Dmitry A. Streletskiy

Permafrost hydrology in changing climatic conditions: seasonal variability of stable isotope composition in rivers in discontinuous permafrost

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.

Permafrost, Infrastructure, and Climate Change: A GIS-Based Landscape Approach to Geotechnical Modeling

Abstract Increases in air temperature have occurred in most parts of the Arctic in recent decades. Corresponding changes in permafrost and the active layer have resulted in decreases in ground-bearing capacity, which may not have been anticipated at the time of construction in permafrost regions. Permafrost model was coupled with empirically derived solutions adopted from Soviet and Russian construction standards and regulations to estimate the bearing capacity of foundations under rapidly changing climatic conditions, in a variety of geographic and geologic settings. Changes in bearing capacity over the last 40 years were computed for large population and industrial centers within different physiographic and climatic conditions of the Russian Arctic. The largest decreases were found in city of Nadym, where the bearing capacity has decreased by more than 40%. A smaller, but considerable decrease of approximately 20% was estimated for Yakutsk and Salekhard. Spatial model results at a regional scale depict diverse patterns of changes in permafrost-bearing capacity in Northwest Siberia and the North Slope of Alaska. The most pronounced decreases in bearing capacity (more than 20%) are estimated for the southern part of permafrost zone where deformations of engineering structures can potentially be attributed to climate-induced permafrost warming.

Spatial variability of permafrost active-layer thickness under contemporary and projected climate in Northern Alaska

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 the climate data, the model was forced byfour sets of gridded air temperature fields used widely in spatial modeling applications. A series of calculations created a spectrum of possible solutions for ALT and associated probabilityranges for each grid cell. Results are presented as a series of maps depicting geographic patterns of contemporaryand future ALT for the North Slope of Alaska.

Climate Change and Stability of Urban Infrastructure in Russian Permafrost Regions: Prognostic Assessment based on GCM Climate Projections†

Abstract One of the most significant climate change impacts on arctic urban landscapes is the warming and degradation of permafrost, which negatively affects the structural integrity of infrastructure. We estimate potential changes in stability of Russian urban infrastructure built on permafrost in response to the projected climatic changes provided by six preselected General Circulation Models (GCMs) participated in the most recent Climate Model Inter‐comparison Project (CMIP5). The analysis was conducted for the entire extent of the Russian permafrost‐affected area. According to our analysis a significant (at least 25%) climate‐induced reduction in the urban infrastructure stability throughout the Russian permafrost region should be expected by the mid‐21st century. However, the high uncertainty, resulting from the GCM‐produced climate projections, prohibits definitive conclusion about the rate and magnitude of potential climate impacts on permafrost infrastructure. Results presented in this paper can serve as guidelines for developing adequate adaptation and mitigation strategy for Russian northern cities.

Chapter 10 – Permafrost Degradation

Climatic changes over the last 50 years resulted in a decrease of permafrost extent, an increase of permafrost temperature, and deepening of the active layer in numerous locations across the Arctic and High Mountainous environments. Permafrost degradation poses serious impacts ranging from local changes in topographic and hydrologic conditions, impacts on infrastructure and sustainability of northern communities, changes to vegetation and wildlife dynamics, and to global impacts on climate system. Hazards associated with permafrost degradation are exacerbated in areas of human activities, especially in large settlements with developed infrastructure in the Arctic. Unlike smaller communities, which have higher mobility, large population centers have to build in situ adaptive capacity to face environmental changes. Permafrost degradation can have severe socioeconomic consequences as most of the existing infrastructure will require expensive engineering solutions to maintain economic activities on permafrost.

Conquering the permafrost: urban infrastructure development in Norilsk, Russia

ABSTRACT 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 viable solutions to maintain city infrastructure. The analysis of Norilsk’s experiences with permafrost can potentially contribute to the development of sustainable practices for Arctic urbanization.

Climatic- and anthropogenic-induced land cover change around Norilsk, Russia

ABSTRACT 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 permafrost. Norilsk, Russia, the largest city built on permafrost north of the Arctic Circle, has a long history of development and industrial activity providing an opportunity to evaluate the climatic- and anthropogenic-induced land cover change. Land cover changes in three areas representative of natural and anthropogenic landscapes in the vicinity of Norilsk were examined over a 30 year period of documented warming focusing on three time periods corresponding to distinct socio-economic conditions: the mid- to late 1980s, the early 2000s, and the 2010s. Temperature increases resulted in consistent and significant greening and a slight increase in surface water extent in the nearby area unaffected by human activities. The areas modified by human activities within the city and downwind from local pollution sources experienced an expansion of barren ground due primarily to sulfur-dioxide-laden pollution. Subsequent decreases in emissions in this area correspond with marginal revegetation, or a likely process of secondary succession with the expansion of tall shrubs. These findings show that both climatic warming and industrial development exert significant influence on Arctic land covers.

Land Cover Change in the Lower Yenisei River Using Dense Stacking of Landsat Imagery in Google Earth Engine

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 cloudand 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.

Traditional Iñupiat Ice Cellars (SIĠḷUAQ) in Barrow, Alaska: Characteristics, Temperature Monitoring, and Distribution

Abstract 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 indicate that ice cellars are “failing” through mechanisms that include flooding and collapse, which are often attributed to climate change. In cooperation with local stakeholders, we instrumented five cellars to record internal air temperature in Barrow, Alaska. A decade of thermal monitoring (2005–2015) revealed little thermal change. A survey was also conducted to identify all known ice cellar locations in Barrow. A total of seventy‐one cellars were catalogued and mapped. The large number of catalogued cellars shows the importance and great potential loss for the Barrow community if widespread failures were to occur. Although climate change has considerable potential for affecting ice cellars, sediment chemistry, local hydrology, and urbanization are also important impacting factors.