arctic during the past 740,000 years than they are today.
The Froese study calls into question the accuracy of climate models predicting long-term damage to permafrost from global warming. The study authors put it as follows:
“Climate models predict extensive and severe degradation of permafrost in response to global warming, with a potential of the 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.”