Retrogressive thaw slumps (RTSs) are spectacular landforms that occur due to the thawing of ice-rich permafrost or melting of massive ground ice, often in hillslope terrain. RTSs occur in the Arctic, the subarctic, and high mountain (Qinghai–Tibet Plateau) permafrost regions and are observed to expand in size and number due to climate warming. As the observation of RTSs is receiving more and more attention due to their important role in permafrost thaw; impacts on topography; mobilization of sediment, carbon, nutrients, and contaminants; and their effects on downstream hydrology and water quality, the thematic breadth of studies increases and scientists from different scientific backgrounds and perspectives contribute to new RTS research. At this point, a wide range of terminologies originating from different scientific schools is used, and we identified the need to provide an overview of variable characteristics of RTSs to clarify terminologies and ease the understanding of the literature related to RTS processes, dynamics, and feedbacks. We review the theoretical geomorphological background of RTS formation and landform characteristics to provide an up-to-date understanding of the current views on terminology and underlying processes. The presented overview can be used not only by the international permafrost community but also by scientists working on ecological, hydrological, and biogeochemical consequences of RTS occurrence and by remote-sensing specialists developing automated methods for mapping RTS dynamics. The review will foster a better understanding of the nature and diversity of RTS phenomena and provide a useful base for experts in the field but also ease the introduction to the topic of RTSs for scientists who are new to it.

A classification of cryogenic-landslide landforms is developed for mapping their distribution and dynamics. It is based on the previously suggested classification subdividing cryogenic landsliding into two main types: cryogenic translational landslides (or active-layer detachment slides), and cryogenic earth flows (or retrogressive thaw slumps). The increased proportion of retrogressive thaw slumps compared to active layer detachments in the North of West Siberia in the last decade creates the need for an expanded classification of cryogenic earth flows. One of the important issues is separating the process of landsliding and resulting landforms, which in English are covered by one term ‘retrogressive thaw slump’. In dealing with the landforms, we distinguish (1) open and (2) closed ones. Open cryogenic-landslide landforms are those formed by the retreating of the coast bluff due to the thaw of ice or ice-rich deposits with an additional impact from wave or stream action. Closed cryogenic-landslide landforms are those initiated on a slope landward, and thawed material is delivered to the coast or stream through an erosional channel. Morphologically we distinguish thermocirques and thermoterraces depending on the shape of the retreating headwall, crescent or linear, respectively. An important issue is the type of ground ice subjected to thaw: tabular, ice-wedge or constitutional ground ice are distinguished. Landforms can be active, stabilized or ancient. One can find both single landforms and their combination. The classification is based on a significant amount of field studies and interpretation of remote sensing data. Mapping of the cryogenic-landslide landforms is suggested using the proposed classification and indication features. The classification is based on the experience obtained mainly in the north of West Siberia. Applying it to other regions may require additional studies.

Permafrost thaw disrupts ecosystems, hydrology, and biogeochemical cycles, reinforcing climate change through a positive permafrost-carbon feedback loop. Thaw can be gradual, deepening the active layer, or abrupt, triggering thermokarst, thermo-erosion, or thermodenudation. Retrogressive thaw slumps (RTSs) are a key manifestation of abrupt permafrost thaw. Yet, their distribution, scale, and environmental controls in the West Siberian Arctic remain poorly understood, further complicated by their rapid evolution. This study presents an extensive update of the West Siberian RTS inventory through manual mapping using high-resolution, multi-source, multi-year recent (2016-2023) satellite basemaps (ESRI, Google Earth, and Yandex Maps). We developed an RTS classification capturing key environmental parameters, including morphology, spatial organization, terrain position, and associated relief-forming concurrent processes. The dataset comprises 6168 classified RTS landforms, integrating newly mapped sites with previously reported occurrences to provide a comprehensive view of a 445226 km² region covering the Yamal, Gydan, and Tazovsky peninsulas. The collected data underwent manual filtering and verification, leveraging local field experience and observations from key sites to reduce uncertainty and minimize false positives. Accuracy analysis, performed by comparing the dataset with various field datasets collected across the peninsulas, confirmed high accuracy (>90%) for RTS identification. The dataset likely underestimated the distribution of small RTSs due to the resolution limitations of remote sensing data, hence generally providing a conservative estimate. This dataset serves as a valuable resource for diverse research fields, including ecology, biogeochemistry, geomorphology, climatology, permafrost science, and natural hazard assessment. Additionally, it provides a crucial reference dataset for machine learning applications, enhancing upcoming remote sensing classification and predictive modeling approaches.

Climate-induced changes contribute to the thawing of ice-rich permafrost in the Arctic, which leads to the release of large amounts of organic carbon into the atmosphere in the form of greenhouse gases, mainly carbon dioxide and methane. Ground ice constitutes a considerable volume of the cryogenically sequestered labile dissolved organic carbon (DOC) subjected to fast mineralization upon thawing. In this work, we collected a unique geochemical database of the ground and glacier ice comprising the samples from various geographic locations in the Russian Arctic characterized by a variety of key parameters, including ion composition, carbon-bearing gases (methane and carbon dioxide), bulk biogeochemical indicators, and fluorescent dissolved organic matter (DOM) fractions. Our results show that interaction with solid material—such as sediments, detritus, and vegetation—is likely the overriding process in enrichment of the ground ice in all the dissolved compounds. Terrigenous humic-like dissolved organic matter was predominant in all the analyzed ice samples except for glacier ice from Bolshevik Island (the Severnaya Zemlya archipelago) and pure (with low sediment content) tabular ground ice from western Yamal. The labile protein-like DOM showed no correlation to humic components and was probably linked to microbial abundance in the ground ice. The sum of the fluorophores deconvoluted by PARAFAC strongly correlates to DOC, which proves the potential of using this approach for differentiation of bulk DOC into fractions with various origins and biogeochemical behaviors. The pure tabular ground ice samples exhibit the highest rate of fresh easily degradable DOM in the bulk DOC, which may be responsible for the amplification of permafrost organic matter decomposition upon thawing.

Permafrost thaw disrupts ecosystems, hydrology, and biogeochemical cycles, reinforcing climate change through a positive permafrost-carbon feedback loop. Thaw can be gradual, deepening the active layer, or abrupt, triggering thermokarst, thermo-erosion, or thermodenudation. Retrogressive thaw slumps (RTSs) are a key manifestation of abrupt permafrost thaw. Yet, their distribution, scale, and environmental controls in the West Siberian Arctic remain poorly understood, further complicated by their rapid evolution. This study presents an extensive update of the West Siberian RTS inventory through manual mapping using high-resolution, multi-source, multi-year recent (2016–2023) satellite basemaps (ESRI, Google Earth, and Yandex Maps). We developed an RTS classification capturing key environmental parameters, including morphology, spatial organization, terrain position, and associated relief-forming concurrent processes. The dataset comprises 6168 classified RTS landforms, integrating newly mapped sites with previously reported occurrences to provide a comprehensive view of a 445 226 km² region covering the Yamal, Gydan, and Tazovsky peninsulas. The collected data underwent manual filtering and verification, leveraging local field experience and observations from key sites to reduce uncertainty and minimize false positives. Accuracy analysis, performed by comparing the dataset with various field datasets collected across the peninsulas, confirmed high accuracy (>90 %) for RTS identification. The dataset likely underestimated the distribution of small RTSs due to the resolution limitations of remote sensing data, hence generally providing a conservative estimate. This dataset serves as a valuable resource for diverse research fields, including ecology, biogeochemistry, geomorphology, climatology, permafrost science, and natural hazard assessment. Additionally, it provides a crucial reference dataset for machine learning applications, enhancing upcoming remote sensing classification and predictive modeling approaches. The dataset is available from Nesterova et al. (2025; https://doi.org/10.1594/PANGAEA.974406).

Т. In recent decades, the distribution and activation of thermodenudation, which leads to the formation of specific landforms — thermocirques (also referred to as retrogressive thaw slumps, RTS), have been intensively studied. In different regions of the cryolithozone and at different time intervals, both activation and stabilization of thermocirques are observed. As a rule, studies focus on the climatic controls of the phenomena observed, the environmental controls are discussed less often. This study presents an analysis of the dynamics of thermocirques in relation to the relief features in a specific key area of Central Yamal. To achieve this aim, the spatial distribution of thermocirques at different geomorphological levels is considered based on multi-temporal remote sensing data. Satellite images obtained in 2009, 2018, and 2023, as well as a global digital elevation model (ArcticDEM), were used. We outlined five geomorphic levels and determined their parameters: area, altitude, steepness, and the aspect of the slopes. Thermocirques were identified in the images and their parameters were measured. The dynamics of the thermocirques were analyzed by their number, area, length, width, slope aspect and angle for the periods 2009–2018 and 2018–2023, and for 14 years in total, separately for each geomorphic level. It was found that thermocirques predominate on the slopes of the III alluvial-marine plain, 5–12° steep. In 14 years, the total area of thermocirques increased by 296 %, and their number — by 61 %. A larger increase in the total area and number of thermocirques occurred during the period 2009–2018 in response to climate extremes in 2012 and 2016. Thermocirques that face west cover a higher total area, partly due to the predominance of such slopes over the area of the key site. In all the years of observation, the average areas and lengths of thermocirques are maximum on south-facing slopes. Some of the results are close to those obtained in other regions of Russia and in North America. In many of the areas studied, the increase in the total area of thermocirques exceeded the increase in their number, which means that the expansion of the existing forms prevails over the inception of the new ones. The discrepancies observed in different studies in the results of assessing the effect of relief on thermocirques are due to both the regional features and differences in satellite imagery and methods of its processing.