Published in Nature, 2017

75-year-old aerial photos reveal that Greenlandic deltas have grown as a result of the warmer climate

According to a new study from the University of Copenhagen, the Greenlandic deltas have been expanding as a result of the warmer climate Photo credit: Anders Anker Bjørk.

Deltas are important ecosystems, where freshwater meets the sea, and where people for centuries have been engaged in agriculture and fishing. Today, most of the deltas in the world are drowning because of increased human exploitation and a rise in the global sea level. In an article just published in Nature, a research team led by the Centre for Permafrost at the Department of Geosciences and Natural Resource Management at the University of Copenhagen has shown that deltas in Greenland, unlike most other deltas, are growing. Read more.

Mette Bendixen, Lars Lønsmann Iversen, Anders Anker Bjørk, Bo Elberling, Andreas Westergaard-Nielsen, Irina Overeem, Katy R. Barnhart, Shfaqat Abbas Khan, Jason E. Box, Jakob Abermann, Kirsty Langley & Aart Kroon (2017). Delta progradation in Greenland driven by increasing glacial mass loss Scientific. Nature, doi:10.1038/nature23873

Published in Scientific Reports, 2016

Long-distance transport of iron and sediments
A new study led by members of CENPERM, published in Scientific reports, Nature Publishing Group, show that sediments and nutrients can be transported surprisingly far in the marine environment.

Disko Fjord, in which the green seawater, full of algae, is mixed with the brown, iron- and<br>particle-rich meltwater. Photo Thor Nygaard Markussen

Disko Fjord, in which the green seawater, full of algae, is mixed with the brown, iron- and particle-rich meltwater.
Photo Thor Nygaard Markussen

It can affect how effectively the marine environment in the future can absorb carbon dioxide from the atmosphere. The results have been obtained by the researchers by use of a new particle camera developed in cooperation with the German research institution MARUM, Bremen. Read more.

Markussen, T.N., Elberling, B., Winter, C., Andersen, T.J. (2016). Flocculated meltwater particles control Arctic land-sea fluxes of labile iron. Scientific Reports 6, 24033.

Published in Nature Geoscience, 2016

Plant gasses can counteract arctic climate change
Plant gasses possibly dampen the temperature rise in Greenland. Plants emit compounds to deter pests or attract pollinators, and as a side effect particles are formed when the compounds interact in the air. These particles can contribute to the formation of clouds, which reflect incoming solar radiation, and thus prevent solar heat from reaching the ground and warming it additionally.                                                                 
Researchers measuring on the tiny tundra plants. Credit: Magnus Kramshøj

Researchers measuring on the tiny tundra plants.
Photo Magnus Kramshøj

Researchers from the University of Copenhagen have studied the effect of the imminent climate changes on the release of so-called “biogenic volatiles” to the atmosphere above Greenland. The sensational results are now being published in the prestigious scientific journal Nature Geoscience.
Read more.

Kramshøj, M., Vedel-Petersen, I., Schollert, M., Rinnan, Å., Nymand J., Ro-Poulsen, H., Rinnan, R. (2016). Large increases in Arctic biogenic volatile emissions are a direct effect of warming. Nature Geoscience 9, 349-352.

Published in Nature Climate Change, 2015

Climate sensitivity of shrub growth across the tundra biome
CENPERM has contributed to a new study synthesizing shrub growth data from 37 sites across the arctic tundra to explore spatial patterns in climate growth relationships.

The novel analyses in this study demonstrate that (1) the sensitivity of shrub growth is heterogeneous across the tundra biome, with shrubs in European sites showing greater sensitivity than shrubs growing in North American sites, and (2) the growth sensitivity to climate is stronger in sites with high soil moisture and tall shrubs.

The climate sensitivity of shrub growth was greatest at sites located at the boundary between Low and High Arctic, where permafrost is thawing and most of the global permafrost soil carbon pool is stored. The observed variation in climate–shrub growth relationships should be incorporated into Earth system models to improve future projections of climate change impacts across the tundra biome.

Myers-Smith, I.H, Elmendorf, S.C., Beck, P.S.A., Wilmking, M., Hallinger, M., Blok, D., … Vellend, M. (2015). Climate sensitivity of shrub growth across the tundra biome. Nature Climate Change 5,887-891.

Published in Nature Geoscience, 2015

Net regional methane sink in high arctic soils of northeast greenland
We conclude that the ice-free area of northeast Greenland acts as a net sink of atmospheric methane, and suggest that this sink will probably be enhanced in a future warmer climate.

Arctic tundra soils serve as potentially important but poorly understood sinks of methane which act as an important greenhouse gas in the atmosphere. Improved knowledge on methane consumption in the dominating dry arctic soils is needed in order to understand the total methane exchange budget in the High Arctic which is conceptually biased as being a net methane emitter. In this CENPERM publication, we present measurements of rates of methane consumption in different soil and vegetation types within the Zackenberg Valley in northeast Greenland. The results show a clear picture of methane uptake in all non-water-saturated landforms studied with higher uptake rates in drier soils.Methane oxidation rates was sensitive to increasing temperatures, indicating that future arctic warming could increase the overall importance of the High Arctic methane sink.

Extrapolation of our measurements and known wetlands fluxes using satellite based land cover classification, we conclude that the ice-free area of northeast Greenland acts as a net sink of atmospheric methane, and is likely to be increased in a future warmer climate.

Jørgensen, C.J., Johansen, K.M.L., Westergaard-Nielsen, A., Elberling, B. (2015). High Arctic CH4 sink reverses the CH4 budget of Northeast Greenland. Nature Geoscience 8, 20-23.

Dansk omtale (in Danish)

Published in Nature Climate Change, 2015

Arctic heating from within
Heat produced by Arctic soil microbes could enhance permafrost thaw and the release of carbon to the atmosphere, according to a paper published this week in Nature Climate Change.

The organic midden at Qajaa, West Greenland 
Køkkenmødding fra Qajaa i Vestgrønland
Photo by Bo Elberling

As global temperatures rise and permafrost thaws, the breakdown of organic material in the soil is expected to accelerate. The process by which this decomposition produces heat and may accelerate further thawing is not well understood.

”We have quantified microbial heat production in samples of organic permafrost soils collected from six sites across Greenland to investigate whether enough heat can be produced by enhanced activity to affect the rate of soil decomposition” tells professor Bo Elberling.

The model simulations reveal a feedback loop between soil temperatures and carbon decomposition that could accelerate rates of permafrost thaw and microbial heat production within the next 50-100 years. The study shows that this process can degrade evidence of early human activity in the Arctic, preserved in organic middens — archaeological features buried in the permafrost. The feedback loop seem to be important for organic middens in particular, and the results presented suggest that actions are needed to preserve these features in the future.

Hollesen, J., Matthiesen, H., Møller, A.B., Elberling, .B (2015). Permafrost thawing in organic Arctic soils accelerated by ground heat production. Nature Climate Change 5, 574-578.

Dansk omtale (in Danish)

Published in Nature Climate Change, 2014

Rapid permafrost collapse shifts siberian tundra to a methane source
Tundra ecosystems are undergoing rapid changes due to climatic changes, altering the vegetation composition and potentially destabilizing permafrost.  

Decomposition of buried plant and animal remains in permafrost soils could lead to further climate warming by release of greenhouse gases carbon dioxide and methane. We performed an experiment in the tundra of Fareast Siberia, a region known for its enormous permafrost carbon stores, whereby we removed the dominant shrub species dwarf birch ( Betula nana) to assess the effects on permafrost thaw. Surprisingly, the removal of shrubs led to a rapid incremental increase in summer permafrost thaw depth over the six years of the experiment. This deeper thaw led to a melt of ground-ice and collapse of the tundra surface, turning the original shrub mounds plots into ponds with standing water. The rapid and substantial changes in thaw depth, hydrology and surface elevation dramatically altered the methane-balance from a source to a sink of methane, just five years after the start of the experiment. These results show that plants play a crucial role in the stabilization of permafrost. Our experimental perturbations of plant cover, which can occur naturally due to e.g. insect outbreaks, fungal infections or changes in reindeer grazing pressure, demonstrate the fragility of tundra ecosystem under a climate warming scenario that can modify the tundra carbon balance and thus feedback to global climate changes.

Nauta, A.L., Heijmans, M.M.P.D., Blok, D., Limpens, J., Elberling, B., Gallagher, A., Li, B., Petrov, R.E., Maximov, T.C., van Huissteden, J., Berendse, F. (2014). Permafrost collapse after shrub removal shifts tundra ecosystem to a methane source. Nature Climate Change 5, 67-70.

Published in Nature Climate Change, 2013

Long-term co2 production following permafrost thaw
A group of CENPERM scie

ntists lead by Director Bo Elberling has revealed the importance of soil water content for long-term degradation of organic matter in thawed permafrost soil. The data are published in Nature Climate Change and are important for long-term projections of carbon dioxide emission from thawed permafrost.

Long-term CO2 production following permafrost thaw

Elberling, B., Michelsen, A., Schädel, C., Schuur, E.A.G., Christiansen, H.H., Berg, L., Tamstorf, M.P., Sigsgaard, C. (2013). Long-term CO2 production following permafrost thaw. Nature Climate Change 3, 890-894.

Mere information (in Danish)

Published in Nature Climate Change, 2012

Arctic vegetation is getting higher
Arctic vegetation is increasing in height and cover due to warming. New research published in Nature Climate Change shows that shrubs, grasses and forbs are getting taller while bare soil is reduced.

Arctic vegetation

Professor Anders Michelsen - photo by Sebrina Burchardt

In the circumpolar study, changes in vegetation structure and composition from 1980 to 2010 was recorded in 158 sites across the tundra, and related to observed temperature changes.

Elmendorf S, Henry G, Hollister RD, Björk R, Boulanger-Lapointe N, Cooper E, Cornelissen H, Day T, Dorrepaal E, Elumeeva T, Gill M, Gould W, Harte J, Hik D, Hofgaard A, Johnson DR, Johnstone JF, Jónsdóttir IS, Jorgenson JS, Klanderud K, Klein J, Koh S, Kudo G, Lara M, Lévesque E, Magnússon B, May J, Mercado-Diaz J, Michelsen et al. (2012). Plot-scale evidence of tundra vegetation change and links to recent summer warming. Nature Climate Change 2, 453–457.

Mere information (in Danish)