A “sleeping giant” hidden in permafrost soils in northern regions worldwide is waking up and will have important consequences for global warming, says a new report led by Associate Professor Merritt Turetsky, University of Guelph, Canada.

Scientists have long studied how gradual permafrost thaw affecting centimetres of surface soils over decades will influence carbon release to the atmosphere. But Turetsky and an international team of researchers, including Gustaf HugeliusPeter Kuhryand Britta Sannelfrom Stockholm University, are looking at something very different: the abrupt thaw of permafrost that can rapidly transform landscapes through subsidence, inundation and landslides. 

Melting ice in the ground makes a new lake form where no lakes existed before (Zackenberg, Greenland
A new lake formed where no lakes existed before (Zackenberg, Greenland, photo Gustaf Hugelius).


Permafrost affects about one-quarter of land in the northern hemisphere. These frozen soils lock up carbon that has been accumulated in biomass over millennia, preventing its breakdown and keeping it out of the atmosphere. Permafrost soils store around 1600 billion tons of carbon, which is nearly twice the amount currently in the atmosphere. Unlike gradual thaw that affects mostly the surface and penetrates the ground slowly, abrupt permafrost thawing disrupts deeper carbon more rapidly. In addition, abrupt thaw releases more methane -- a stronger greenhouse gas than carbon dioxide -- than does gradual thaw.

“We know enough about these systems to determine that there are substantial potential climate effects from rapid thaw. But we still need more field-data to more accurately project where these changes will occur.”, says Gustaf Hugelius. 

The team discusses the importance of rapid collapse for carbon release estimates and global climate policy in a commentary in the May 2 issue of Nature. The researchers put together results from abrupt thaw studies from a range of environments across the permafrost zone to provide a first estimate of the overall effect. Results show that abrupt permafrost thawing affects less than 20 per cent of the permafrost region, but carbon emissions from this relatively small region have the potential to double the climate feedback associated with permafrost thawing.

In northern Sweden abrupt permafrost thaw has also been observed. “In Tavvavuoma the landscape, characterized by carbon-rich peatlands, changes rapidly. New lakes form when the ground collapses. Lakes grow in size, but also drain when the underlying or surrounding permafrost thaws,” says Britta Sannel.

“This report aims to address an important gap of knowledge to assess total releases of carbon from thawing permafrost, which is mentioned as a key uncertainty in the most recent IPCC report on keeping global warming at 1.5 °C”, stresses Peter Kuhry.

In their paper, the team calls for more measurement and monitoring of Arctic permafrost, as well as improved modelling and reporting of effects of thaw on climate. 

Despite threats to northern permafrost and climate, Turetsky remains optimistic. “If we can limit human emissions, we can still curb the most dangerous consequences of climate warming.  Our window for action is getting narrow, but we still have it and can make changes to save the Arctic as we know it, and the Earth’s climate along with it.”

The Comment was published in Nature 2 May; https://www.nature.com/magazine-assets/d41586-019-01313-4/d41586-019-01313-4.pdf

Reference
Turetsky, M.R., Abbott, B.W., Jones, M.C., Walter Anthony, K., Olefeldt, D., Schuur, E.A.G., Koven, C., McGuire, A.D., Grosse, G., Kuhry, P.,Hugelius, G., Lawrence, D.M., Gibson, C., Sannel, A.B.K., 2019: Permafrost collapse is accelerating carbon release. Nature569, 32-34.

Contact

Lead author:                                             
Dr. Merritt Turetsky, University of Guelph
Email: mrt@uoguelph.ca
Phone: +1-519-221-4043

Swedish co-authors:           
Dr. Gustaf Hugelius
Email: gustaf.hugelius@natgeo.su.se
Phone: +46-8-674 78 73

Prof. Peter Kuhry
Email: peter.kuhry@natgeo.su.se

Dr. Britta Sannel
Email: britta.sannel@natgeo.su.se
Phone: +46-8-16 47 95