Future permafrost conditions along environmental gradients in Zackenberg, Greenland

Westermann, Sebastian; Elberling, Bo; Pedersen, Stine Højlund; Stendel, Martin; Hansen, Birger Ulf; Liston, Glen E.

doi:10.5194/tc-9-719-2015

Cited by 48 publications

(50 citation statements)

References 76 publications

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“…EC = electrical conductivity; Chl a = Chlorophyll a; -= no significant difference. the landscape leads to large spatial variation in ground thermal regime by snow cover acting as an insulator between ground and air (Westermann et al, 2015), leading to different permafrost degradation and active layer depth locally, and subjecting streams in close proximity to one another to different pressures based on local geomorphology. As well as snowfall, streams could see increased disturbance due to increased summer rain events.…”

Section: Variation In Environmental Habitat Conditionsmentioning

confidence: 99%

Spatio‐temporal dynamics of macroinvertebrate communities in northeast Greenlandic snowmelt streams

et al. 2018

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Future climate change throughout the Arctic is expected to increase channel stability in glacially influenced streams through reduced contributions from glacial meltwater and increases in groundwater. In contrast, predictions for northeast Greenland of increased precipitation for the next 100 years-including winter snowfall-which with warmer air temperature, is expected to increase the size of spring floods in snowmelt streams. Coupled with increased disturbance through frequent summer rainfall events, nivation processes and permafrost degradation will reduce resistance of channel sediments to erosion and thereby decrease channel stability. Decreased channel stability will impact macroinvertebrate abundance and diversity. Five streams sourced by snowpacks of varying extent were studied over 3 summer seasons (2013)(2014)(2015) to investigate the potential effect of shift in snowmelt regime on macroinvertebrate communities.Total abundance and taxa richness were significantly higher in streams with small snowpacks, where the chironomid genus Hydrobaenus was the most abundant taxon.Streams with large snowpacks were dominated by the chironomid genus Diamesa.Multivariate ordination models and correlation indicated that macroinvertebrate communities were significantly influenced by channel stability and bed sediment size.Macroinvertebrate abundance was significantly higher in 2013, following low winter snowfall and associated low meltwater inputs to streams, highlighting interannual variability in macroinvertebrate communities.A shift towards less stable habitats in snowmelt streams will potentially lead to reduced macroinvertebrate abundance and taxa richness, and local extinction of specialized taxa. Thus, snowmelt-fed streams in northeast Greenland may respond very differently to changing climate compared with streams in parts of the Arctic dominated by glacial meltwater. KEYWORDSArctic, channel stability, Chironomidae, climate change, freshwater, hydroecology, meltwater, snowThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Variation In Environmental Habitat Conditionsmentioning

confidence: 99%

Spatio‐temporal dynamics of macroinvertebrate communities in northeast Greenlandic snowmelt streams

et al. 2018

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“…While permafrost-specific models have made progress towards correctly simulating permafrost dynamics (Riseborough et al, 2008;Jafarov et al, 2012;Westermann et al, 2015), in global land-surface models the Arctic has often been neglected, leading to the large discrepancies between models and reality seen in Koven et al (2012). One reason that the NHLs are poorly represented in global models is the difficulty of obtaining observations with which to drive and evaluate the models.…”

Section: S Chadburn Et Al: Improved Physical Permafrost Dynamics Inmentioning

confidence: 99%

An improved representation of physical permafrost dynamics in the JULES land-surface model

Chadburn

Burke

Essery³

et al. 2015

Geosci. Model Dev.

102

116

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Abstract.It is important to correctly simulate permafrost in global climate models, since the stored carbon represents the source of a potentially important climate feedback. This carbon feedback depends on the physical state of the permafrost. We have therefore included improved physical permafrost processes in JULES (Joint UK Land Environment Simulator), which is the land-surface scheme used in the Hadley Centre climate models.The thermal and hydraulic properties of the soil were modified to account for the presence of organic matter, and the insulating effects of a surface layer of moss were added, allowing for fractional moss cover. These processes are particularly relevant in permafrost zones. We also simulate a higherresolution soil column and deeper soil, and include an additional thermal column at the base of the soil to represent bedrock. In addition, the snow scheme was improved to allow it to run with arbitrarily thin layers.Point-site simulations at Samoylov Island, Siberia, show that the model is now able to simulate soil temperatures and thaw depth much closer to the observations. The root mean square error for the near-surface soil temperatures reduces by approximately 30 %, and the active layer thickness is reduced from being over 1 m too deep to within 0.1 m of the observed active layer thickness. All of the model improvements contribute to improving the simulations, with organic matter having the single greatest impact. A new method is used to estimate active layer depth more accurately using the fraction of unfrozen water.Soil hydrology and snow are investigated further by holding the soil moisture fixed and adjusting the parameters to make the soil moisture and snow density match better with observations. The root mean square error in near-surface soil temperatures is reduced by a further 20 % as a result.

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“…There exist a variety of approaches for how such small-scale variability of different factors can be included in modelling (e.g. Fiddes et al, 2015;Kurylyk et al, 2016;Westermann et al, 2015;Zhang et al, 2012). As exemplified by Gisnås et al (2014) for mountain permafrost environments in Norway, redistribution of snow due to wind drift could be a governing factor for the ground thermal regime also in palsa mires, especially since palsas and peat plateaus are elevated landscape elements which feature lower snow depths than the surrounding mire area (Seppälä, 1982).…”

Section: Implications For Permafrost Modelling and Mappingmentioning

confidence: 99%

“…However, it is unclear whether the areal loss has been accompanied by systematic elevation changes of the surface due to melting of excess ground ice in the palsas and peat plateaus, followed by the drainage of the meltwater. One-dimensional model approaches for ground subsidence and thermokarst pond formation (Lee et al, 2014;Westermann et al, 2015) are a first step towards physically based modelling of thaw processes in ice-rich permafrost ground, but they must be included in a model framework that facilitates representing small-scale redistribution of heat, water and snow. Furthermore, fully coupled 3-D models have been demonstrated for larger thermokarst lakes (Kessler et al, 2012), and similar concepts may also be applicable to model palsa and peat plateau dynamics.…”

Section: Implications For Permafrost Modelling and Mappingmentioning

confidence: 99%

Strong degradation of palsas and peat plateaus in northern Norway during the last 60 years

et al. 2017

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Abstract. Palsas and peat plateaus are permafrost landforms occurring in subarctic mires which constitute sensitive ecosystems with strong significance for vegetation, wildlife, hydrology and carbon cycle. Firstly, we have systematically mapped the occurrence of palsas and peat plateaus in the northernmost county of Norway (Finnmark, ∼ 50 000 km 2 ) by manual interpretation of aerial images from 2005 to 2014 at a spatial resolution of 250 m. At this resolution, mires and wetlands with palsas or peat plateaus occur in about 850 km 2 of Finnmark, with the actual palsas and peat plateaus underlain by permafrost covering a surface area of approximately 110 km 2 . Secondly, we have quantified the lateral changes of the extent of palsas and peat plateaus for four study areas located along a NW-SE transect through Finnmark by utilizing repeat aerial imagery from the 1950s to the 2010s. The results of the lateral changes reveal a total decrease of 33-71 % in the areal extent of palsas and peat plateaus during the study period, with the largest lateral change rates observed in the last decade. However, the results indicate that degradation of palsas and peat plateaus in northern Norway has been a consistent process during the second half of the 20th century and possibly even earlier. Significant rates of areal change are observed in all investigated time periods since the 1950s, and thermokarst landforms observed on aerial images from the 1950s suggest that lateral degradation was already an ongoing process at this time. The results of this study show that lateral erosion of palsas and peat plateaus is an important pathway for permafrost degradation in the sporadic permafrost zone in northern Scandinavia. While the environmental factors governing the rate of erosion are not yet fully understood, we note a moderate increase in air temperature, precipitation and snow depth during the last few decades in the region.

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Future permafrost conditions along environmental gradients in Zackenberg, Greenland

Cited by 48 publications

References 76 publications

Spatio‐temporal dynamics of macroinvertebrate communities in northeast Greenlandic snowmelt streams

Spatio‐temporal dynamics of macroinvertebrate communities in northeast Greenlandic snowmelt streams

An improved representation of physical permafrost dynamics in the JULES land-surface model

Strong degradation of palsas and peat plateaus in northern Norway during the last 60 years

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