Modelling of long-term permafrost evolution in the discontinuous permafrost zone of North-West Siberia

2020 ◽  
Author(s):  
Ekaterina Ezhova ◽  
Ilmo Kukkonen ◽  
Elli Suhonen ◽  
Olga Ponomareva ◽  
Andrey Gravis ◽  
...  
Keyword(s):  
Snow Cover ◽  
Warm Season ◽  
Thermal Conditions ◽  
West Siberia ◽  
The Arctic ◽  
High Porosity ◽  
Permafrost Degradation ◽  
North West ◽  
Discontinuous Permafrost

<p>The rate of climate warming in North-West Siberia is among the highest in the world and this trend is especially pronounced in summer [1]. Analysis of permafrost thermal conditions in this area provides plausible scenarios of permafrost degradation also elsewhere. An increase in the summer mean temperature together with the prolongation of the warm season results in the increase of the thawing degree-days enhancing thawing of permafrost. Here we present the results of decadal temperature observations from three boreholes near Nadym, North-West Siberia. We further use the results and the observed cryolithological structure of soils in two boreholes to model the long-term evolution of the deep permafrost under two climate scenarios, RCP2.6 (climate action, fast reduction of CO<sub>2 </sub>emissions) and RCP8.5 (‘business as usual’). Both borehole sites have a topmost high-porosity, high-ice content layer of peat which helps prolonging the degradation. The main difference between the boreholes is snow cover resulting from the difference of borehole positions (one is located on the top of the hill). Our results suggest that under RCP8.5 scenario permafrost will degrade in both boreholes. On the contrary, under RCP2.6 scenario permafrost will degrade in one borehole with the deeper snow cover, where it already shows the signs of degradation. For the other borehole, the model predicts that permafrost will not degrade within the next 300 years, although the permafrost temperatures are eventually above -1°C.</p><p>[1] Frey K.E. & Smith L.C. Recent temperature and precipitation increases in West Siberia and their association with the Arctic Oscillation. Polar Research <strong>22(2)</strong>, 287–300 (2003).</p>

Soil organic carbon along a geothermal gradient in North-West Canada

2020 ◽  
Author(s):  
Tino Peplau ◽  
Edward Gregorich ◽  
Christopher Poeplau
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Forest Ecosystem ◽  
Hot Springs ◽  
Negative Relationship ◽  
Geothermal Gradient ◽  
Soil Warming ◽  
North West ◽  
Discontinuous Permafrost

<p>Global warming will increase soil microbial activity and thus catalyse the mineralisation of soil organic carbon (SOC). Predicting the dynamics of soil organic carbon in response to warming is crucial but associated with large uncertainties, owing to experimental limitations. Most studies use in-vitro incubation experiments or relatively short-term in-situ soil warming experiments. Long-term observations on the consequences of soil warming on whole-profile SOC are still rare. Here, we used a long-term geothermal gradient in North-West Canada to study effects of warming on quantity and quality of SOC in an aspen forest ecosystem.</p><p>The Takhini hot springs are located within the region of discontinuous permafrost in the southern Yukon Territory, Canada. The springs warm the surrounding soil constantly and lead to a horizontal temperature gradient of approximately 10°C within a radius of 100 meters. As these natural springs heat the ground for centuries and the forest ecosystem surrounding the springs is relatively homogenous, the site provides ideal conditions for observing long-term effects of soil warming on ecosystem properties. Soils were sampled at four different warming intensities to a depth of 80 cm and analysed for their SOC content and further soil properties in different depths. </p><p>For the bulk soil, we found a significant negative relationship between soil temperature and SOC stocks. This confirms that climate change will most likely induce SOC loss and thus a positive climate- carbon cycle feedback loop. The response of five different SOC fractions to warming will also be presented.</p>

scholarly journals Biannual cycles of organochlorine pesticide enantiomers in arctic air suggest changing sources and pathways

2014 ◽  
Vol 14 (17) ◽  
pp. 25027-25050
Author(s):  
T. F. Bidleman ◽  
L. M. Jantunen ◽  
H. Hung ◽  
J. Ma ◽  
G. A. Stern ◽  
...  
Keyword(s):  
Warm Season ◽  
Open Water ◽  
Cold Season ◽  
Secondary Emission ◽  
Air Monitoring ◽  
The Arctic ◽  
Gas Chromatography Mass Spectrometry ◽  
Digital Filtration ◽  
Specific Analysis

Abstract. Air samples collected during 1994–2000 at the Canadian arctic air monitoring station Alert (82°30' N, 62°20' W) were analyzed by enantiospecific gas chromatography – mass spectrometry for α-hexachlorocyclohexane (α-HCH), trans-chlordane (TC) and cis-chlordane (CC). Results were expressed as enantiomer fractions (EF = quantities of (+)/[(+) + (−)] enantiomers), where EFs = 0.5, <0.5 and >0.5 indicate racemic composition, and preferential depletion of (+) and (−) enantiomers, respectively. Long-term average EFs were close to racemic values for α-HCH (0.504 ± 0.004, n = 197) and CC (0.505 ± 0.004, n = 162), and deviated farther from racemic for TC (0.470 ± 0.013, n = 165). Digital filtration analysis revealed biannual cycles of lower α-HCH EFs in summer-fall and higher EFs in winter-spring. These cycles suggest volatilization of partially degraded α-HCH with EF < 0.5 from open water and advection to Alert during the warm season, and background transport of α-HCH with EF > 0.5 during the cold season. The contribution of sea-volatilized α-HCH was only 11% at Alert, vs. 32% at Resolute Bay (74.68° N, 94.90° W) in 1999. EFs of TC also followed biannual cycles of lower and higher values in the warm and cold seasons. These were in phase with low and high cycles of the TC/CC ratio (expressed as FTC = TC/(TC + CC)), which suggests greater contribution of microbially "weathered" TC in summer-fall vs. winter-spring. CC was closer to racemic than TC and displayed seasonal cycles only in 1997–1998. EF profiles are likely to change with rising contribution of secondary emission sources, weathering of residues in the environment, and loss of ice cover in the Arctic. Enantiomer-specific analysis could provide added forensic capability to air monitoring programs.

scholarly journals Application of New Precipitation and Reconstructed Streamflow Products to Streamflow Trend Attribution in Northern Eurasia

2008 ◽  
Vol 21 (8) ◽  
pp. 1807-1828 ◽  
Author(s):  
Jennifer C. Adam ◽  
Dennis P. Lettenmaier
Keyword(s):  
River Discharge ◽  
Low Frequency ◽  
The Arctic ◽  
Northern Eurasia ◽  
Permafrost Degradation ◽  
Northeastern Siberia ◽  
Physically Based ◽  
Streamflow Trends ◽  
Precipitation Trends

Abstract River runoff to the Arctic Ocean has increased over the last century, primarily during the winter and spring and primarily from the major Eurasian rivers. Some recent studies have suggested that the additional runoff is due to increased northward transport of atmospheric moisture (and associated increased precipitation), but other studies show inconsistencies in long-term runoff and precipitation trends, perhaps partly due to biases in the observational datasets. Through trend analysis of precipitation, temperature, and streamflow data, the authors investigate the extent to which Eurasian Arctic river discharge changes are attributable to precipitation and temperature changes as well as to reservoir construction and operation between the years of 1936 and 2000. Two new datasets are applied: a gridded precipitation product, in which the low-frequency variability is constrained to match that of long-term bias-corrected precipitation station data, and a reconstructed streamflow product, in which the effects of reservoirs have been minimized using a physically based reservoir model. It is found that reservoir operations have primarily affected streamflow seasonality, increasing winter discharge and decreasing summer discharge. To understand the influences of climate on streamflow changes, the authors hypothesize three cases that would cause precipitation trends to be inconsistent with streamflow trends: first, for the coldest basins in northeastern Siberia, streamflow should be sensitive to warming primarily as a result of the melting of excess ground ice, and for these basins positive streamflow trends may exceed precipitation trends in magnitude; second, evapotranspiration (ET) in the warmer regions of western Siberia and European Russia is sensitive to warming and increased precipitation, therefore observed precipitation trends may exceed streamflow trends; and third, streamflow from the central Siberian basins should respond to both effects. It is found that, in general, these hypotheses hold true. In the coldest basins, streamflow trends diverged from precipitation trends starting in the 1950s to 1960s, and this divergence accelerated thereafter. In the warmest basins, precipitation trends consistently exceeded streamflow trends, suggesting that increased precipitation contributed to increases in both ET and streamflow. In the central basins, permafrost degradation and ET effects appear to be contributing to long-term streamflow trends in varying degrees for each basin. The results herein suggest that the extent and state of the permafrost underlying a basin is a complicating factor in understanding long-term changes in Eurasian Arctic river discharge.

Establishment of Warm- and Cool-Season Native Perennial Grasses on the North-West Slopes of New South Wales. I. Dormancy and Germination

1981 ◽  
Vol 29 (2) ◽  
pp. 111 ◽  
Author(s):  
GM Lodge ◽  
RDB Whalley
Keyword(s):  
New South ◽  
Warm Season ◽  
Perennial Grasses ◽  
Cool Season ◽  
North West ◽  
The North ◽  
South Wales ◽  
High Germination ◽  
Ecological Implications

The dormancy and germination of two groups of native perennial grasses were investigated in caryopses or dispersal units. The species were the warm-season native perennial grasses Aristida ramosa R.Br., Bothriochloa macra (Steud.) S. T . Blake. Dichanthium sericeum (R.Br.) Camus, Sporobolus elongatus R.Br., Eragrostis leptostachya Steud., Chloris truncata R.Br. and the cool-season species Stipa variabilis Hughes and Danthonia linkii Kunth. Optimum temperatures for germination were 20-35°C for A . ramosa; 15-35° for D. sericeum and C. Truncata; 20-25° for E. leptostachya; 20-30° for B. macra and S. elongatus and 15-25° for D. linkii and S . Variabilis. At 1O° and 40° D. linkii and A. ramosa respectively were the only species that had high germination percentages. Removal of the lemma and palea from freshly harvested units of A. ramosa, B. macra, D. sericeum, C. Truncata and S. variabilis significantly increased germination. In units stored at 12-27°C there was a breakdown in dormancy after 2-3 months in A. ramosa and B. macra and after 9 months in S. elongatus. In the germination of D. sericeum and D. linkii the lemma and palea appeared to have a long-term inhibitory role. Twenty-week-old whole dispersal units of B. macra, S. elongatus and E. leptostachya and 40-week-old units of S. elongatus and E. leptostachya had an obligate light requirement for germination. The ecological implications of these data in the successful germination of natural seed falls and artificial seedings are discussed.

scholarly journals Ecosystem changes across a gradient of permafrost degradation in subarctic Québec (Tasiapik Valley, Nunavik, Canada)

2019 ◽  
Vol 5 (1) ◽  
pp. 1-26 ◽  
Author(s):  
Maude Pelletier ◽  
Michel Allard ◽  
Esther Levesque
Keyword(s):  
Snow Cover ◽  
Climate Warming ◽  
Organic Matter Content ◽  
Integrated Approach ◽  
Matter Content ◽  
Active Layer Thickness ◽  
Permafrost Degradation ◽  
Permafrost Thaw ◽  
Discontinuous Permafrost ◽  
Cover Thickness

Permafrost thaw, tundra shrubification, and changes in snow cover properties are documented impacts of climate warming, particularly in subarctic regions where discontinuous permafrost is disappearing. To obtain some insight into those changes, permafrost, active layer thickness, vegetation, snow cover, ground temperature, soil profiles, and carbon content were surveyed in an integrated approach in six field plots along a chronosequence of permafrost thaw on an ice-rich silty soil. Historical air photographs and dendrochronology provided the chronological context. Comparison of the plots reveals a positive feedback effect between thaw settlement, increased snow cover thickness, shrub growth, increase in soil temperature, and the process of permafrost decay. By the end of the sequence permafrost was no longer sustainable. Along the estimated 90 year duration of the chronosequence, the originally centimeter-thin pedogenic horizons under mosses and lichens increased to a thickness of nearly 65 cm under shrubs and trees. Snow cover increased from negligible to over 2 m. The thickness of soil organic layers and soil organic matter content increased manyfold, likely a result of the increased productivity in the shrub-dominated landscape. The results of this study strongly suggest that permafrost ecosystems in the subarctic are being replaced under climate warming by shrub and forest ecosystems enriched in carbon on more evolved soils.

scholarly journals Long-term monitoring reveals topographical features and vegetation explain winter habitat use of an Arctic rodent

2021 ◽  
Author(s):  
Xaver von Beckerath ◽  
Gita Benadi ◽  
Olivier Gilg ◽  
Benoît Sittler ◽  
Glenn Yannic ◽  
...  
Keyword(s):  
Global Warming ◽  
Habitat Use ◽  
Snow Cover ◽  
Food Plants ◽  
The Arctic ◽  
Vegetation Types ◽  
Winter Habitat ◽  
Habitat Features ◽  
Terrestrial Vertebrates

AbstractCollapsing lemming cycles have been observed across the Arctic, presumably due to global warming creating less favorable winter conditions. The quality of wintering habitats, such as depth of snow cover, plays a key role in sustaining population dynamics of arctic lemmings. However, few studies so far investigated habitat use during the arctic winter. Here, we used a unique long-term time series to test whether lemmings are associated with topographical and vegetational habitat features for their winter refugi. We examined yearly numbers and distribution of 22,769 winter nests of the collared lemming Dicrostonyx groenlandicus from an ongoing long-term research on Traill Island, Northeast Greenland, collected between 1989 and 2019, and correlated this information with data on dominant vegetation types, elevation and slope. We specifically asked if lemming nests were more frequent at sites with preferred food plants such as Dryas octopetala x integrifolia and at sites with increased snow cover. We found that the number of lemming nests was highest in areas with a high proportion of Dryas heath, but also correlated with other vegetation types which suggest some flexibility in resource use of wintering lemmings. Conversely, they showed a distinct preference for sloped terrain, probably as it enhances the formation of deep snow drifts which increases the insulative characteristics of the snowpack and protection from predators. With global warming, prime lemming winter habitats may become scarce through alteration of snow physical properties, potentially resulting in negative consequence for the whole community of terrestrial vertebrates.

Development of Long-Term Satellite-Based Snow Mass Records in the ESA Snow CCI Project

2020 ◽  
Author(s):  
Kari Luojus ◽  
Matias Takala ◽  
Jouni Pulliainen ◽  
Juha Lemmetyinen ◽  
Mikko Moisander ◽  
...  
Keyword(s):  
Snow Cover ◽  
Northern Hemisphere ◽  
Snow Water Equivalent ◽  
Reliable Information ◽  
The Arctic ◽  
Climate Research ◽  
Data Record ◽  
Snow Water ◽  
Snow Mass

&lt;p&gt;Reliable information on snow cover across the Northern Hemisphere and Arctic and sub-Arctic regions is needed for climate monitoring, for understanding the Arctic climate system, and for the evaluation of the role of snow cover and its feedback in climate models. In addition to being of significant interest for climatological investigations, reliable information on snow cover is of high value for the purpose of hydrological forecasting and numerical weather prediction. Terrestrial snow covers up to 50 million km&amp;#178; of the Northern Hemisphere in winter and is characterized by high spatial and temporal variability making satellite observations the only means for providing timely and complete observations of the global snow cover. The ESA Snow CCI project was initiated in 2018 to improve methodologies for snow cover extent (SE) and snow water equivalent (SWE) retrieval [1] using satellite data and construct long term data records of terrestrial snow cover for climate research purposes.&lt;/p&gt;&lt;p&gt;The first new long term SWE data record from the ESA Snow CCI project, spanning 1979 to 2018 has been constructed and assessed in terms of retrieval performance, homogeneity and temporal stability. The initial results show that the new SWE dataset is more robust, more accurate and more consistent over the 40-year time series, compared to the earlier ESA GlobSnow SWE v1.0 and v2.0 data records [1].&lt;/p&gt;&lt;p&gt;The improved SWE retrieval methodology incorporates a new emission model (within the retrieval scheme), an improved synoptic weather station snow depth data record (applied to support SWE retrieval), extension of the SWE retrieval to cover the whole Northern Hemisphere.&lt;/p&gt;&lt;p&gt;The new Snow CCI SWE data record has been used to assess changes in the long term hemispherical snow conditions and climatological trends in Northern Hemisphere, Eurasia and North America. The general finding is that the peak hemispherical snow mass during the satellite era has not yet decreased significantly but has remained relatively stable, with changes to lower and higher SWE conditions in different geographical regions.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;[1] Takala, M, K. Luojus, J. Pulliainen, C. Derksen, J. Lemmetyinen, J.-P. K&amp;#228;rn&amp;#228;, J. Koskinen, B. Bojkov. 2011. Estimating northern hemisphere snow water equivalent for climate research through assimilation of space-borne radiometer data and ground-based measurements. Remote Sensing of Environment, 115, 12, 3517-3529, doi:10.1016/j.rse.2011.08.014.&lt;/p&gt;

Observations and modelling of ground temperature evolution in the discontinuous permafrost zone in Nadym, north‐west Siberia

2020 ◽  
Vol 31 (2) ◽  
pp. 264-280
Author(s):  
Ilmo T. Kukkonen ◽  
Elli Suhonen ◽  
Ekaterina Ezhova ◽  
Hanna Lappalainen ◽  
Victor Gennadinik ◽  
...  
Keyword(s):  
West Siberia ◽  
Ground Temperature ◽  
Permafrost Zone ◽  
Temperature Evolution ◽  
North West ◽  
Discontinuous Permafrost
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