First results of the multidisciplinary expedition onboard the R/V Akademik Nikolaj Strakhov in the Barents Sea in August–September 2018 are presented. Hydrophysical sounding has been carried out on 41 stations, sampling of bottom sediments has been done using both grab and gravity corer. As a result of the geophysical investigations, areas with manifestations of current dangerous natural processes are identified. Four seismic bottom stations have been installed in the Pechora Sea.

Приведены первые результаты комплексной экспедиции на научно-исследовательском судне «Академик Николай Страхов» в Баренцево море в августе–сентябре 2018 г. Проведено гидрофизическое зондирование на 41 станции, отобраны пробы донных осадков как с помощью дночерпателя, так и грунтовой трубкой. В результате геофизических исследований выявлены участки с проявлениями современных опасных природных процессов. Установлены 4 сейсмостанции в Печорском море.

The rates of subsea permafrost degradation and occurrence of gas-migration pathways are key factors controlling the East Siberian Arctic Shelf (ESAS) methane (CH 4 ) emissions, yet these factors still require assessment. It is thought that after inundation, permafrost-degradation rates would decrease over time and submerged thaw-lake taliks would freeze; therefore, no CH 4 release would occur for millennia. Here we present results of the first comprehensive scientific re-drilling to show that subsea permafrost in the near-shore zone of the ESAS has a downward movement of the ice-bonded permafrost table of ∼14 cm year −1 over the past 31–32 years. Our data reveal polygonal thermokarst patterns on the seafloor and gas-migration associated with submerged taliks, ice scouring and pockmarks. Knowing the rate and mechanisms of subsea permafrost degradation is a prerequisite to meaningful predictions of near-future CH 4 release in the Arctic.

In 2011 and 2012, the interdisciplinary oceanic cruises of the R/V Akademik M.A. Lavrent’ev and R/V Viktor Buinitskii were conducted in the framework of the project of targeted basic research of the Russian Foundation for Basic Research. These studies identified strong methane jets because of the degradation of submarine permafrost rocks (SPRs), which is related to paleogeographical and modern factors of formation of the upper sedimentary sequence and also to structural peculiarities of the Arctic region. Large gas and water volumes are formed at the expense of the SPR defrosting; move along the upper sedimentary shelf sequence and along the surface of one or another layer (from coastal warmed areas to cooler deep areas); and form horizontally elongated convective cells, which activates destruction even at negative bottom temperatures. The methane emission will increase and become massive during the continuing SPR degradation.

Sustained release of methane (CH(4)) to the atmosphere from thawing Arctic permafrost may be a positive and significant feedback to climate warming. Atmospheric venting of CH(4) from the East Siberian Arctic Shelf (ESAS) was recently reported to be on par with flux from the Arctic tundra; however, the future scale of these releases remains unclear. Here, based on results of our latest observations, we show that CH(4) emissions from this shelf are likely to be determined by the state of subsea permafrost degradation. We observed CH(4) emissions from two previously understudied areas of the ESAS: the outer shelf, where subsea permafrost is predicted to be discontinuous or mostly degraded due to long submergence by seawater, and the near shore area, where deep/open taliks presumably form due to combined heating effects of seawater, river run-off, geothermal flux and pre-existing thermokarst. CH(4) emissions from these areas emerge from largely thawed sediments via strong flare-like ebullition, producing fluxes that are orders of magnitude greater than fluxes observed in background areas underlain by largely frozen sediments. We suggest that progression of subsea permafrost thawing and decrease in ice extent could result in a significant increase in CH(4) emissions from the ESAS.

The problem of the current state of subaerial morphosculptures on the periglacial East Siberian Shelf is still debatable due to the lack of in situ data. Therefore, any new information contributes to the knowledge of the evolution of the Arctic environment. In view of this, a complex of interdisciplinary oceanological studies was carried out in the southeastern part of the Laptev Sea. Using a side-scan sonar, images of the bottom surface were made, which show the shape of low-center-polygonal relief of the part of the modern coastal lowland area in the coastal zone near the area under study. Possible factors controlling the state of this morphosculpture within the East Siberian Shelf area of interest are considered.