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  • 1
    Publication Date: 2017-02-08
    Description: Approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafrost zone, more than twice as much C than in the atmosphere. The overall amount, rate, and form of C released to the atmosphere in a warmer world will influence the strength of the permafrost C feedback to climate change. We used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change. Experts were asked to provide quantitative estimates of permafrost change in response to four scenarios of warming. For the highest warming scenario (RCP 8.5), experts hypothesized that C release from permafrost zone soils could be 19–45 Pg C by 2040, 162–288 Pg C by 2100, and 381–616 Pg C by 2300 in CO2 equivalent using 100-year CH4 global warming potential (GWP). These values become 50 % larger using 20-year CH4 GWP, with a third to a half of expected climate forcing coming from CH4 even though CH4 was only 2.3 % of the expected C release. Experts projected that two-thirds of this release could be avoided under the lowest warming scenario (RCP 2.6). These results highlight the potential risk from permafrost thaw and serve to frame a hypothesis about the magnitude of this feedback to climate change. However, the level of emissions proposed here are unlikely to overshadow the impact of fossil fuel burning, which will continue to be the main source of C emissions and climate forcing.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 2
    Publication Date: 2016-10-13
    Description: Thermokarst is the process whereby the thawing of ice-rich permafrost ground causes land subsidence, resulting in development of distinctive landforms. Accelerated thermokarst due to climate change will damage infrastructure, but also impact hydrology, ecology and biogeochemistry. Here, we present a circumpolar assessment of the distribution of thermokarst landscapes, defined as landscapes comprised of current thermokarst landforms and areas susceptible to future thermokarst development. At 3.6 × 106 km2, thermokarst landscapes are estimated to cover ∼20% of the northern permafrost region, with approximately equal contributions from three landscape types where characteristic wetland, lake and hillslope thermokarst landforms occur. We estimate that approximately half of the below-ground organic carbon within the study region is stored in thermokarst landscapes. Our results highlight the importance of explicitly considering thermokarst when assessing impacts of climate change, including future landscape greenhouse gas emissions, and provide a means for assessing such impacts at the circumpolar scale.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed , info:eu-repo/semantics/article
    Format: application/pdf
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  • 3
    Publication Date: 2016-12-13
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 4
    Publication Date: 2015-04-10
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed , info:eu-repo/semantics/article
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  • 5
    Publication Date: 2019-05-17
    Description: The high latitudes form an important component of the Earth’s carbon cycle. It is therefore important to capture this in Earth System Models (ESM’s). However, most carbon-cycle development and evaluation in ESM’s focuses on lower latitudes, and therefore there is an urgent need to address Arctic carbon-cycle processes. Here, we run land-surface schemes from ESM’s at the site level at various Arctic sites, performing a detailed evaluation of the carbon dynamics in the models. They are process-based models, and therefore point-scale evaluations contribute directly towards improving the large-scale results. The sites chosen for the simulations are the five principal field sites from the recently-concluded EU project PAGE21. This gives the distinct advantage that detailed data are available. In particular, data on the physical state of the climate and permafrost at these sites, and large datasets of soil carbon stocks and fluxes. The sites cover a range from low Arctic discontinuous permafrost to high Arctic desert, and a range of soil types from thick peat to mineral soils with little organic matter. The models involved are land surface schemes from three European ESM’s: UKESM (UK), IPSL (France) and MPI-ESM (Germany). The models all have improved process representation as part of PAGE21. The simulations are first compared with physical observations from the sites: specifically snow depth, soil temperature, soil moisture and maximum thaw depth. All models capture the physics with a reasonable accuracy, and certainly capture the major differences between sites, with a few exceptions. In particular, we see the importance of simulating the physical properties of the soil organic layer. Comparing simulated soil organic carbon with observations shows the importance of including vertical soil carbon profiles. In one model this is not represented, which results in a failure to capture the differences in soil carbon in different physical conditions. Including cryoturbation mixing is key to simulating the vertical soil organic carbon profile. When vertical mixing is included, the profile of soil organic carbon at mineral soil sites matches very well with observations. However, none of the models are able to simulate the correct profile at sites with organic soils, highlighting the need for further process representation of peat accumulation. Finally, the land-atmosphere carbon fluxes are assessed using different observations, and we discuss the meaning of these measurements in terms of the land surface model output and how they can be most usefully compared. The simulation of carbon fluxes depends on every aspect of the models: The physical state, the soil carbon stocks and most importantly, the vegetation. Large errors result from the models growing the wrong type of vegetation or no vegetation at all, as tundra vegetation types are not represented in two of the three models. Focussed work is required to better represent Arctic vegetation in such models, and our results highlight the next steps to take. The observational datasets are more detailed than those used in past studies and this work will be used both to facilitate and to justify the development of Arctic carbon cycle processes in Earth system models.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed , info:eu-repo/semantics/conferenceObject
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  • 6
    Publication Date: 2013-07-01
    Description: Approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafrost zone, more than twice as much C than in the atmosphere. The overall amount, rate, and form of C released to the atmosphere in a warmer world will influence the strength of the permafrost C feedback to climate change. We used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change. Experts were asked to provide quantitative estimates of permafrost change in response to four scenarios of warming. For the highest warming scenario (RCP 8.5), experts hypothesized that C release from permafrost zone soils could be 19–45 Pg C by 2040, 162–288 Pg C by 2100, and 381–616 Pg C by 2300 in CO2 equivalent using 100-year CH_4 global warming potential (GWP). These values become 50 % larger using 20-year CH_4 GWP, with a third to a half of expected climate forcing coming from CH_4 even though CH_4 was only 2.3 % of the expected C release. Experts projected that two-thirds of this release could be avoided under the lowest warming scenario (RCP 2.6). These results highlight the potential risk from permafrost thaw and serve to frame a hypothesis about the magnitude of this feedback to climate change. However, the level of emissions proposed here are unlikely to overshadow the impact of fossil fuel burning, which will continue to be the main source of C emissions and climate forcing. ©2013 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s10584-013-0730-7" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 0165-0009
    Electronic ISSN: 1573-1480
    Topics: Geosciences , Physics
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  • 7
    Publication Date: 2014-08-22
    Description: Forest and peatland ecosystems constitute the two major carbon pools in the boreal region. We assess the evolution in total storage and partitioning of ecosystem carbon following recent paludification of forest into peatland at two sites in Northeast European Russia. Based on radiocarbon dating of basal peat and quantification of total ecosystem carbon storage, our results show that paludification rates and its consequences for carbon storage vary significantly between sites. A peatland expanding on ground with steeper slopes has experienced a slow lateral advance in recent times, about 2.6 m on average per century, whereas a peatland in flatter terrain has expanded much more rapidly, about 35 m on average per century. The total ecosystem carbon storage (sum of phytomass, top soil organics or peat, and 30 cm of underlying mineral soil) showed a long-term trend toward increased ecosystem C storage following the replacement of forest (mean value = 20.8 kg C/m 2 , range = 13.0–43.4 kg C/m 2 ) by peatland (〉100 kg C/m 2 in the deepest peat deposits). However, the transitional stage in which the forest is replaced by the margin of the peatland results in a short-term decrease of carbon stored in the ecosystem with a mean loss of 7.5 kg C/m 2 . After the initiation of a peatland through paludification, a period of decades to centuries of peat accumulation is needed to compensate for the initial loss of carbon. In the short term, an intensification of the paludification process could lead to a loss of carbon stored in the boreal region.
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage
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  • 8
    Publication Date: 2013-09-06
    Description: The environment of the northern taiga to tundra transition is highly sensitive to climate fluctuations. In this study from northeastern European Russia, stable carbon and oxygen isotope ratios ( 13 C, 18 O) in α-cellulose of Sphagnum fuscum stems subsampled from hummocks and peat plateau profiles have been used as climate proxies. The entire isotope time series, dated by lead ( 210 Pb), caesium ( 137 Cs) and AMS-radiocarbon ( 14 C) dating, spans the past 2500 years. Plant macrofossil analyses were used as an aid in single species selection, but are also helpful in identifying past surface moisture conditions. The most significant relationships were found between the recent 13 C record and summer (July–August) temperatures ( R 2 = 0.58, p 〈 0.01), and the recent 18 O record and winter (October–May) precipitation anomalies in the tundra region ( R 2 = 0.36, p 〈 0.01). The study demonstrates that stable isotopes preserved in northern peat deposits are useful indicators for summer temperature and winter precipitation at decadal to millennial timescales.
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage
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  • 9
    Publication Date: 2013-12-23
    Description: High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of 18.7 × 106 km2). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to calculate SOC storage to the reference depths 0–30 cm and 0–100 cm (based on 1778 pedons). It has been shown that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100–300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m−2) in deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100–200 cm (524 pedons) and 200–300 cm (356 pedons) depth ranges. These pedons have been grouped into the North American and Eurasian sectors and the mean SOC storage for different soil taxa (subdivided into Gelisols including the sub-orders Histels, Turbels, Orthels, permafrost-free Histosols, and permafrost-free mineral soil orders) has been added to the updated NCSCDv2. The updated version of the data set is freely available online in different file formats and spatial resolutions that enable spatially explicit applications in GIS mapping and terrestrial ecosystem models. While this newly compiled data set adds to our knowledge of SOC in the 100–300 cm depth range, it also reveals that large uncertainties remain. Identified data gaps include spatial coverage of deep (〉 100 cm) pedons in many regions as well as the spatial extent of areas with thin soils overlying bedrock and the quantity and distribution of massive ground ice. An open access data-portal for the pedon data set and the GIS-data sets is available online at http://bolin.su.se/data/ncscd/. The NCSCDv2 data set has a digital object identifier (doi:10.5879/ECDS/00000002).
    Print ISSN: 1866-3508
    Electronic ISSN: 1866-3516
    Topics: Geosciences
    Published by Copernicus
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  • 10
    Publication Date: 2017-04-10
    Print ISSN: 1758-678X
    Electronic ISSN: 1758-6798
    Topics: Geosciences
    Published by Springer Nature
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