February 23, 2013
Siberia Could Experience Widespread Permafrost Thaw Due To Global Warming
Lee Rannals for redOrbit.com — Your Universe Online
More evidence is pointing to the nightmare scenario that global warming is taking a toll on our planet.Oxford University scientists say that a global temperature rise of 2.7 degrees Fahrenheit could thaw the ground over a large area of Siberia, threatening the release of carbon from soil.
If the thawing of Siberia's permafrost occurs, it could see that over 1,000 gigatons of the greenhouse gases carbon dioxide and methane are dished out into the atmosphere, adding an even larger global warming threat.
The scientists studied stalactites and stalagmites from caves located along the permafrost frontier in Siberia, where the ground stays permanently frozen in a layer of tens to hundreds of feet thick. Because these cave features only grow when liquid rainwater and snow melt drips into the caves, these formations record 500,00 years of changing permafrost conditions.
Records from 400,000 years ago show that a global warming of 2.7 degrees Fahrenheit is enough to cause substantial thawing of permafrost far north from its present-day southern limit.
"The stalactites and stalagmites from these caves are a way of looking back in time to see how warm periods similar to our modern climate affect how far permafrost extends across Siberia," lead author Dr Anton Vaks of Oxford University's Department of Earth Sciences, said in a statement. "As permafrost covers 24 percent of the land surface of the Northern hemisphere significant thawing could affect vast areas and release gigatonnes of carbon."
He said that this research has big implications for ecosystems in the region, and for the aspects of the human environment.
"For instance, natural gas facilities in the region, as well as power lines, roads, railways and buildings are all built on permafrost and are vulnerable to thawing. Such a thaw could damage this infrastructure with obvious economic implications," Vaks said.
During the study, they used radiometric dating techniques to help determine the age of the growth of cave formation. Data taken from the Ledyanaya Lenskaya Cave near the town of Lensk showed that the only period when stalactite growth took place occurred about 400,000 years ago. During this period, the global temperature was 2.7 degrees Fahrenheit higher than today. They believe that this is the tipping point at which the coldest permafrost regions begin to thaw.
"Although it wasn't the main focus of our research our work also suggests that in a world [2.7 Fahrenheit] warmer than today, warm enough to thaw the coldest permafrost, adjoining regions would see significant changes with Mongolia's Gobi Desert becoming much wetter than it is today and, potentially, this extremely arid area coming to resemble the present-day Asian steppes," Vaks added.
Researchers studying Arctic thermokarst failures in Alaska recently reported similar findings in the Proceedings of the National Academy of Sciences (PNAS). They warned that climate-warming carbon dioxide gas may be releasing into the atmosphere at an unprecedented rate.
This area, like Siberia, holds massive stores of organic carbon that have been frozen in the Arctic permafrost for thousands of years. If it thaws and releases CO2, it could double the amount of greenhouse gas in the atmosphere on a timescale similar to that of man's contribution from the burning of fossil fuels.