Special issue |
Changing Permafrost in the Arctic and its Global Effects in the 21st Century (PAGE21) (BG/ESSD/GMD/TC inter-journal SI)(BG/ESSD/GMD/TC inter-journal SI)
Editor(s): S. Gruber, J. Boike, and S. Lamoreux
Special issue jointly organized between Biogeosciences, Earth System Science Data, Geoscientific Model Development, and The Cryosphere
Permafrost is defined as ground that remains continuously at or below 0°C for at least two consecutive years; some 24% of the land surface in the Northern Hemisphere is classified as permafrost. In the northern high latitudes, strong warming has been observed over the recent decades, and climate models project strong future warming. A projected decline in the extent of permafrost will have a major impact on the Earth system, affecting global climate through the mobilization of carbon and nitrogen stored in permafrost. This special issue invites results of the large-scale European project PAGE21 with the aim to quantify the vulnerability of permafrost environments to a changing global climate, and to investigate the feedback mechanisms associated with increasing greenhouse gas emissions from permafrost zones. The focus is on (i) the combination of field mapping and measurements of permafrost landforms, ground ice content, processes, pools, and fluxes, with remote sensing data and global climate models at local, regional, and pan-Arctic scales, as well as (ii) advancing our understanding of permafrost processes at multiple scales, resulting in improvements in global numerical permafrost modeling.
Isabelle Gouttevin, Moritz Langer, Henning Löwe, Julia Boike, Martin Proksch, and Martin Schneebeli
The Cryosphere, 12, 3693–3717, https://doi.org/10.5194/tc-12-3693-2018,https://doi.org/10.5194/tc-12-3693-2018, 2018
Snow insulates the ground from the cold air in the Arctic winter, majorly affecting permafrost. This insulation depends on snow characteristics and is poorly quantified. Here, we characterize it at a carbon-rich permafrost site, using a recent technique that retrieves the 3-D structure of snow and its thermal properties. We adapt a snowpack model enabling the simulation of this insulation over a whole winter. We estimate that local snow variations induce up to a 6 °C spread in soil temperatures.
Chloé Largeron, Gerhard Krinner, Philippe Ciais, and Claire Brutel-Vuilmet
Geosci. Model Dev., 11, 3279–3297, https://doi.org/10.5194/gmd-11-3279-2018,https://doi.org/10.5194/gmd-11-3279-2018, 2018
Peatlands are widely present in boreal regions and contain large carbon stocks due to their hydrologic properties and high water content. We have enhanced the global land surface model ORCHIDEE by introducing boreal peatlands. These are considered as a new type of vegetation in the model, with specific hydrological properties for peat soil. In this paper, we focus on the representation of the hydrology of northern peatlands and on the evaluation of the hydrological impact of this implementation.
Christine Kroisleitner, Annett Bartsch, and Helena Bergstedt
The Cryosphere, 12, 2349–2370, https://doi.org/10.5194/tc-12-2349-2018,https://doi.org/10.5194/tc-12-2349-2018, 2018
Knowledge about permafrost extent is required with respect to climate change. We used borehole temperature records from across the Arctic for the assessment of surface status information (frozen or unfrozen) derived from space-borne microwave sensors for permafrost extent mapping. The comparison to mean annual ground temperature (MAGT) at the coldest sensor depth revealed that not only extent but also temperature can be obtained from C-band-derived surface state with a residual error of 2.22 °C.
Juri Palmtag, Stefanie Cable, Hanne H. Christiansen, Gustaf Hugelius, and Peter Kuhry
The Cryosphere, 12, 1735–1744, https://doi.org/10.5194/tc-12-1735-2018,https://doi.org/10.5194/tc-12-1735-2018, 2018
This study aims to improve the previous soil organic carbon and total nitrogen storage estimates for the Zackenberg area (NE Greenland) that were based on a land cover classification approach, by using geomorphological upscaling. The landform-based approach more correctly constrains the depositional areas in alluvial fans and deltas with high SOC and TN storage. This research emphasises the need to consider geomorphology when assessing SOC pools in mountain permafrost landscapes.
To support C exchange measurements, we examined plant and soil attributes in Siberian Arctic tundra. Our results illustrate a typical tundra ecosystem with great spatial variation. Mosses dominate plant biomass and control many soil attributes such as temperature, but variation in moss biomass is difficult to capture by remote sensing. This indicates challenges in spatial extrapolation of some of those plant and soil attributes that are relevant for regional ecosystem and global climate models.
We present year-round methane emissions from wetlands in Northeast Siberia that were simulated with a land surface model. Ground-based flux measurements from the same area were used for evaluation of the model results, finding a best agreement with the observations in the summertime emissions that take place in this region predominantly through plants. During winter, methane emissions through the snow contribute 4 % of the total annual methane budget, but these are still underestimated.
Large amounts of soil organic carbon are stored in the circumpolar permafrost region. This article aims to improve how we map this carbon. Typically the amount of soil organic carbon is estimated using soil or land cover maps. Here the amount of carbon is modeled using machine learning. This is done at a very fine spatial resolution of 1 × 1 m. This reveals a lot of small-scale landscape variability and underlines the importance of permafrost-related landforms vulnerable to a warming climate.
We describe the evolution of thaw slumps between 1952 and 2011 along the Yukon Coast, Canada, and calculate the contribution of the slumps to the carbon budget in this area. The number of slumps has increased by 73 % over the period. These slumps displaced more than 16 billion m3 of material and mobilized 146 t of carbon. This represents 0.6 % of the annual carbon flux released from shoreline retreat, which shows that the contribution of slumps to the nearshore carbon budget is non-negligible.
Julia Boike, Inge Juszak, Stephan Lange, Sarah Chadburn, Eleanor Burke, Pier Paul Overduin, Kurt Roth, Olaf Ippisch, Niko Bornemann, Lielle Stern, Isabelle Gouttevin, Ernst Hauber, and Sebastian Westermann
A 20-year data record from the Bayelva site at Ny-Ålesund, Svalbard, is presented on meteorology, energy balance components, surface and subsurface observations. This paper presents the data set, instrumentation, calibration, processing and data quality control. The data show that mean annual, summer and winter soil temperature data from shallow to deeper depths have been warming over the period of record, indicating the degradation and loss of permafrost at this site.
Christian Beer, Philipp Porada, Altug Ekici, and Matthias Brakebusch
The Cryosphere, 12, 741–757, https://doi.org/10.5194/tc-12-741-2018,https://doi.org/10.5194/tc-12-741-2018, 2018
Idealized model experiments demonstrate that, in addition to a gradual climate change, changing daily to weekly variability of meteorological variables and extreme events will also have an impact on mean annual ground temperature in high-latitude permafrost areas. In fact, results of the land surface model experiments show that the projected increase of variability of meteorological variables leads to cooler permafrost soil in contrast to an otherwise soil warming in response to climate change.
Mathias Göckede, Fanny Kittler, Min Jung Kwon, Ina Burjack, Martin Heimann, Olaf Kolle, Nikita Zimov, and Sergey Zimov
The Cryosphere, 11, 2975–2996, https://doi.org/10.5194/tc-11-2975-2017,https://doi.org/10.5194/tc-11-2975-2017, 2017
Shifts in hydrologic conditions will be a key factor for the sustainability of Arctic ecosystems under future climate change. Using a long-term manipulation experiment, we analyzed how energy exchange processes within a permafrost ecosystem react to sustained dry conditions. Changes in several important ecosystem characteristics lead to reduced evapotranspiration and increased sensible heat fluxes. Heat transfer into the soil was strongly reduced, keeping the permafrost colder.
Sarah E. Chadburn, Gerhard Krinner, Philipp Porada, Annett Bartsch, Christian Beer, Luca Belelli Marchesini, Julia Boike, Altug Ekici, Bo Elberling, Thomas Friborg, Gustaf Hugelius, Margareta Johansson, Peter Kuhry, Lars Kutzbach, Moritz Langer, Magnus Lund, Frans-Jan W. Parmentier, Shushi Peng, Ko Van Huissteden, Tao Wang, Sebastian Westermann, Dan Zhu, and Eleanor J. Burke
Earth system models (ESMs) are our main tools for understanding future climate. The Arctic is important for the future carbon cycle, particularly due to the large carbon stocks in permafrost. We evaluated the performance of the land component of three major ESMs at Arctic tundra sites, focusing on the fluxes and stocks of carbon.
We show that the next steps for model improvement are to better represent vegetation dynamics, to include mosses and to improve below-ground carbon cycle processes.
We employed an individual- and patch-based dynamic global ecosystem model to quantify long-term C accumulation rates and to assess the effects of historical and projected climate change on peatland C balances across the pan-Arctic. We found that peatlands in Scandinavia, Europe, Russia and central and eastern Canada will become C sources, while Siberia, far eastern Russia, Alaska and western and northern Canada will increase their sink capacity by the end of the 21st century.
Boreal lakes and wetland ponds have pronounced impacts on the global methane cycle. During field campaigns to West Siberian lakes, strong variations in the methane flux on both local and regional scales were observed, with significant emissions from southern taiga lakes. A newly constructed process-based model helps reveal what controls this variability and on what spatial scales. Our results provide insights into the emissions and possible ways to significantly improve global carbon models.
We collected peat porewaters across a 640 km latitudinal transect of sporadic to continuous permafrost zone and analyzed organic carbon and trace metals. There was no distinct decrease in concentration along the latitudinal transect from 62.2° N to 67.4° N. The northward migration of the permafrost boundary or the change of hydrological regime is unlikely to modify chemical composition of peat porewater fluids larger than their natural variation within different micro-landscapes.
There are large reserves of carbon within the permafrost which might be released to the atmosphere under global warming. Our models suggest this release may cause an additional global temperature increase of 0.005 to 0.2°C by the year 2100 and 0.01 to 0.34°C by the year 2300. Under climate mitigation scenarios this is between 1.5 and 9 % (by 2100) and between 6 and 16 % (by 2300) of the global mean temperature change. There is a large uncertainty associated with these results.
Sina Muster, Kurt Roth, Moritz Langer, Stephan Lange, Fabio Cresto Aleina, Annett Bartsch, Anne Morgenstern, Guido Grosse, Benjamin Jones, A. Britta K. Sannel, Ylva Sjöberg, Frank Günther, Christian Andresen, Alexandra Veremeeva, Prajna R. Lindgren, Frédéric Bouchard, Mark J. Lara, Daniel Fortier, Simon Charbonneau, Tarmo A. Virtanen, Gustaf Hugelius, Juri Palmtag, Matthias B. Siewert, William J. Riley, Charles D. Koven, and Julia Boike
Waterbodies are abundant in Arctic permafrost lowlands. Most waterbodies are ponds with a surface area smaller than 100 x 100 m. The Permafrost Region Pond and Lake Database (PeRL) for the first time maps ponds as small as 10 x 10 m. PeRL maps can be used to document changes both by comparing them to historical and future imagery. The distribution of waterbodies in the Arctic is important to know in order to manage resources in the Arctic and to improve climate predictions in the Arctic.
Graham L. Gilbert, Stefanie Cable, Christine Thiel, Hanne H. Christiansen, and Bo Elberling
The Cryosphere, 11, 1265–1282, https://doi.org/10.5194/tc-11-1265-2017,https://doi.org/10.5194/tc-11-1265-2017, 2017
We reconstruct the Holocene development of the Zackenberg River delta (northeast Greenland) using a combination of sedimentology, cryostratigraphy, and geochronology. We distinguish four major depositional environments and identify three cryofacies. We apply the principles of cryostratigraphy to infer the aggradational history of permafrost. This paper contains an archive of ground ice in epigenetic permafrost in northeast Greenland.
Carina Schuh, Andrew Frampton, and Hanne Hvidtfeldt Christiansen
The Cryosphere, 11, 635–651, https://doi.org/10.5194/tc-11-635-2017,https://doi.org/10.5194/tc-11-635-2017, 2017
This study investigates how soil moisture retention characteristics impact ice and moisture redistribution, heat transport and active layer thickness under permafrost conditions. This is relevant for understanding how climate change interacts with permafrost, which is important because there is much stored carbon in permafrost, which may be released to the atmosphere as permafrost degrades and may then act to further enhance climate warming.
Eleanor J. Burke, Sarah E. Chadburn, and Altug Ekici
Geosci. Model Dev., 10, 959–975, https://doi.org/10.5194/gmd-10-959-2017,https://doi.org/10.5194/gmd-10-959-2017, 2017
There is a large amount of relatively inert organic carbon locked into permafrost soils. In a warming climate the permafrost will thaw and this organic carbon will become vulnerable to decomposition. This process is not typically included within Earth system models (ESMs). This paper describes the development of a vertically resolved soil organic carbon decomposition model which, in the future, can be included within the UKESM to quantify the response of the climate to permafrost carbon loss.
Sonja Kaiser, Mathias Göckede, Karel Castro-Morales, Christian Knoblauch, Altug Ekici, Thomas Kleinen, Sebastian Zubrzycki, Torsten Sachs, Christian Wille, and Christian Beer
Geosci. Model Dev., 10, 333–358, https://doi.org/10.5194/gmd-10-333-2017,https://doi.org/10.5194/gmd-10-333-2017, 2017
A new consistent, process-based methane module that is integrated with permafrost processes is presented. It was developed within a global land surface scheme and evaluated at a polygonal tundra site in Samoylov, Russia. The calculated methane emissions show fair agreement with field data and capture detailed differences between the explicitly modelled gas transport processes and in the gas dynamics under varying soil water and temperature conditions during seasons and on different microsites.
William L. Cable, Vladimir E. Romanovsky, and M. Torre Jorgenson
The Cryosphere, 10, 2517–2532, https://doi.org/10.5194/tc-10-2517-2016,https://doi.org/10.5194/tc-10-2517-2016, 2016
Permafrost temperatures in Alaska are increasing, yet in many areas we lack data needed to assess future changes and potential risks. In this paper we show that classifying the landscape into landcover types is an effective way to scale up permafrost temperature data collected from field monitoring sites. Based on these results, a map of mean annual ground temperature ranges at 1 m depth was produced. The map should be useful for land use decision making and identifying potential risk areas.
The Cryosphere, 10, 2291–2315, https://doi.org/10.5194/tc-10-2291-2016,https://doi.org/10.5194/tc-10-2291-2016, 2016
Bryophyte and lichen cover on the forest floor at high latitudes insulates the ground and thus decreases soil temperature. This can protect permafrost soil, stabilising it against global warming. To quantify the insulating effect, we integrate a novel, process-based model of bryophyte and lichen growth into the global land surface model JSBACH. We find an average cooling effect of the bryophyte and lichen cover of 2.7 K, which implies a significant impact on soil temperature at high latitudes.
A new approach for the estimation of soil organic carbon (SOC) pools north of the tree line has been developed based on synthetic aperture radar (SAR) data from the ENVISAT satellite. It can be shown that measurements of C-band SAR under frozen conditions represent vegetation and surface structure properties which relate to soil properties, specifically SOC. The approach provides the first spatially consistent account of soil organic carbon across the Arctic.
We compared growing season CO2 fluxes of a wet tussock tundra ecosystem from an area affected by decadal drainage and an undisturbed area on the Kolyma floodplain in northeastern Siberia. The results show systematically reduced CO2 uptake within the drained area, caused by increased respiration, and that the local permafrost ecosystem is capable of adapting to significantly different hydrologic conditions without losing its capacity to act as a net sink for CO2.
A decade-long drainage on an Arctic floodplain has altered dominant plant species and soil temperature regimes. Consequently, CO2 exchange rates between the atmosphere and the terrestrial ecosystem were modified: CO2 uptake rates by the terrestrial ecosystem decreased and CO2 emission rates to the atmosphere increased. Ongoing global warming may thaw ice-rich permafrost and make some regions drier in the Arctic, and this will reduce carbon accumulation in the terrestrial ecosystem.
The authors introduce the new database of the Global Terrestrial Network for Permafrost (GTN-P) on permafrost temperature and active layer thickness data. They describe the operability of the Data Management System and the data quality. By applying statistics on GTN-P metadata, they analyse the spatial sample representation of permafrost monitoring sites. Comparison with environmental variables and climate projection data enable identification of potential future research locations.