Search

The Arctic is experiencing pronounced climatic and environmental changes. These changes pose a risk to infrastructure, impacting the accessibility and development of remote locations and ad...

Increasing atmospheric temperatures over the last 30 years has prompted land cover change in sensitive Arctic environments and exacerbated change in large urban-industrial centers on permaf...

The city of Norilsk represents an unprecedented case of massive construction in the permafrost regions of the Arctic. Norilsk’s urban expansion can be attributed to the development of engineering practices that maintained the thermal stability of permafrost. However, complex interactions between the urban landscape and permafrost have resulted in permafrost warming and degradation. Negative cryogenic processes started to manifest themselves 10–15 years after the initial development and have intensified with time. Problems were further exacerbated by the poor quality of construction, improper operation of the city infrastructure, socio-economic transitions, and unanticipated climatic changes. The warming and degradation of permafrost have contributed to a widespread deformation of structures in Norilsk. In this paper, we discuss the role of permafrost in the urban development of Norilsk, specific human- and climate-induced geotechnical problems related to permafrost, and innovative economically via...

Ice cellars are a natural form of refrigeration constructed within permafrost. They are traditionally employed by indigenous Arctic peoples to store harvested wildlife. Recent reports from Alaska i...

Climate warming is occurring at an unprecedented rate in the Arctic due to regional amplification, potentially accelerating land cover change. Measuring and monitoring land cover change utilizing optical remote sensing in the Arctic has been challenging due to persistent cloud and snow cover issues and the spectrally similar land cover types. Google Earth Engine (GEE) represents a powerful tool to efficiently investigate these changes using a large repository of available optical imagery. This work examines land cover change in the Lower Yenisei River region of arctic central Siberia and exemplifies the application of GEE using the random forest classification algorithm for Landsat dense stacks spanning the 32-year period from 1985 to 2017, referencing 1641 images in total. The semiautomated methodology presented here classifies the study area on a per-pixel basis utilizing the complete Landsat record available for the region by only drawing from minimally cloud- and snow-affected pixels. Climatic changes observed within the study area’s natural environments show a statistically significant steady greening (~21,000 km2 transition from tundra to taiga) and a slight decrease (~700 km2) in the abundance of large lakes, indicative of substantial permafrost degradation. The results of this work provide an effective semiautomated classification strategy for remote sensing in permafrost regions and map products that can be applied to future regional environmental modeling of the Lower Yenisei River region.

Russian regions containing permafrost play an important role in the Russian economy, containing vast reserves of natural resources and hosting large-scale infrastructure to facilitate these resources' exploitation. Rapidly changing climatic conditions are a major concern for the future economic development of these regions. This study examines the extent to which infrastructure and housing are affected by permafrost in Russia and estimates the associated value of these assets. An ensemble of climate projections is used as a forcing to a permafrost-geotechnical model, in order to estimate the cost of buildings and infrastructure affected by permafrost degradation by mid-21st century under RCP 8.5 scenario. The total value of fixed assets on permafrost was estimated at 248.6 bln USD. Projected climatic changes will affect 20% of structures and 19% of infrastructure assets, costing 16.7 bln USD and 67.7 bln USD respectively to mitigate. The total cost of residential real estate on permafrost was estimated at 52.6 bln USD, with 54% buildings affected by significant permafrost degradation by the mid-21st century. The paper discusses the variability in climate-change projections and the ability of Russia's administrative regions containing permafrost to cope with projected climate-change impacts. The study can be used in land use planning and to promote the development of adaptation and mitigation strategies for addressing the climate-change impacts of permafrost degradation on infrastructure and housing.

The active layer plays an important role in the functioning of environmental ecosystems and affects many human activities in the polar regions. Regional assessments and predictions of this parameter are critical for many physical and social applications. Large heterogeneity in near-surface permafrost characteristics, including the active layer, even over small distances, creates serious constraints to their evaluation across large geographic extents. Discrepancies between modeled climatic fields add to the uncertainties associated with predicting active-layer thickness (ALT) at regional scales. This study uses a stochastic approach, in combination with an equilibrium permafrost model, to map the geographic distribution of ALT and near-surface permafrost temperature on the North Slope of Alaska. GIS techniques are used to determine the spatial variabilityof ecosystem factors controlling the ground thermal regime within each grid cell of the permafrost model. To incorporate the uncertainty associated with t...

Arctic settlements built on permafrostface rather unique set of geotechnical challenges. On urbanized areas, technogenic transformation of natural landscapes due toconstruction of various types of infrastructure leads to changes in heat exchange in permafrost-atmosphere system. The spatial distribution and intensity of dangerous cryogenic processes in urbanized areas is substantially different from natural background settings found prior to construction. Climate change, especially pronounced in the Arctic, exacerbated these changes. Combination of technogenic pressure and climate change resulted in potentially hazardous situation in respect to operational safety of the buildings and structures built on permafrost. This paper is focused on geotechnical safety issues faced by the Arctic urban centers built on permafrost. Common types of technogenic impacts characteristic for urban settlements wereevaluated based on field observations and modeling techniques. The basic principles of development of deformations are discussed in respect to changing permafrost conditions and operational mode of the structures built on permafrost.

A significant portion of the Tibetan Plateau is underlain by permafrost, and is highly sensitive to climate change. Observational data from recent Chinese investigations on permafrost degradation and its environmental effects in the Tibetan region indicate that a large portion of the Tibetan Plateau has experienced significant warming since the mid-1950s. The air temperature increase is most significant in the central, eastern, and northwestern parts of the Plateau. The warming trend in the cold season was greater than that in the warm season. The duration of seasonal ground freezing has shortened due to the air temperature increase in winter. Numerical simulations indicate that air temperature on the Plateau will continue to increase in the 21st century. Significant warming has resulted in extensive degradation of permafrost. Over the last 30 years, a 25 m increase in the lower altitudinal occurrences of permafrost has taken place in the north. In the south the increase is 50–80 m over the past 20 years. Active-layer thickness and mean annual ground temperature have increased by 0.15–0.50 m during 1996–2001 and by 0.1–0.5 °C during the last 30 years on the Tibetan Plateau, respectively. Widespread permafrost degradation has already caused environmental deterioration. Extensive desertification processes are apparent in the eastern and western portions of the Tibetan Plateau, with the area occupied by desert increasing annually by about 1.8%. With rapid retreat and thinning of permafrost, large carbon pools sequestered in permafrost could be released to increase net sources of atmospheric carbon, creating a positive feedback and accelerated warming. Damage to human infrastructure is also caused by frost heave, thaw settlement, and thaw slumping in the permafrost-affected region. The impact of permafrost degradation on energy and water exchange processes between the ground and atmosphere require further examination. Large-scale intensive monitoring networks, remote sensing investigations, and models for frozen soil are needed to clarify regional details of climate change, permafrost degradation, and their environmental effects.

Thawing permafrost and the resulting microbial decomposition of previously frozen organic carbon (C) is one of the most significant potential feedbacks from terrestrial ecosystems to the atmosphere in a changing climate. In this article we present an overview of the global permafrost C pool and of the processes that might transfer this C into the atmosphere, as well as the associated ecosystem changes that occur with thawing. We show that accounting for C stored deep in the permafrost more than doubles previous high-latitude inventory estimates, with this new estimate equivalent to twice the atmospheric C pool. The thawing of permafrost with warming occurs both gradually and catastrophically, exposing organic C to microbial decomposition. Other aspects of ecosystem dynamics can be altered by climate change along with thawing permafrost, such as growing season length, plant growth rates and species composition, and ecosystem energy exchange. However, these processes do not appear to be able to com...

Although maps of active-layer thickness have useful roles in geocryology, polar ecology, and hydrology, a lack of geographically distributed data at appropriate scales has prevented their widespread implementation. The n-factor (ratio of temperature at the soil surface to that in the air) has considerable potential as a tool for mapping active-layer thickness and other geocryological parameters by providing refinements to relatively simple analytic solutions for the depth of thaw. Although temperature data from the soil surface under representative land-cover units have rarely been collected historically, recent advancements in data-logger technology allow the variability of soil-surface temperature regimes to be assessed inexpensively over small temporal and spatial intervals. Temperature data collected in the air at 2 m height and at the soil surface within 10 representative land-cover units in the Kuparuk River region of north-central Alaska were used to compute seasonal n-factor values for specific ve...

The n-factor, or ratio of the seasonal degree-day sum at the soil surface to that in the air at standard screen height, has been used for more than 40 yr in engineering studies to parameterize the ...

The initial response of permafrost to global warming could be an increase in active-layer thickness. Given that such changes could have severe consequences for human infrastructure and ecosystem stability, it is important to obtain information about spatial variations of the active layer corresponding to current climatic conditions, and to determine the magnitude of possible near-surface permafrost degradation associated with climatic change. Simple analytical solutions for frost and thaw penetration depth have long been available, but were used primarily for practical applications at point locations in cold-region engineering. One of these methods, developed at Moscow State University by Kudryavtsev and co-workers, was used to develop a spatially distributed analytic model that estimates the maximum annual depth of thaw. Kudryavtsev’s procedures account for the effects of snow cover, vegetation, soil moisture, thermal properties, and regional climate, and provide estimates of surface temperature and active-layer thickness. GIS techniques were used to incorporate climate records, digital cartographic products, and field data into a spatially distributed estimate of active-layer thickness. Procedures were applied over a rectangular 22 300 km2 area in north-central Alaska containing complex patterns of topography, vegetation, and soils. Validation procedures indicate that the Kudrayavtsev solution, adapted for spatial applications, yields accuracy and spatial resolution comparable to an existing semi-empirical method. The simplicity and low data requirements of the Kudryavtsev solution make it readily adaptable to different geographic scales and areas. The method has potential applications in climate-change studies.

Studies and models of trace-gas flux in the Arctic consider temperature and moisture to be the dominant controls over land–atmosphere exchange1,2, with little attention having been paid to the effects of different substrates. Likewise, current Arctic vegetation maps for models of vegetation change recognize one or two tundra types3,4 and do not portray the extensive regions with different soils within the Arctic. Here we show that rapid changes to ecosystem processes (such as photosynthesis and respiration) that are related to changes in climate and land usage will be superimposed upon and modulated by differences in substrate pH. A sharp soil pH boundary along the northern front of the Arctic Foothills in Alaska separates non-acidic (pH > 6.5) ecosystems to the north from predominantly acidic (pH < 5.5) ecosystems to the south. Moist non-acidic tundra has greater heat flux, deeper summer thaw (active layer), is less of a carbon sink, and is a smaller source of methane than moist acidic tundra.

This chapter examines effects of climate change on human infrastructure in permafrost regions of Siberia. The presence and dynamic nature of ice-rich permafrost constitute a distinctive engineering environment. Many engineering problems in Siberia are associated with (1) changes in the temperature of the upper permafrost, (2) increased depth of seasonal thaw penetration, and (3) progressive thawing and disappearance of permafrost. These changes can lead to loss of soil bearing strength, increased soil permeability, and increased potential for development of such cryogenic processes as differential thaw settlement and heave, and development of thermokarst terrain. Each of these phenomena has the capacity for severe negative consequences on human infrastructure in the high latitudes. Results to date indicate that major permafrost-related impacts have already been detected in many Siberian regions, including changes in the temperature and distribution of permafrost, thickening of the seasonally thawed layer (the active layer), and changes in the distribution and quantity of ice in the ground. A quantitative geographic assessment of the ability of frozen ground to support engineering structures under rapidly changing climatic conditions in a variety of settings is provided in this chapter. Results show substantial decreases of permafrost bearing capacity over the last 40 years in some regions of Northern Siberia. Although a substantial proportion of reported deformations of structures and buildings on permafrost can be attributed to climatic warming, other technogenic factors have to be considered. The socioeconomic crisis resulted in reduced infrastructure monitoring and maintenance in many cities on permafrost during the early 1990s which have greatly contributed to the decrease in infrastructure stability.

[1] A continuous time series of annual soil thaw records, extending from 1994 to 2009, is available for comparison with the records of thaw obtained from the Biocomplexity Experiment (BE) for the period 2006–2009. Discontinuous records of thaw at Barrow from wet tundra sites date back to the 1960s. Comparisons between the longer records with the BE observations reveal strong similarities. Records of permafrost temperature, reflecting changes in the annual surface energy exchange, are available from the 1950s for comparison with results from measurement programs begun in 2002. The long-term systematic geocryological investigations at Barrow indicate an increase in permafrost temperature, especially during the last several years. The increase in near-surface permafrost temperature is most pronounced in winter. Marked trends are not apparent in the active-layer record, although subsidence measurements on the North Slope indicate that penetration into the ice-rich layer at the top of permafrost has occurred over the past decade. Active-layer thickness values from the 1960s are generally higher than those from the 1990s, and are very similar to those of the 2000s. Analysis of spatial active-layer observations at representative locations demonstrates significant variations in active-layer thickness between different landscape types, reflecting the influence of vegetation, substrate, microtopography, and, especially, soil moisture. Landscape-specific differences exist in the response of active-layer thickness to climatic forcing. These differences are attributable to the existence of localized controls related to combinations of surface and subsurface characteristics. The geocryological records at Barrow illustrate the importance and effectiveness of sustained, well organized monitoring efforts to document long-term trends.

[1] Several model-based assessments predict a discernible increase in the depth of seasonal thawing and circumpolar-scale warming of permafrost by the mid-21st century. Quantitative estimates of the environmental and socioeconomic impacts of changing climate in northern regions require robust projection of changes in permafrost, which in turn depend on the availability of appropriate models and forcing data. We examined four high-resolution, hemispheric-scale gridded sets of monthly temperature and precipitation constructed using different interpolation routines and reanalysis of data from a large number of weather stations. At many of 455 Russian weather stations, the four data sets depart from empirical mean annual air temperatures averaged over the 15-year period by 1–2°C and in cumulative daily positive temperature sums (degree days of thawing) by more than 200°C days. A permafrost model, forced with the gridded climatic data sets, was used to calculate the large-scale characteristics of permafrost in northern Eurasia. We analyzed zonal-mean air and ground temperatures, depth of seasonal thawing, and area occupied by near-surface permafrost in Eurasia north of 45°N. The 0.5–1.0 °C difference in zonal-mean air temperature between the data sets translates into a range of uncertainty of 10–20% in estimates of near-surface permafrost area, which is comparable to the extent of changes projected for the following several decades. We conclude that more observations and theoretical studies are needed to improve characterization of baseline climatic conditions and to narrow the range of uncertainties in model-based permafrost projections.

Role of changing climatic conditions on permafrost degradation and hydrology was investigated in the transition zone between the tundra and forest ecotones at the boundary of continuous and discontinuous permafrost of the lower Yenisei River. Three watersheds of various sizes were chosen to represent the characteristics of the regional landscape conditions. Samples of river flow, precipitation, snow cover, and permafrost ground ice were collected over the watersheds to determine isotopic composition of potential sources of water in a river flow over a two year period. Increases in air temperature over the last forty years have resulted in permafrost degradation and a decrease in the seasonal frost which is evident from soil temperature measurements, permafrost and active-layer monitoring, and analysis of satellite imagery. The lowering of the permafrost table has led to an increased storage capacity of permafrost affected soils and a higher contribution of ground water to river discharge during winter months. A progressive decrease in the thickness of the layer of seasonal freezing allows more water storage and pathways for water during the winter low period making winter discharge dependent on the timing and amount of late summer precipitation. There is a substantial seasonal variability of stable isotopic composition of river flow. Spring flooding corresponds to the isotopic composition of snow cover prior to the snowmelt. Isotopic composition of river flow during the summer period follows the variability of precipitation in smaller creeks, while the water flow of larger watersheds is influenced by the secondary evaporation of water temporarily stored in thermokarst lakes and bogs. Late summer precipitation determines the isotopic composition of texture ice within the active layer in tundra landscapes and the seasonal freezing layer in forested landscapes as well as the composition of the water flow during winter months.

The threat to man-made structures across regions in the far north can be monitored. The thawing and disappearance of permafrost has accelerated in recent decades1, damaging buildings and infrastructure and causing public concern2. Here we offer a geographic overview of the hazard potential associated with thawing permafrost in the Northern Hemisphere which indicates that vulnerability to subsidence is widespread. Much of the existing infrastructure erected in northern regions is located in areas of high hazard potential and could be affected by thaw subsidence under conditions of global warming.

Numerous studies indicate that the northern high latitudes are experiencing an unprecedented rate of environmental change, including an increase in air temperatures (e.g. Serreze and Francis 2006), reduction of snow cover (e.g. Brown and Robinson 2011), ecosystem transformations and land cover changes (e.g. Callaghan et al 2011). Many of the potential environmental impacts of global warming in the high latitudes are associated with frozen ground, which occupies about 55% of the unglaciated land area in the northern hemisphere and consists of both permafrost and seasonally frozen ground. Frozen soils have a tremendous impact on hydrologic, climatic and biologic systems. Periodic freezing and thawing promote changes in soil structure, affect the surface and subsurface water cycle, and regulate the availability of nutrients in the soil for plants and biota that depend upon them. Freezing and thawing cycles can affect the decomposition of organic substances in the soil and greenhouse gas exchange between the atmosphere and land surface. Significant efforts have been devoted to permafrost-related studies, including the establishment of standardized observations (e.g. Romanovsky et al 2010, Shiklomanov et al 2008), modeling (e.g. Riseborough et al 2008), and climate-related feedback processes (e.g. Schuur et al 2008). Despite its vast extent and importance, seasonally frozen ground has received much less attention. One of the major obstacles in assessing changes in seasonally frozen ground is the lack of long-term data. In general, observations on soil temperature and freeze propagation are available for a limited area and involve a relatively short time period, precluding assessment of long-term, climate-driven change. A few known exceptions include shallow soil temperature and freeze/thaw depth observations conducted as part of the standard hydrometeorological monitoring system in China (e.g. Zhao et al 2004) and the Soviet Union/Russia (e.g. Gilichinsky et al 2000). In their recent paper entitled 'An observational 71-year history of seasonally frozen ground changes in Eurasian high latitudes', Frauenfeld and Zhang (2011) provided detailed analysis of soil temperature data to assess 1930–2000 trends in seasonal freezing depth. The data were obtained from 387 Soviet non-permafrost meteorological stations. The authors performed systematic, quality-controlled, integrative analysis over the entire former Soviet Union domain. The long-term changes in depth of seasonal freezing were discussed in relation to such forcing variables as air temperature, degree days of freezing/thawing, snow depth and summer precipitation as well as modes of the North Atlantic Oscillation. The spatially average approach adopted for the study provides a generalized continental-scale trend. The study greatly improves, expands and extends previous 1956–90 analysis of the ground thermal regime over the Eurasian high latitudes (Frauenfeld et al 2004). Although the work of Frauenfeld and Zhang (2011) is the most comprehensive assessment of the continental-scale long-term trends in seasonal freezing available to date, more detailed analysis is needed to determine the effect of climate change on seasonally frozen ground. It should be noted that, in addition to the variables considered for analysis, other non-climatic factors affect the depth of freezing propagation. Unlike the surface, which is influenced by the climate directly, the ground even at shallow depth receives a climatic signal that is substantially modified by edaphic processes, contributing to highly localized thermal sensitivities of the ground to climatic forcing. Subsurface properties, soil moisture, and snow and vegetation covers influence the depth of freezing. Topography also plays an important role in establishing the ground thermal regime. It is an important determinant of the amount of heat received by the ground surface, affects the distribution of snow and vegetation, and influences the surface and subsurface moisture regimes. As a result, the ground temperature and the related depth of freezing propagation are characterized by very high variability over short lateral distances. The data used for analysis by Frauenfeld and Zhang are single-point measurements obtained from a network of stations sparsely distributed over a very large spatial domain. Since no variability in edaphic conditions was considered, the presented results should be interpreted with some degree of caution. In addition, long-term soil observations at a single point using unautomated techniques unavoidably cause site disturbance, which may significantly modify the ground thermal regime over time. I would like to emphasize that the generalized continental trend in the depth of seasonal freezing presented by Frauenfeld and Zhang is very likely associated with changes in atmospheric forcing. However, any long-term continental trends of such a spatially heterogeneous and sensitive parameter as shallow soil temperature potentially include a significant non-climatic component. Although the single-point temperature data used by Frauenfeld and Zhang might not be sufficient to fully evaluate the localized effects on the overall trend, they are a terrific asset for further studies on climate and ground thermal regime. Detailed spatial assessment of the available ground temperature records over relatively homogeneous regions is a necessary next step in the assessment of climate-induced changes in seasonally frozen ground. Such an analysis is likely to show significant regional differences in long-term freeze propagation trends over Northern Eurasia and reveal region-specific sensitivities of the ground thermal regime to climatic forcing. References Brown R D and Robinson D A 2011 Northern hemisphere spring snow cover variability and change over 1922–2010 including an assessment of uncertainty Cryosphere 5 219–29 Callaghan T V, Tweedie C E and Webber P J 2011 Multi-decadal changes in tundra environments and ecosystems: the International Polar Year-Back to the Future Project (IPYBTF) AMBIO 40 555–7 Frauenfeld O W and Zhang T 2011 An observational 71-year history of seasonally frozen ground changes in the Eurasian high latitudes Environ. Res. Lett. 6 044024 Frauenfeld O W, Zhang T, Barry R G and Gilichinsky D 2004 Interdecadal changes in seasonal freeze and thaw depths in Russia J. Geophys. Res. 109 D5101 Gilichinsky D A et al 2000 Use of the data of hydrometeorological survey for century history of soil temperature trends in the seasonally frozen and permafrost areas of Russia Earth Cryosp. 4 59–66 (in Russian) Riseborough D, Shiklomanov N I, Etselmuller B and Gruber S 2008 Recent advances in permafrost modeling Permafr. Pereglac. Process. 19 137–56 Romanovsky V E et al 2010 Thermal state of permafrost in Russia Permafr. Periglac. Process. 21 136–55 Schuur E A G et al 2008 Vulnerability of permafrost carbon to climate change: implications for the global carbon cycle Bioscience 58 701–14 Serreze M C and Francis J A 2006 The Arctic amplification debate Clim. Change 76 241–64 Shiklomanov N I, Nelson F E, Streletskiy D A, Hinkel K M and Brown J 2008 The circumpolar active layer monitoring (CALM) program: data collection, management, and dissemination strategies Proc. of the 9th International Conf. on Permafrost (Fairbanks, AK, 29 June–3 July 2008) vol 1, pp 1647–52 Zhao L, Ping C L, Yang D, Cheng G, Ding Y and Liu S 2004 Changes of climate and seasonally frozen ground over the past 30 years in Qinghai-Xizang (Tibetan) Plateau, China Glob. Planet. Change 43 19–31