A team of scientists from Britain, Russia, Mongolia, and Switzerland have released a report which finds that evidence obtained from Siberian caves suggest that a global temperature rise of 1.5 degrees Celsius could result in permanently frozen ground end up thawing across a massive swathe of Siberia, threatening a release of carbon dioxide.
Such a thaw in Siberia’s permafrost could release 1,000 giga-tonnes of carbon dioxide and methane into the atmosphere.
Such a release of greenhouse gas emissions is part of what many refer to as a feedback loop; wherein increased levels of carbon dioxide cause global warming which causes the thaw of permafrost which releases carbon dioxide which takes us back to the beginning and enhances the global warming.
The data for the scientists’ report comes from a study led by Oxford University scientists of stalactites and stalagmites from caves located along the ‘permafrost frontier’. Such a ‘permafrost frontier’ is simply the place where ground beings to be permanently frozen in a layer tens to hundreds of metres thick.
Stalactites and stalagmites only form when liquid rainwater and snow melt drips into caves, subsequently creating formations that record 500,000 years of changing permafrost conditions, including warmer periods similar to the rising temperatures of today’s climate.
The scientists found in the stalactites and stalagmites of the Ledyanaya Lenskaya Cave — near the town of Lensk, at a latitude of 60 degrees North — evidence of a particular warm period labelled the Marine Isotopic Stage 11 that took place approximately 400,000 years ago and that had temperatures 1.5 degrees Celsius above today’s current average.
There was no growth in the stalactites and stalagmites when the world was 0.5-1 degrees Celsius warmer than it is today, suggesting that 1.5 degrees Celsius is the ‘tipping point’ at which the coldest permafrost regions begin to thaw.
The evidence subsequently suggests that a global warming of 1.5 degrees Celsius compared to the present 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,” said Dr Anton Vaks of Oxford University’s Department of Earth Sciences, who led the work. “As permafrost covers 24% of the land surface of the Northern hemisphere significant thawing could affect vast areas and release giga-tonnes of carbon.”
“This has huge implications for ecosystems in the region, and for 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.”
Dr Vaks said: ‘Although it wasn’t the main focus of our research our work also suggests that in a world 1.5 degrees Celsius warmer than today, warm enough to melt 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.’
Source: Oxford University