By Barry BrownÂ
Canadian researchers studying the ArcticÂ´s ancient permafrost have discovered 700,000-year-old ice wedges buried in the soil that have survived earlier periods of global warming, adding complexity to predictions about the impact of contemporary climate change. Duane Froese, an assistant professor in the Department of Earth and Atmospheric Science at the University of Alberta, found what he describes as “the oldest ice in North America” in the Klondike region of Canada’s Yukon Territory about 10 feet below the surface.
Because these ice wedges were found under a layer of volcanic ash, researchers from the University of Toronto and the Geological Survey of Canada were able to use a technique known as “fission track dating” of the ash to date it at roughly 700,000 years old.
This means the ice was older than the ash and older than the previous record holder – 120,000-year-old ice wedges found in Alaska.
“The fact that this ice survived the interglacials about 120,000 and 400,000 years ago, which we think were warmer than present, really illustrates how stubborn permafrost can be in the face of climate warming,” Mr. Froese said.
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