Permafrost Thickness Research Articles

A 12.5‐kyr history of vegetation dynamics and mire development with evidence of Younger Dryas larch presence in the Verkhoyansk Mountains, East Siberia, Russia

Werner, K., Tarasov, P. E., Andreev, A. A., Müller, S., Kienast, F., Zech, M., Zech, W. & Diekmann, B. 2009: A 12.5‐kyr history of vegetation dynamics and mire development with evidence of Younger Dryas larch presence in the Verkhoyansk Mountains, East Siberia, Russia. Boreas, 10.1111/j.1502‐3885.2009.00116.x. ISSN 0300‐9483.A 415 cm thick permafrost peat section from the Verkhoyansk Mountains was radiocarbon‐dated and studied using palaeobotanical and sedimentological approaches. Accumulation of organic‐rich sediment commenced in a former oxbow lake, detached from a Dyanushka River meander during the Younger Dryas stadial, at ∼12.5 kyr BP. Pollen data indicate that larch trees, shrub alder and dwarf birch were abundant in the vegetation at that time. Local presence of larch during the Younger Dryas is documented by well‐preserved and radiocarbon‐dated needles and cones. The early Holocene pollen assemblages reveal high percentages of Artemisia pollen, suggesting the presence of steppe‐like communities around the site, possibly in response to a relatively warm and dry climate ∼11.4–11.2 kyr BP. Both pollen and plant macrofossil data demonstrate that larch woods were common in the river valley. Remains of charcoal and pollen of Epilobium indicate fire events and mark a hiatus ∼11.0–8.7 kyr BP. Changes in peat properties, C31/C27 alkane ratios and radiocarbon dates suggest that two other hiatuses occurred ∼8.2–6.9 and ∼6.7–0.6 kyr BP. Prior to 0.6 kyr BP, a major fire destroyed the mire surface. The upper 60 cm of the studied section is composed of aeolian sands modified in the uppermost part by the modern soil formation. For the first time, local growth of larch during the Younger Dryas has been verified in the western foreland of the Verkhoyansk Mountains (∼170 km south of the Arctic Circle), thus increasing our understanding of the quick reforestation of northern Eurasia by the early Holocene.

Assessing the permafrost temperature and thickness conditions favorable for the occurrence of gas hydrate in the Qinghai–Tibet Plateau

Permafrost accounts for about 52% of the total area of the Qinghai–Tibet Plateau, and the permafrost area is about 140 × 10 4 km 2. The mean annual ground temperature of permafrost ranges from −0.1 to −5 °C, and lower than −5 °C at extreme high-mountains. Permafrost thickness ranges from 10 to 139.4 m by borehole data, and more than 200 m by geothermal gradients. The permafrost geothermal gradient ranges from 1.1 °C/100 m to 8.0 °C/100 m with an average of 2.9 °C/100 m, and the geothermal gradient of the soil beneath permafrost is about 2.8–8.5 °C/100 m with an average of 6.0 °C/100 m in the Qinghai–Tibet Plateau. For a minimum of permafrost geothermal gradients of 1.1 °C/100 m, the areas of the potential occurrence of methane hydrate (sI) is approximately estimated to be about 27.5% of the total area of permafrost regions in the Qinghai–Tibet Plateau. For an average of permafrost geothermal gradients of 2.9 °C/100 m, the areas of the potential occurrence of methane hydrate (sI) is approximately estimated about 14% of the total area of permafrost regions in the Qinghai–Tibet Plateau. For the sII hydrate, the areas of the potential occurrence of sII hydrate are more than that of sI methane hydrate.

PT-effects of Pleistocene glacial periods on permafrost, gas hydrate stability zones and reservoir of the Mittelplate oil field, northern Germany

During the past two million years low surface temperatures as well as episodically advancing ice sheets from Scandinavia acted on the subsurface pT-regime of northern Germany. Their likely effects on the petroleum system of Schleswig-Holstein were investigated. For the entire Quaternary mean annual ground temperature (MAGT) was reconstructed at a resolution of 1000 years by calibrating oxygen isotope records from ODP-site 659 to the climate of northern Germany of the past 120 kyr. The resulting MAGT trend served as input to an ice sheet model and a permafrost model along a 2D section crossing the petroleum bearing south-western part of Schleswig-Holstein. Here advances and retreats of the Scandinavian ice sheet during Saalian and Elsterian glaciation Stages were reconstructed. Maximum ice thicknesses of up to 1700 m and up to 20 periods of regional permafrost in northern Germany were reconstructed for the past 1.25 million years. Based on a basal heat flow of 50 mW/m 2 permafrost thicknesses exceeded 100 m during most of these periods, temporarily extending down to depths of more than 300 m. Favourable surface temperatures and long durations of cold periods provided favourable conditions for onshore gas hydrate stability zones at Mittelplate. Implementing these glacial dynamics into 2D basin modelling (PetroMod, IES, Aachen, Germany) of the Mittelplate oil field reveals five phases of gas hydrate stability at depths down to 750 m. The latest of these events occurred during the Weichselian about 20 kyr ago. The effect of the ice sheets on pore pressure in the subsurface strongly depends on the hydraulic boundary conditions at the ice base (e.g. frozen vs. temperate ice sheet base). Excess pore pressure in the reservoir of more than 10 MPa during ice overriding is possible and probable. The calculated temperature effect of the Pleistocene cooling on the Mittelplate reservoir is in the range of 3–7 °C. Even today temperature in the reservoir is still lowered by about 4 °C in comparison to pre-Pleistocene times. Despite the fact that a significant influence of glacial effects on petroleum generation can be ruled out at Mittelplate, we state that pT-effects in reservoirs related to glacial processes in formerly glaciated areas have been underestimated in the past.

Forecasting climate changes and the permafrost thickness for Central Yakutia into the year 2200

The method of harmonic analysis has been used to study the patterns of air and permafrost temperature changes across time for the city of Yakutsk spanning the previous 200 years of observation. The analysis revealed three harmonic functions which describe this temperature trend in a generalized form. These functions were used to develop the formula for calculating the temperature variation over time, and to predict the changes of climate and of the permafrost thickness in Central Yakutia into the year 2200.

Hydrogeochemistry of groundwaters in and below the base of thick permafrost at Lupin, Nunavut, Canada

Summary Shield fluids are commonly understood to evolve through water–rock interaction. However, fluids may also concentrate during ice formation. Very little is currently known about groundwater conditions beneath thick permafrost in crystalline environments. This paper evaluates three possible Shield fluid evolution pathways at a crystalline Shield location currently under 500+ meters of permafrost, including surfical cryogenic concentration of seawater, in situ cryogenic concentration and water–rock interaction. A primary goal of this study was to further scientific understanding of permafrost and its role in influencing deep flow system evolution, fluid movement and chemical evolution of waters in crystalline rocks. Precipitation, surface, permafrost and subpermafrost water samples were collected, as well as dissolved and free gas samples, fracture fillings and matrix fluid samples to characterize the site. Investigations of groundwater conditions beneath thick permafrost provides valuable information which can be applied to safety assessment of deep, underground nuclear waste repositories, effects of long-term mining in permafrost areas and understanding analogues to potential life-bearing zones on Mars. The study was conducted in the Lupin gold mine in Nunavut, Canada, located within the zone of continuous permafrost. Through-taliks beneath large lakes in the area provided potential hydraulic connections through the permafrost. Na–Cl and Na–Cl–SO4 type permafrost waters were contaminated by mining activities, affecting the chloride and nitrate concentrations. High nitrate concentrations (423–2630 mg L−1) were attributed to remnants of blasting. High sulfate concentrations in the permafrost (578–5000 mg L−1) were attributed to naturally occurring and mining enhanced sulfide oxidation. Mine dewatering created an artificial hydraulic gradient, resulting in methane hydrate dissociation at depth. Less contaminated basal waters had medium sulfate concentrations and were Ca–Na dominated, similar to deeper subpermafrost waters. Subpermafrost waters had a wide range of salinities (2.6–40 g L−1). It was unclear from this investigation what impact talik waters would have on deep groundwaters in undisturbed environments. In situ cryogenic concentration due to ice and methane hydrate formation may have concentrated the remaining fluids, however there was no evidence that infiltration of cryogenically concentrated seawater occurred since the last glacial maximum. Matrix waters were dilute and unable to affect groundwater salinity. Fracture infillings were scarce, but calcite fluid inclusion microthermometry indicated a large range in salinities, potentially an additional source of salinity to the system.

The thermal regime of permafrost and its susceptibility to degradation in upland terrain near Inuvik, N.W.T.

AbstractMean near‐surface ground temperatures in upland terrain near Inuvik range between −4°C and −1.2°C and the thickness of permafrost is about 90 m. The warm permafrost is due to the relatively deep snow cover that accumulates in the open‐canopy forest. Changes in surface conditions may lead to permafrost degradation in this environment, as is evident from elevated ground temperatures beneath disturbed surfaces in a gravel pit, in terrain burned by forest fire and where the snow depth has been increased by fencing. The values for mean annual ground temperature near Inuvik are lower end‐members of the distribution of ground temperatures in the boreal forests of northwest Canada. The range in the mean temperature of near‐surface permafrost throughout this 1200‐km wide belt (from 0°C to about −4°C) is comparable to the range over 100 km northwards from Inuvik across the treeline (from about −4°C to −8°C). Copyright © 2009 John Wiley & Sons, Ltd. and Her Majesty the Queen in right of Canada.

The environment and permafrost of the Mackenzie Delta area

AbstractThe Mackenzie Delta, prograding northwestwards into the Beaufort Sea, is North America's largest arctic delta. This Holocene feature is bounded by rolling uplands to the east and the Richardson Mountains to the west. Treeline traverses the region, separating the subarctic boreal forest in southern parts from low‐shrub tundra and sedge wetlands at the coast. The region is experiencing rapid climate change, and mean annual air temperature has increased by more than 2.5°C since 1970. The area was at the margin of the Wisconsinan ice sheet, so that in the uplands the mean annual ground temperature and glacial history control permafrost thickness, which varies from >700 m to <100 m. Ground temperatures in the delta are distinct from the uplands due to the thermal influence of numerous lakes and shifting channels. In the uplands, ground temperatures decrease northwards across treeline in association with a decrease in the thickness of snow cover. Ground temperatures have increased since 1970 in the uplands by approximately 1.5°C in association with rising annual mean air temperature. The increase has been less in the delta south of treeline due to the extensive thermal influence of water bodies on ground temperature. However, in the outer delta, the ground is currently more than 2.5°C warmer than in 1970. The impact of climate change on permafrost is also evident in the thickness of the active layer, which increased on average by 8 cm at 12 tundra sites on northern Richards Island from 1983–2008. Copyright © 2009 John Wiley & Sons, Ltd. and Her Majesty the Queen in right of Canada.

Novel sulfur‐oxidizing streamers thriving in perennial cold saline springs of the Canadian high Arctic

The perennial springs at Gypsum Hill (GH) and Colour Peak (CP), situated at nearly 80 degrees N on Axel Heiberg Island in the Canadian high Arctic, are one of the few known examples of cold springs in thick permafrost on Earth. The springs emanate from deep saline aquifers and discharge cold anoxic brines rich in both sulfide and sulfate. Grey-coloured microbial streamers form during the winter months in snow-covered regions of the GH spring run-off channels (-1.3 degrees C to 6.9 degrees C, approximately 7.5% NaCl, 0-20 p.p.m. dissolved sulfide, 1 p.p.m. dissolved oxygen) but disappear during the Arctic summer. Culture- and molecular-based analyses of the 16S rRNA gene (FISH, DGGE and clone libraries) indicated that the streamers were uniquely dominated by chemolithoautotrophic sulfur-oxidizing Thiomicrospira species. The streamers oxidized both sulfide and thiosulfate and fixed CO(2) under in situ conditions and a Thiomicrospira strain isolated from the streamers also actively oxidized sulfide and thiosulfate and fixed CO(2) under cold, saline conditions. Overall, the snow-covered spring channels appear to represent a unique polar saline microhabitat that protects and allows Thiomicrospira streamers to form and flourish via chemolithoautrophic, phototrophic-independent metabolism in a high Arctic winter environment characterized by air temperatures commonly below -40 degrees C and with an annual average air temperature of -15 degrees C. These results broaden our knowledge of the physical and chemical boundaries that define life on Earth and have astrobiological implications for the possibility of life existing under similar Martian conditions.

Mountain permafrost landscapes of Yakutia

An analysis is made of the spectrum of altitudinal zonality of mountain permafrost landscapes of Yakutia. The intervals of the values of characteristics of particular landscape altitudinal zones are provided, namely, the marks of their boundaries in accordance with a change in the latitude of the locality, the indices of freezing and thawing, mean yearly air temperatures, the pattern of occurrence, the thickness and temperature of permafrost, the thickness of the active layer as well as the accompanying permafrost-geological processes and phenomena.

About this title - Periglacial and Paraglacial Processes and Environments

Periglacial and paraglacial environments, located outside ice sheet margins but responding to similar climate forcings, are key to identifying climate change effects upon the Earth system. These environments are relicts of cold Earth processes and so are most sensitive to global warming. Changes in the distribution and thickness of permafrost in continental interiors have implications for ecosystem and landscape stability. Periglacial Alpine environments are experiencing increased rockfall and mass movement, leading to rock glacier instability and sediment release to downstream rivers. In turn, these landscape effects impact on natural hazards and human activities in these sensitive and geologically transient environments. Papers in this volume explore some of these interrelated issues in field studies from Europe, North America and Asia. The volume will be of interest to geomorphologists, modellers, environmental managers, planners and engineers working on landscape, climate and environmental change in periglacial and paraglacial areas.

Rapid degradation of ground ice in a ventilated talus slope: Flüela Pass, Swiss Alps

AbstractThe degradation of ground ice in talus deposits, which are important forms of debris storage in mountain environments, can cause mass movements, subsidence or instability of mountain infrastructure. Two 20 m deep boreholes instrumented with thermistors and located in a talus slope at 2400 m asl above a lake at Flüela Pass in the eastern Swiss Alps allow the analysis of the evolution of ground temperature and permafrost thickness between 2003 and 2008. The occurrence of intra‐talus ventilation can be discerned due to thermal anomalies within a layer of coarse blocks with large voids at around 15 m depth near the base of the slope and at 10 m depth mid‐slope. Intra‐talus ventilation is particularly effective in winter when subzero air temperatures coincide with snow depths less than 50 cm and reverses to a gravity discharge of intra‐talus air when air temperatures become positive. Despite the lack of annual variability in active layer depth, rapid permafrost degradation and thinning of ground ice (from 7 m thickness to 3.5 m in 4 years) is currently occurring. It is attributed to latent heat transfer from the moving air stream, caused by the flux of vapour from the relatively warm lake water table at 20 m depth and its condensation at the base of the permafrost body. Copyright © 2009 John Wiley & Sons, Ltd.

Heterotrophic and Autotrophic Microbial Populations in Cold Perennial Springs of the High Arctic

The saline springs of Gypsum Hill in the Canadian high Arctic are a rare example of cold springs originating from deep groundwater and rising to the surface through thick permafrost. The heterotrophic bacteria and autotrophic sulfur-oxidizing bacteria (up to 40% of the total microbial community) isolated from the spring waters and sediments were classified into four phyla (Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria) based on 16S rRNA gene analysis; heterotrophic isolates were primarily psychrotolerant, salt-tolerant, facultative anaerobes. Some of the isolates contained genes for thiosulfate oxidation (soxB) and anoxygenic photosynthesis (pufM), possibly enabling the strains to better compete in these sulfur-rich environments subject to long periods of illumination in the Arctic summer. Although leucine uptake by the spring water microbial community was low, CO(2) uptake was relatively high under dark incubation, reinforcing the idea that primary production by chemoautotrophs is an important process in the springs. The small amounts of hydrocarbons in gases exsolving from the springs (0.38 to 0.51% CH(4)) were compositionally and isotopically consistent with microbial methanogenesis and possible methanotrophy. Anaerobic heterotrophic sulfur oxidation and aerobic autotrophic sulfur oxidation activities were demonstrated in sediment slurries. Overall, our results describe an active microbial community capable of sustainability in an extreme environment that experiences prolonged periods of continuous light or darkness, low temperatures, and moderate salinity, where life seems to rely on chemolithoautotrophy.

Mountain permafrost on active volcanoes: field data and statistical mapping, Klyuchevskaya volcano group, Kamchatka, Russia

AbstractPermafrost is widespread in mountainous volcanic areas of the Kamchatka Peninsula. In this paper, we describe geocryological conditions (active layer depths, permafrost temperatures, ground thermal properties and cryostratigraphy) in the Klyuchevskaya volcano group and estimate the spatial distribution of permafrost using a simple statistical model. Measured mean annual ground temperatures (MAGTs) vary from near 0°C around 950 m a.s.l. to −7°C at 2500 m a.s.l. and permafrost is predicted to occur at elevations >∼700 m a.s.l. Heat transfer modelling indicates that the maximum permafrost thickness is about 1000 m for the highest summits (∼5000 m a.s.l.). Copyright © 2008 John Wiley & Sons, Ltd.

Challenges for Coring Deep Permafrost on Earth and Mars

A scientific drilling expedition to the High Lake region of Nunavut, Canada, was recently completed with the goals of collecting samples and delineating gradients in salinity, gas composition, pH, pe, and microbial abundance in a 400 m thick permafrost zone and accessing the underlying pristine subpermafrost brine. With a triple-barrel wireline tool and the use of stringent quality assurance and quality control (QA/QC) protocols, 200 m of frozen, Archean, mafic volcanic rock was collected from the lower boundary that separates the permafrost layer and subpermafrost saline water. Hot water was used to remove cuttings and prevent the drill rods from freezing in place. No cryopegs were detected during penetration through the permafrost. Coring stopped at the 535 m depth, and the drill water was bailed from the hole while saline water replaced it. Within 24 hours, the borehole iced closed at 125 m depth due to vapor condensation from atmospheric moisture and, initially, warm water leaking through the casing, which blocked further access. Preliminary data suggest that the recovered cores contain viable anaerobic microorganisms that are not contaminants even though isotopic analyses of the saline borehole water suggests that it is a residue of the drilling brine used to remove the ice from the upper, older portion of the borehole. Any proposed coring mission to Mars that seeks to access subpermafrost brine will not only require borehole stability but also a means by which to generate substantial heating along the borehole string to prevent closure of the borehole from condensation of water vapor generated by drilling.

Assessment of frozen-ground conditions for engineering geology along the Qinghai–Tibet highway and railway, China

The Qinghai–Tibet Highway and Railway (the Corridor) across the Qinghai–Tibet Plateau traverses 670 km of permafrost and seasonally frozen-ground in the interior of the Plateau, which is sensitive to climatic and anthropogenic environmental changes. The frozen-ground conditions for engineering geology along the Corridor is complicated by the variability in the near-surface lithology, and the mosaic presence of warm permafrost and talik in a periglacial environment. Differential settlement is the major frost-effect problem encountered over permafrost areas. The traditional classification of frozen ground based on the areal distribution of permafrost is too generalized for engineering purposes and a more refined classification is necessary for engineering design and construction. A proposed classification of 51 zones, sub-zones, and sections of frozen ground has been widely adopted for the design and construction of foundations in the portion of the Corridor studied. The mean annual ground temperature (MAGT), near-surface soil types and moisture content, and active faults and topography are most commonly the primary controlling factors in this classification. However, other factors, such as local microreliefs, drainage conditions, and snow and vegetation covers also exert important influences on the features of frozen ground. About 60% of the total length of the Corridor studied possesses reasonably good frozen-ground conditions, which do not need special mitigative measures for frost hazards. However, other sections, such as warm and ice-rich or -saturated permafrost, particularly in the sections in wetlands, ground improvement measures such as elevated land bridges and passive or proactive cooling techniques need to be applied to ensure the long-term stability of thermally unstable, thick permafrost subsoils, and/or refill with non-frost-susceptible soils. Due to the long-history of the construction and management of the Corridor by various government departments, adverse impacts of construction and operation on the permafrost environment have been resulted. It is recommended that an integrated, executable plan for the routing of major construction projects within this transportation corridor be established and long-term monitoring networks installed for evaluating and mitigating the impact from anthropogenic and climatic changes in frozen-ground conditions.

Mapping vertical profile of discontinuous permafrost with ground penetrating radar at Nalaikh depression, Mongolia

Ground-penetrating radar (GPR) has become an important geophysical tool which can provide a wealth of interpretive information about the vertical profile of discontinuous permafrost. A GPR investigation was conducted in October 2006 at the Nalaikh site at the southern boundary of the Siberian discontinuous permafrost region in Mongolia. GPR data were collected along four 100-m-long profiles to identify the location of the permafrost body, which included an in situ drilling borehole and analysis of temperature observations and soil water content measurements from boreholes. The GPR interpretation results indicated that the thickness of discontinuous permafrost at the study site was only 1.9–3.0 m and the permafrost is vulnerable to climate change. The soil temperature and soil water content data demonstrate the precision of GPR image interpretation. This case demonstrated that GPR is well suited for mapping the internal structure of discontinuous permafrost with relatively low soil water content.

Influencing factors of water resources in the source region of the Yellow River

Taking the source region of the Yellow River as a study area and based on the data from Madoi Meteorological Station and Huangheyan Hydrological Station covering the period 1955–2005, this paper analyses the changing trends of surface water resources, climate and frozen ground and reveals their causes. Results show that there exist frequent fluctuations from high to low water flow in the 51-year period. In general, the discharge has shown a declining trend in the 51 years especially since the 1990s. The annual distribution shows one peak which, year on year is getting smaller. (1) Precipitation has a significant and sustained influence on discharge. (2) A sharp rise of temperature resulted in the increase of evaporation and the decrease of discharge, which has a greater effect than on ice-snow melting. (3) Frozen ground tends to be degraded markedly. There is a significant positive correlation between the permafrost thickness and the discharge. (4) Evaporation rates are significantly increasing, leading to the decrease of discharge. 70% of the discharge reduction resulted from climate change, and the remaining 30% may have been caused by human activities.

Characterization of the prokaryotic diversity in cold saline perennial springs of the Canadian high Arctic.

The springs at Gypsum Hill and Colour Peak on Axel Heiberg Island in the Canadian Arctic originate from deep salt aquifers and are among the few known examples of cold springs in thick permafrost on Earth. The springs discharge cold anoxic brines (7.5 to 15.8% salts), with a mean oxidoreduction potential of -325 mV, and contain high concentrations of sulfate and sulfide. We surveyed the microbial diversity in the sediments of seven springs by denaturing gradient gel electrophoresis (DGGE) and analyzing clone libraries of 16S rRNA genes amplified with Bacteria and Archaea-specific primers. Dendrogram analysis of the DGGE banding patterns divided the springs into two clusters based on their geographic origin. Bacterial 16S rRNA clone sequences from the Gypsum Hill library (spring GH-4) were classified into seven phyla (Actinobacteria, Bacteroidetes, Firmicutes, Gemmatimonadetes, Proteobacteria, Spirochaetes, and Verrucomicrobia); Deltaproteobacteria and Gammaproteobacteria sequences represented half of the clone library. Sequences related to Proteobacteria (82%), Firmicutes (9%), and Bacteroidetes (6%) constituted 97% of the bacterial clone library from Colour Peak (spring CP-1). Most GH-4 archaeal clone sequences (79%) were related to the Crenarchaeota while half of the CP-1 sequences were related to orders Halobacteriales and Methanosarcinales of the Euryarchaeota. Sequences related to the sulfur-oxidizing bacterium Thiomicrospira psychrophila dominated both the GH-4 (19%) and CP-1 (45%) bacterial libraries, and 56 to 76% of the bacterial sequences were from potential sulfur-metabolizing bacteria. These results suggest that the utilization and cycling of sulfur compounds may play a major role in the energy production and maintenance of microbial communities in these unique, cold environments.

Impacts of permafrost changes on alpine ecosystem in Qinghai-Tibet Plateau

Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem. The vegetation coverage, grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau. The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer, permafrost thickness and mean annual ground temperature (MAGTs). Based on the statistics model of GPTR for MAGTs and annual air temperatures, an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems. Under the climate change and human engineering activities, the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun Mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper. The results showed that the permafrost changes have a different influence on different alpine ecosystems. With the increase in the thickness of active layer, the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction, the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease, and the surface soil materials become coarse and gravelly. The alpine cold steppe ecosystem, however, seems to have a relatively weak relation to the permafrost environment. Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98% and alpine cold swamp decreased by 28.11% under the permafrost environment degradation during recent 15 years. In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions, among them the alpine cold meadow and swamp ecosystem located in the low mountain and plateau area will have a relatively serious degradation. Furthermore, from the angles of grassland coverage and biological production the variation characteristics of high-cold ecosystems in different representative regions and different geomorphologic units under different climatic conditions were quantitatively assessed. In the future, adopting effective measures to protect permafrost is of vital importance to maintaining the stability of permafrost engineering and alpine cold ecosystems in the plateau.

Comment on “A projection of severe near‐surface permafrost degradation during the 21st century” by David M. Lawrence and Andrew G. Slater

Comment on “A projection of severe near‐surface permafrost degradation during the 21st century” by David M. Lawrence and Andrew G. Slater