Arctic coasts composed of frozen deposits are extremely sensitive to climate change and human impact. They retreat with average rates of 1–2 m per year, depending on climatic and permafrost conditions. In recent decades, retreat rates have shown a tendency to increase. In this paper, we studied the coastal dynamics of two key sites (Ural and Yamal coasts) of Baydaratskaya Bay, Kara Sea, where a gas pipeline had been constructed. Based on multi-temporal aerial and satellite imagery, we identified coastal erosion rates at several time lapses, in natural conditions and under human impact, and discussed their temporal variability. In addition to planimetric (m/yr), we calculated volumetric (m³/m/yr) retreat rates of erosional coasts using ArcticDEM. We also estimated the influence of geomorphology, lithology, and permafrost structure of the coasts on spatial variations of their dynamics. Erosional coasts of the Ural key site retreat with higher mean rates (1.2 m/yr and 8.7 m³/m/yr) as compared to the Yamal key site (0.3 m/yr and 3.7 m³/m/yr) due to their exposure to higher open sea waves, more complex lithology, higher ice content and lower coastal bluffs. Since the 1960s, coastal retreat rates have been growing on both coasts of Baydaratskaya Bay; we relate this effect with Arctic climate warming. From the 1960s to 2005, such growth was moderate, while in 2005–2016 it became rapid, which may be explained by the enhanced wave and thermal action or by the onset of industrial development. The adjacent coastal segments, originally accumulative, remained relatively stable from the 1960s to 2005. After 2005, a considerable part of them began to retreat as a result of changing weather conditions and/or increasing human impact.

Ogorodov S.A., Aleksyutita D.M. et al., 2020. Coastal erosion of the Russian Arctic: An overview. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 599-604. Coconut Creek (Florida), ISSN 0749-0208.An overview of 16 sites of coastal erosion monitoring at the fastest retreating key sites across the Russian Arctic was made. All of these coasts are composed by permafrost, creating specific conditions of their evolution and making them very sensitive to sea ice reduction and ice-free period increase along with the temperature growth, resulting from the ongoing climate change. Erosion of permafrost coasts is among the fastest destructive geomorphic processes in the Arctic. For each key area, data from literature on sediment composition, coastal morphology, permafrost properties and climate evolution were collected, assessed and compared. Rates of coastal retreat in the XX-XXI century derived from direct field measurements and processing of remotely sensed data were analyzed; mechanisms and drivers of coastal erosion were estimated. Patterns of spatial variability and temporal evolution of the coasts were suggested. The influence of different factors of coastal dynamics on thermodenudation (destruction of the bluffs during thawing of permafrost and ground ice) and thermoabrasion (erosion resulting from direct contact of waves with the frozen bluff) was estimated.

The duration of ice-free periods in different parts of the Arctic Ocean plays a great role in processes in the climate system and defines the most comfortable sea ice conditions for economic activity. Based on satellite-derived sea ice concentration data acquired by passive microwave instruments, we identified the spatial distribution of the dates of sea ice retreat (DOR), dates of sea ice advance (DOA), and the resulting ice-free period duration (IFP) between these days for the Kara and Laptev seas during 1979–2022. The monthly decline in sea ice extent was detected from June to October in both seas, i.e., during the whole ice-free period. The annual mean sea ice extent during 2011–2021 decreased by 19.0% and 12.8% relative to the long-term average during 1981–2010 in the Kara and Laptev seas, respectively. The statistically significant (95% confidence level) positive IFP trends were detected for the majority of areas of the Kara and Laptev seas. Averaged IFP trends were estimated equal to +20.2 day/decade and +16.2 day/decade, respectively. The observed DOR tendency to earlier sea ice melting plays a greater role in the total IFP extension, as compared to later sea ice formation related to the DOA tendency. We reveal that regions of inflow of warm Atlantic waters to the Kara Sea demonstrate the largest long-term trends in DOA, DOR, and IFP associated with the decrease in ice coverage, that highlights the process of atlantification. Also, the Great Siberian Polynya in the Laptev Sea is the area of the largest long-term decreasing trend in DOR.