Stepan P. Varlamov

By analyzing the last 50–60 years of climate changes in Arctic and Subarctic Yakutia, we have identified three distinct periods of climate development. The cold (1965–1987), pre-warming (1988–2004), and modern warming (2005–2023) periods are clearly identifiable. Yakutia’s Arctic and Subarctic regions have experienced mean annual air temperature increases of 2.5 °C and 2.2 °C, respectively, compared to the cold period. The thawing index rose by an average of 171–214 °C-days, while the freezing index dropped by an average of 564–702 °C-days. During the pre-warming period, all three characteristics show a minor increase in warmth. Global warming intensified between 2005 and 2023, resulting in elevated permafrost temperatures and a deeper active layer. Monitoring data from the Tiksi site show that warming has been increasing at different depths since the mid-2000s. As a result, the permafrost temperature increased by 1.7 °C at a depth of 10 m and by 1.1 °C at a depth of 30 m. Soil temperature measurements at meteorological stations and observations at CALM sites both confirm the warming of the permafrost. A permafrost–climatic zoning study was conducted in Arctic and Subarctic Yakutia. Analysis identified seven regions characterized by similar responses to modern global warming. These study results form the foundation for future research on global warming’s effects on permafrost and on how northern Yakutia’s environment and economy adapt to the changing climate.

Global climate has undergone significant changes in the past 50-60 years. The transition from stable climate conditions to current warming has significantly influenced permafrost landscapes and infrastructure in cold regions. Arctic and Subarctic landscapes had distinct reactions to these changes. The objective of this study is to analyze the regional aspects of climate and permafrost changes in Yakutia's Arctic and subarctic regions from the past 50-60 years. Our analysis focused on climate change patterns during different periods, including cold period, pre-warming, and modern warming. We analyzed data on mean annual air temperature, thawing and freezing indices, and precipitation. During these periods, we determined the reaction's characteristics in various landscape regions. The most significant impact on permafrost began in the mid-2000s, as our observations confirmed. Global warming directly causes permafrost temperature to rise, the active layer to thicken, and cryogenic processes to develop. The conducted research provides the information needed to study the effects of global warming on permafrost and adapt socio-economic conditions in northern Yakutia.

Pipelines are critical infrastructure for Yakutia, transporting vital supplies to communities in this vast northern region. The pipeline routes in central Yakutia traverse areas of ice-rich permafrost that is sensitive to temperature changes. This study examined the thermal state of permafrost in undisturbed and disturbed settings along the Lena River to Mundulakh Reservoir water pipeline and the Mastakh to Yakutsk gas pipeline and considered the effects of climatic fluctuations and surface disturbances (forest removal and wildfire) over the monitoring periods of 28 and 18 years, respectively. The geocryological conditions in the study area, as well as the methods of permafrost thermal monitoring, are described. The observation results demonstrated significant increases in the mean annual ground temperature in the upper permafrost layers, as well as in the active-layer thickness following fire and post-fire clearing. At some sites, progressive deepening of the active layer caused the formation of taliks and reached the top of massive ground ice, initiating permafrost degradation. The development of extreme ground temperatures in the layer of annual temperature fluctuations was analyzed according to the combination of seasonal and annual meteorological conditions and the type of anthropogenic impact. The research results can be extrapolated to similar anthropogenic landscapes.

This paper presents the results of long-term temperature monitoring at the Yakutsk and Zeleny Lug stations, which are experimental sites, for the thermal state of valley permafrost landscapes under the conditions of modern climate warming. An analysis of the long-term data from meteorological stations in the region clearly showed one of the highest trends of increase in the mean annual air temperature in the north of Russia. Here, we established quantitative regularities in the long-term variability of the ground temperature at the bottom of the active layer and at zero amplitude. The dynamics of the ground temperature of the layer of zero amplitude during climate warming indicate the thermal stability of permafrost. The main regulating factor of the thermal state of grounds in permafrost landscapes is short-term fluctuations in the regime of snow accumulation. Active layer thickness is characterized by low interannual variability, weak climate warming responses, and insignificant trends. The results of studies of the thermal regime of soils can be extended to the same types of valley landscapes in the Lena River, and are a reliable basis for predicting heat transfer in natural and disturbed landscapes.

This paper presents the results of 39 years of observations conducted at the Chabyda station to monitor the thermal state of permafrost landscapes under current climatic warming. The analysis of long-term records from weather stations in the region has revealed one of the highest increasing trends in mean annual air temperature in northern Russia. The partitioning of the energy balance in different landscape units within the study area has been analyzed. Quantitative relationships in the long-term variability of ground thermal parameters, such as the ground temperature at the bottom of the active layer and seasonal thaw depth, have been established. The ground temperature dynamics within the depth of zero annual amplitude indicates that both warm and cold permafrost are thermally stable. The short-term variability of the snow accumulation regime is the main factor controlling the thermal state of the ground in permafrost landscapes. The depth of seasonal thaw is characterized by low interannual variability and exhibits little response to climate warming, with no statistically significant increasing or decreasing trend. The results of the ground thermal monitoring can be extended to similar landscapes in the region, providing a reliable basis for predicting heat transfer in natural, undisturbed landscapes.

The history of permafrost landscape map compilation is related to the study of ecological problems with permafrost. Permafrost-landscape studies are now widely used in geocryological mapping. Permafrost-landscape classifications and mapping are necessary for studying the trends in development of the natural environment in northern and high-altitude permafrost regions. The cryogenic factor in the permafrost zone plays a leading role in the differentiation of landscapes, so it must be considered during classification construction. In this study, a map’s special content was developed using publications about Yakutian nature, archive sources from academic institutes, the interpretation of satellite images, and special field studies. Overlays of 20 types of terrain, identified by geological and geomorphological features, and 36 types of plant groupings, allowed the systematization of permafrost temperature and active layer thickness in 145 landscape units with relatively homogeneous permafrost-landscape conditions in the Sakha (Yakutia) Republic. This map serves as a basis for applied thematic maps related to the assessment and forecast of permafrost changes during climate warming and anthropogenic impacts.