Summit County Citizens Voice

Cave study offers clues on temperature threshold

Global permafrost is a significant factor in the climate-change equation. Map courtesy United Nations Environmental Program.

By Summit Voice

SUMMIT COUNTY — Climate scientists have long been warning that a meltdown of Arctic permafrost will trigger a spike in greenhouse gas emissions as long-frozen organic soils give up their carbon to the atmosphere. What’s not yet clear is how fast and how much of the permafrost will melt, but a new study helps identify a temperature threshold that could lead to widespread melting.

A team led by Oxford University scientists studied stalactites and stalagmites in caves along Siberia’s permafrost frontier, where the ground begins to be permanently frozen in a layer tens to hundreds of meters thick.

The stalactites and stalagmites only grow when liquid rainwater and snow melt drips into the caves. The formations record 500,000 years of changing permafrost conditions, including warmer climate periods. After studying the paleoclimate clues in the caves, the researchers concluded that another 1.5 degrees of warming would be 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 percent 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,” he said. “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.”

“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,” Vaks said.

A report of the research is published in this week’s Science Express. The team included scientists from Britain, Russia, Mongolia and Switzerland.

Filed under: Arctic, climate and weather, Environment, global warming Tagged: | Arctic, climate change, Environment, global warming, global warming tipping points, Greenhouse gas, Oxford University, permafrost