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Thawing Permafrost Throws Off Global Warming Forecasts

Estimates skewed because of exclusion of greenhouse gas emissions from now-frozen soil, report says

by Cheryl Hogue
November 29, 2012 | A version of this story appeared in Volume 90, Issue 49

Predictions of climate change—key to many policy-making efforts on global warming—likely lowball anticipated warming because they fail to account for emissions from thawing permafrost, says a new report. For instance, scientific assessments by the Intergovernmental Panel on Climate Change (IPCC) don’t factor in permafrost emissions.

The report, released last week by the United Nations Environment Programme (UNEP), points out that human-caused climate change is expected to cause significant amounts of permafrost to thaw. If that happens, organic material in this soil, frozen for millennia, will rot and release carbon dioxide and methane.

Those greenhouse gas emissions from permafrost will add to global warming, the report says. This, in turn, will further accelerate thawing of the material, which is found beneath 24% of exposed land in the Northern Hemisphere. It lies under tundra, boreal forests, and alpine regions.

International negotiators hammering out a treaty to limit climate change to 2 °C over preindustrial levels by 2100 need to take into account how emissions from permafrost will amplify global warming, says the report’s lead author, Kevin Schaefer, a researcher at the University of Colorado’s National Snow & Ice Data Center. He adds, “The release of CO2 and methane from warming permafrost is irreversible.”

The UNEP report recommends that IPCC conduct a special assessment of how emissions from warming permafrost would influence Earth’s climate.


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