Thawing permafrost in the Artic and sub-Arctic regions will likely produce a gradual and prolonged release of large quantities of greenhouse gases spanning decades as opposed to an abrupt release in a decade or less, says a new study published in the journal Nature.
Permafrost in High Arctic. Image credit: TheBrockenInaGlory / CC BY-SA 3.0
As the Earth’s climate continues to warm, researchers are working to understand how human-driven emissions of carbon dioxide will affect the release of naturally occurring greenhouse gases from arctic permafrost.
As the perennially frozen soil continues to thaw, the increase of greenhouse gas emissions could significantly accelerate warming conditions changes on Earth.
An estimated 1,330 – 1,580 billion tons of organic carbon are stored in permafrost soils of Arctic and subarctic regions with the potential for even higher quantities stored deep in the frozen soil. Thawing and bacterial decomposition cause the release of carbon dioxide and methane greenhouse gases into the atmosphere.
“Our big question is how much, how fast and in what form will this carbon come out,” said Prof Ted Schuur of Northern Arizona University, who is the first author on the Nature paper.
Permafrost has warmed nearly 11 degrees Fahrenheit in the past three decades. In the 1980s, the average temperature of permafrost in Alaska, Russia and other Arctic regions was nearly 18 degrees Fahrenheit. Now the average is just over 28 degrees Fahrenheit.
“Human activities might start something in motion by releasing carbon gases but natural systems, even in remote places like the Arctic, may add to this problem of climate change,” Prof Schuur said.
“The data from our team’s syntheses don’t support the permafrost carbon bomb view,” said study co-author Dr A. David McGuire of the U.S. Geological Survey and the University of Alaska Fairbanks Institute of Arctic Biology.
“What our syntheses do show is that permafrost carbon is likely to be released in a gradual and prolonged manner, and that the rate of release through 2100 is likely to be of the same order as the current rate of tropical deforestation in terms of its effects on the carbon cycle.”
Many climate modelers do not incorporate the effects of carbon and methane release from permafrost thawing into their models.
Prof Schuur and co-authors hope the new findings will help modelers prioritize the inclusion of those effects in climate models.
_____
E. A. G. Schuur et al. 2015. Climate change and the permafrost carbon feedback. Nature 520, 171–179; doi: 10.1038/nature14338
