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This paper presents the results of an acoustic survey carried out from the fast ice in the shallow waters of the East Siberian Arctic Shelf (ESAS) using a single beam echosounder. The aim of this paper is to demonstrate an improved approach to study seafloor seepages in the Arctic coastal zone with an echosounder calibrated on site. During wintertime field observations of natural rising gas bubbles, we recorded three periods of their increased activity with a total of 63 short-term ejections of bubbles from the seabed. This study presents quantitative estimates of the methane (CH4) flux obtained in wintertime at two levels of the water column: (1) at the bottom/water interface and (2) at the water/sea ice interface. In winter, the flux of CH4 transported by rising bubbles to the bottom water in the shallow part of the ESAS was estimated at ~19 g·m−2 per day, while the flux reaching the water/sea ice interface was calculated as ~15 g·m−2 per day taking into account the diffusion of CH4 in the surrounding water and the enrichment of rising bubbles with nitrogen and oxygen. We suggest that this bubble-transported CH4 flux reaching the water /sea ice interface can be emitted into the atmosphere through numerous ice trenches, leads, and polynyas. This CH4 ebullition value detected at the water/sea ice interface is in the mid high range of CH4 ebullition value estimated for the entire ESAS, and two orders higher than the upper range of CH4 ebullition from the northern thermocarst lakes, which are considered as a significant source to the atmospheric methane budget. [ABSTRACT FROM AUTHOR]

Three species belonging to the fern genus Ochotopteris E. Lebedev, including the new species O. lebedevii Herman et Domogatskaya, are revised, described and illustrated in this paper. The fossils come from Albian, Cenomanian, Turonian and Coniacian beds exposed at seven sites in North-Eastern Asia and Northern Alaska. These sites are located in the Cretaceous Arctic, with their palaeolatitudes ranging from 60° N to 80° N. The high endemism characteristic of the mid-Cretaceous Arctic flora is most probably due to adaptations in the globally distinctive Arctic conditions: the unique combination of temperatures, precipitation and the highly seasonal polar light regime. Being an endemic plant of the mid-Cretaceous Arctic, Ochotopteris ferns were adapted to a regional wet temperate to a wet warm temperate palaeoclimate accompanied by marked sunlight seasonality with a prolonged—up to several weeks—winter darkness and continuous summer daylight, also lasting for several weeks. The majority of the mid-Cretaceous Arctic plants were deciduous. Their predominant deciduousness was most probably due to the polar light seasonality: at the end of the growing season, some plants dropped their leaves or leafy shoots, whereas others—including Ochotopteris ferns—died back to rhizome systems. [ABSTRACT FROM AUTHOR]

Change in sea levels, be they isostatic or eustatic, impact humans and the paleogeography they inhabit. In this paper we examine paleogeography at Iqaluktuuq, a section of the Ekalluk River, Victoria Island, Nunavut, between Tahiryuaq (Ferguson Lake) and Wellington Bay. The area's isostatic rebound impacted the Ekalluk River's development and the use of the area by two essential subsistence resources, Arctic char (Salvelinus alpinus) and caribou (Rangifer tarandus). This, in turn, impacted the choices of Pre-Dorset, Middle and Late Dorset, and Thule/Inuit people regarding site locations. A new relative sea-level curve developed using calibrated radiocarbon dates on marine shells and terrestrial material from archaeological sites is produced for Iqaluktuuq. Based on the data, large scale (1:50,000) paleogeography maps are presented for the period of human occupation of Iqaluktuuq, 3100 calibrated years Before Present (B.P. cal) to present, revealing how paleogeography impacts people's settlement choices. [ABSTRACT FROM AUTHOR]

Provenance study plays an important role in paleogeographic and tectonic reconstructions. Detrital zircons are commonly used to identify sediment provenance; however, a wide range of detrital zircon ages in clastic rock often represent a fingerprint of reworked older terrigenous successions rather than ages of magmatism and metamorphism in the provenance area. This study focuses on the provenance of detrital rutile grains in the Triassic–Jurassic sandstones from Franz Josef Land and shows the importance of multiproxy approaches for provenance studies. Trace element data demonstrate that most rutile grains were sourced from metapelitic rocks, with a subordinate population having a metamafic origin. The Zr-in-rutile thermometer and U-Pb geochronology suggest that detrital rutile grains were predominantly derived from rocks that underwent amphibolite facies metamorphism during the Paleozoic era, with a predominance of the Carboniferous–Permian ages. Therefore, we suggest that the provenance area for the studied sandstones on Franz Josef Land has a similar geological history to the Taimyr region and Severnaya Zemlya archipelago. We propose that this crustal domain extends across the Kara Sea and forms the basement to the north and east of FJL, representing a proximal provenance for the studied Mesozoic terrigenous rocks. This domain experienced both Middle–Late Ordovician and Carboniferous–Permian metamorphism. The comparison of U-Pb dating and the geochemistry of rutile, U-Th/He, and U-Pb dating of zircons showed that detrital rutiles are the powerful toll in provenance restoration and can give additional constrains when a provenance area locates within collisional-convergent settings. [ABSTRACT FROM AUTHOR]

The surface of mountain glaciers is a place of accumulation of various biogenic organomineral and mineral compounds. As a result of intensive mass deglaciation of glaciers due to climate change and anthropogenic activity, this material can significantly affect the transformation of the landscape in the periglacial zone. Thus, this work considers the contamination of the surface of the Arctic, Antarctic, and Caucasian glaciers by priority pollutants. Atomic absorption spectroscopy was used to analyze trace elements (Cu, Zn, Ni, Cd, Pb) from cryoconite deposits. It was revealed that the cryoconite dust on the Ray-Iz glacier (Polar Urals) has a high level of nickel contamination, which comes to the glacier from local rock materials as a result of their weathering. The lowest concentrations of trace elements are found in one of the Arctic plots located at Mushketov and Aldegonda glaciers, the Caucasus, and the Antarctic, which is due to their relatively low content in the composition of rocks and the relatively low contribution of long-range transport of matter to the polar regions. Contamination of moraine sediments in the periglacial zone can make a significant contribution to the formation of the soil cover of these territories, the pollution of water bodies near the glacier, as well as affect the quality of life of the people living in the immediate vicinity of the mountain areas. [ABSTRACT FROM AUTHOR]

A correlation is observed between changes in the level of Earth's seismic activity and increments of the atmospheric methane concentration over the past 40 years. Trigger mechanisms are proposed for methane emissions and glacier collapse in polar regions. These mechanisms are due to deformation waves caused by large earthquakes in subduction zones located near the polar regions: the Aleutian and Kuril–Kamchatka subduction zones, closest to the Arctic, and the Antarctica–Chilean and Tonga–Kermadec–Macquarie subduction zones. Disturbances of the lithosphere are transmitted over the distances of 3000–4000 km and more at a speed of about 100 km/year. Additional associated stresses come to the Arctic and Antarctica several decades after the occurrence of large earthquakes. In the Arctic zone, additional stresses affect the low-permeability structure of gas bearing sedimentary strata, causing increased methane emission and climate warming. In West Antarctica, deformation waves could trigger the acceleration and intensive collapse of West Antarctic glaciers, which has been observed since the 1970s. These waves are also capable of activating dormant volcanoes located under the sheet glaciers of West Antarctica, leading to an increase in heat flux, to the melting of ice at the glaciers' base, and to their accelerated sliding towards the ocean, as is happening with the Thwaites Glacier. [ABSTRACT FROM AUTHOR]

Knowledge of permafrost structure, with accumulations of free natural gas and gas hydrates, is indispensable for coping with spontaneous gas emission and other problems related to exploration and production drilling in Arctic petroleum provinces. The existing geophysical methods have different potentialities for imaging the permafrost base and geometry, vertical fluid conduits (permeable zones), taliks, gas pockets, and gas hydrate accumulations in the continental Arctic areas. The synthesis of data on cryological and geological conditions was the basis for a geophysical–geological model of northern West Siberia to a depth of 400 m, which includes modern permafrost, lenses of relict permafrost with hypothetical gas hydrates, and a permeable zone that may be a path for the migration of gas–water fluids. The model was used to model synthetic seismic, electrical resistivity tomography (ERT), and transient electromagnetic (TEM) data, thus testing the advantages and drawbacks of the three methods. Electrical resistivity tomography has insufficient penetration to resolve all features and can run only in the summer season. Seismic surveys have limitations in mapping fluid conduits, though they can image a horizontally layered structure in any season. Shallow transient electromagnetic (sTEM) soundings can image any type of features included into the geological model and work all year round. Thus, the best strategy is to use TEM surveys as the main method, combined with seismic and ERT data. Each specific method is chosen proceeding from economic viability and feasibility in the specific physiographic conditions of mountain and river systems. [ABSTRACT FROM AUTHOR]

Trigger mechanisms are proposed for gas hydrate decomposition, methane emissions, and glacier collapse in polar regions. These mechanisms are due to tectonic deformation waves in the lithosphere–asthenosphere system, caused by large earthquakes in subduction zones, located near the polar regions: the Aleutian arc, closest to the Arctic, and the Antarctica–Chilean and Tonga–Kermadec–Macquarie subduction zones. Disturbances of the lithosphere are transmitted over long distances (of the order of 2000–3000 km and more) at a speed of about 100 km/year. Additional stresses associated with them come to the Arctic and Antarctica several decades after the occurrence of seismic events. On the Arctic shelf, additional stresses destroy the microstructure of metastable gas hydrates located in frozen rocks at shallow depths, releasing the methane trapped in them and leading to filtration and emissions. In West Antarctica, these wave stresses lead to decreases in the adhesions of the covered glaciers with underlying bedrock, sharp accelerations of their sliding into the sea, and fault occurrences, reducing pressure on the underlying rocks containing gas hydrates, which leads to their decomposition and methane emissions. [ABSTRACT FROM AUTHOR]

Conventional scholarship long held that rock fracturing from physical processes dominates over chemical rock decay processes in cold climates. The paradigm of the supremacy of cold-climate shattering was questioned by Rapp's discovery (1960) that the flux of dissolved solids leaving a Kärkevagge, Swedish Lapland, watershed exceeded physical denudation processes. Many others since have gone on to document the importance of chemical rock decay in all cold climate landscapes, using a wide variety of analytical approaches. This burgeoning scholarship, however, has only generated a few nanoscale studies. Thus, this paper's purpose rests in an exploration of the potential for nanoscale research to better understand chemical processes operating on rock surfaces in cold climates. Samples from several Antarctica locations, Greenland, the Tibetan Plateau, and high altitude tropical and mid-latitude mountains all illustrate ubiquitous evidence of chemical decay at the nanoscale, even though the surficial appearance of each landscape is dominated by "bare fresh rock." With the growing abundance of focused ion beam (FIB) instruments facilitating sample preparation, the hope is that that future rock decay researchers studying cold climates will add nanoscale microscopy to their bag of tools. [ABSTRACT FROM AUTHOR]

The partially correlative Alaskan dinosaur-bearing Prince Creek Formation (PCF), North Slope, lower Cantwell Formation (LCF), Denali National Park, and Chignik Formation (CF), Aniakchak National Monument, form an N–S transect that, together, provides an unparalleled opportunity to examine an ancient high-latitude terrestrial ecosystem. The PCF, 75–85° N paleolatitude, had a Mean Annual Temperature (MAT) of ~5–7 °C and a Mean Annual Precipitation (MAP) of ~1250 mm/year. The LCF, ~71° N paleolatitude, had a MAT of ~7.4 °C and MAP of ~661 mm/year. The CF, ~57° N paleolatitude, had a MAT of ~13 °C and MAP of ~1090 mm/year. The relative abundances of the large-bodied herbivorous dinosaurs, hadrosaurids and ceratopsids, vary along this transect, suggesting that these climatic differences (temperature and precipitation) played a role in the ecology of these large-bodied herbivores of the ancient north. MAP played a more direct role in their distribution than MAT, and the seasonal temperature range may have played a secondary role. [ABSTRACT FROM AUTHOR]

Freezing and thawing of the land surface affects ecosystem and hydrological processes, the geotechnical properties of soil and slope stability. Currently, available datasets on land surface state lack either sufficient temporal or spatial resolution to adequately characterize the complexity of freeze/thaw transition period dynamics. Surface state changes can be detected using microwave remote sensing methods. Data available from scatterometer and Synthetic Aperture Radar (SAR) sensors have been used in the past in regional- to continental-scale approaches to monitor freeze/thaw transitions. This study aims to identify temporal and spatial patterns in freeze/thaw dynamics associated with the issue of differing temporal and spatial resolutions. For this purpose, two datasets representing the timing of freeze/thaw cycles at different resolutions and spatial extents were chosen. The used Advanced SCATterometer (ASCAT) Surface State Product offers daily circumpolar information from 2007-2013 for a 12.5-km grid. The SAR freeze/thaw product offers information of day of thawing and freezing for the years 2005-2010 with a nominal resolution of 500mand a temporal resolution of up to twice per week. In order to assess the importance of scale when describing temporal and spatial patterns of freeze/thaw processes, the two datasets were compared for spring and autumn periods for the maximum number of overlapping years 2007-2010. The analysis revealed non-linear landscape specific relationships between the two scales, as well as distinct differences between the results for thawing and re-freezing periods. The results suggest that the integration of globally available high temporal resolution scatterometer data and higher spatial resolution SAR data could be a promising step towards monitoring surface state changes on a seasonal, as well as daily and circumpolar, as well as local scale. [ABSTRACT FROM AUTHOR]

The amplified warming of the Arctic is one of several factors influencing atmospheric dynamics. In this work, we consider a series of numerical experiments to identify the role of Arctic sea ice reduction in affecting climate trends in the Northern Hemisphere. With this aim in mind, we use two independent mechanisms of ice reduction. The first is traditionally associated with increasing the concentration of carbon dioxide in the atmosphere from the historic level of 360 ppm to 450 ppm and 600 ppm. This growth increases air temperature and decreases the ice volume. The second mechanism is associated with a reduction in the reflectivity of ice and snow. We assume that comparing the results of these two experiments allows us to judge the direct role of ice reduction. The most prominent consequences of ice reduction, as a result, are the weakening of temperature gradient at the tropopause level in mid-latitudes; the slower zonal wind at 50–60° N; intensification of wave activity in Europe, Western America, and Chukotka; and its weakening in the south of Siberia and Kazakhstan. We also consider how climate change may alter regimes such as blocking and stationary Rossby waves. The study used the INM-CM48 climate system model. [ABSTRACT FROM AUTHOR]

Micromorphological investigation of soils is a powerful tool for studying the transformation of soils under the influence of various weathering mechanisms. In the Arctic region, under the influence of seasonal freezing/thawing processes, cryohydration is the leading type of weathering. Soils of different-aged islands of the Lena River Delta were investigated. Thin sections of soils were analyzed using a polarizing microscope Leica DM750P (Leica Camera AG, Wetzlar, Germany). X-ray fluorescence analysis was used to determine the chemical composition of the soils. As a result of the work, the rate of weathering of soil minerals was estimated, soil fabric was considered, as well as the chemical composition of the soil. The accumulation of poorly sorted circular striated sand due to active influence of the Lena River was noted on young soil from Samoylov isl. The formation of biogenic sand-silt crumb aggregates was noted at more ancient sites. Physical weathering of soil minerals under the influence of cryogenic processes has been noted. [ABSTRACT FROM AUTHOR]

This article describes the results of an Arctic expedition studying the new giant gas blowout crater in the north of Western Siberia, in the central part of the Yamal Peninsula in 2020. It was named C17 in the geoinformation system "Arctic and the World Ocean" created by the Oil and Gas Research Institute of the Russian Academy of Sciences (OGRI RAS). On the basis of remote sensing, it can be seen that the formation of the crater C17 was preceded by a long-term growth of the perennial heaving mound (PHM) on the surface of the third marine terrace. Based on the interpretation of satellite images, it was substantiated that the crater C17 was formed in the period 15 May–9 June 2020. For the first time, as a result of aerial photography from inside the crater with a UAV, a 3D model of the crater and a giant cavity in the ground ice, formed during its thawing from below, was built. The accumulation of gas, the pressure rise and the development of gas-dynamic processes in the cavity led to the growth of the PHM, and the explosion and formation of the crater. [ABSTRACT FROM AUTHOR]

The White Sea is a small shallow semi-closed sea in the North-West of Russia. It is strongly affected by induced tides, so the tidal motion dominates in the sea. Sea ice is seasonal and the water salinity is less than in the neighbouring Barents sea due to strong river discharge. We review the sources of in-situ and satellite data that are available for the sea, and describe those few numerical models, together with the challenges that are faced. We focus on the large-scale circulation and thermohaline fields, but also cover sea ice, river runoff, and pelagic biogeochemical data. [ABSTRACT FROM AUTHOR]

A seismogenic trigger mechanism is proposed to explain the abrupt climate warming phases in the Arctic as a result of strong mechanical disturbances in the marginal region of the Arctic lithosphere. Those disturbances might have been caused by great earthquakes in the Aleutian subduction zone, and slowly propagated across the Arctic shelf and adjacent regions, triggering the methane release from permafrost and metastable gas hydrates, followed by greenhouse gas emissions into the atmosphere. The proposed mechanism is based on the identified correlation between the series of the great earthquakes in the Aleutian island arc, which occurred in the early and middle of the 20th century, and the two phases of sharp climate warming, which began in 1920 and 1980. There is a 20-year time lag between these events, which is explained by the time of arrival of deformation waves in the lithosphere (propagating with a velocity of about 100 km per year) at the Arctic shelf and adjacent land from the Aleutian subduction zone, the region of their generation. The trigger mechanism causing the methane release from permafrost and metastable gas hydrates is related to the destruction of micro-sized ice films covering gas hydrate particles, the elements highly important for hydrate self-preservation, as well as destruction of gas-saturated micropores in permafrost rocks due to the slight additional stresses associated with deformation waves, and thus emergence of conditions favorable for gas filtration and its subsequent emission. [ABSTRACT FROM AUTHOR]

This article describes the main results of two Arctic expeditions in 2017–2018 to study the Seyakha Crater in the north of Western Siberia, Yamal Peninsula. It was formed on a place of a pingo-like feature (PLF) by huge blowout, self-ignition, and explosion of gas on 28 June 2017. In 2018, for the first time, the integration of geophysical studies on the Yamal Peninsula revealed in detail an Arctic gas-blowout crater within a river channel and adjacent land with permafrost. On the basis of unmanned aerial vehicle photography, echo sounding, and ground penetrating radar survey data processing, a 3D digital elevation model (DEM) of the crater and the structure of near-surface deposits was created. A previously unknown uplift inside the permafrost layers, probably connected with the processes of gas chamber formation, was revealed. A long period of continuous gas emission (mainly, biogenic methane) from the Seyakha C11 Crater (2017–2019) and other existing data show evidence for a gas-dynamic mechanism of the PLF growth and a volcanic type of eruption. [ABSTRACT FROM AUTHOR]

Permafrost degradation of coastal and marine sediments of the Arctic Seas can result in large amounts of methane emitted to the atmosphere. The quantitative assessment of such emissions requires data on variability of methane content in various types of permafrost strata. To evaluate the methane concentrations in sediments and ground ice of the Kara Sea coast, samples were collected at a series of coastal exposures. Methane concentrations were determined for more than 400 samples taken from frozen sediments, ground ice and active layer. In frozen sediments, methane concentrations were lowest in sands and highest in marine clays. In ground ice, the highest concentrations above 500 ppmV and higher were found in massive tabular ground ice, with much lower methane concentrations in ground ice wedges. The mean isotopic composition of methane is −68.6‰ in permafrost and −63.6‰ in the active layer indicative of microbial genesis. The isotopic compositions of the active layer is enriched relative to permafrost due to microbial oxidation and become more depleted with depth. Ice-rich sediments of Kara Sea coasts, especially those with massive tabular ground ice, hold large amounts of methane making them potential sources of methane emissions under projected warming temperatures and increasing rates of coastal erosion. [ABSTRACT FROM AUTHOR]