New knowledge about permafrost improving climate models

New knowledge about permafrost improving climate models

Top image: Professor Bo Elberling (right) and AG-333 UNIS students obtaining a permafrost core from the ground moraine with heath vegetation in Zackenberg, North East Greenland in August 2008. Photo: Hanne H. Christiansen/UNIS. 

New findings from the Centre for Permafrost, CENPERM, document that permafrost during thawing may result in a substantial release of carbon dioxide into the atmosphere, and that the future water content primarily controlled by the permafrost ice content is crucial to predict the effect of permafrost thawing. The findings may lead to more accurate climate models in the future.

30 July 2013
Press release from University of Copenhagen and UNIS

The research results, from an international team coordinated from the Centre for Permafrost, CENPERM, at the Department of Geosciences and Natural Resource Management, University of Copenhagen, were published Sunday 28 July in Nature Climate Change.

Read the Nature Climate Change abstract here

Thawing permafrost contributes to the release of carbon dioxide and other greenhouse gases into the atmosphere. But the rate at which carbon dioxide is released from permafrost is poorly documented, and is one of the most important uncertainties of the current climate models.

First long-term study
The knowledge available so far has primarily been based on measurements of the release of carbon dioxide in short-term studies of up to 3-4 months. The new findings are based on measurements carried out over a 12-year period. Studies from different landforms with different permafrost ice content producing different water content have also been conducted.

– From a climate change perspective, it makes a huge difference whether it takes 10 or 100 years to release e.g. half the permafrost carbon pool. We have demonstrated that the supply of oxygen in connection with drainage or drying is essential for a rapid release of carbon dioxide into the atmosphere, says professor Bo Elberling, Director of CENPERM, Centre for Permafrost, University of Copenhagen and adjunct professor at the University Centre in Svalbard (UNIS).

The new findings also show that the future water content in the soil is a decisive factor for being able to correctly predict the effect of permafrost thawing. If the permafrost remains water-saturated after thawing, the carbon decomposition rate will be very low, and the release of carbon dioxide will take place over several hundred years, in addition to methane that is produced in waterlogged conditions. The findings can be used directly to improve existing climate models.

Sampling from Greenland, Svalbard and Canada
The new studies are mainly conducted at the Zackenberg research station in North-East Greenland, but permafrost samples from four other locations in Svalbard and in Canada have also been included and they show a surprising similarity in the loss of carbon over time.

– It is thought-provoking that microorganisms are behind the entire problem – microorganisms which break down the carbon pool and which are apparently already present in the permafrost. One of the critical decisive factors – the water content – is in the same way linked to the original high content of ice in most permafrost samples. Yes, the temperature is increasing, and the permafrost is thawing, but it is, still, the characteristics of the permafrost which determine the long-term release of carbon dioxide, Bo Elberling concludes.

UNIS professor Hanne Christiansen has been involved in designing the active layer monitoring sites of two different landforms in 1996 in North East Greenland, and she, Bo Elberling and students of the IPY course AG-333 performed the permafrost hand drillings both in Svalbard and North East Greenland in 2008.

– It is very good to see how the combination of long-term active layer observation data, and data on ice content from permafrost sediment cores collected in different permafrost landforms, can significantly improve our understanding of how permafrost landscapes can be reacting to climatic variability, says professor Hanne Christiansen.

Zackenberg, NE Greenland

AG-333 students drilling into the wet grassland below a snow patch site in Zackenberg, August 2008. Photo: Hanne H. Christiansen/UNIS.

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