ИСТИНА

The Arctic is warming dramatically, with potentially catastrophic impacts on climate through rapid mobilization of the labile reservoirs of carbon sequestered in permafrost. The top candidate to move substantial amounts of carbon from land and ocean to atmosphere on decadal-century timescales is thawing permafrost in the Arctic. One possible feedback is release of previously produced methane (CH4) preserved within seabed deposits, such as natural gas fields and coal beds, and collapse of the CH4 hydrates underlying the Arctic seabed. Thus, the state of the Arctic shelf cryolithozone and its evolution continue to be priority areas in geocryological and geoecological research nowadays. Increased heat flow from the subsurface and modern climatic changes contribute to active degradation of submarine permafrost, that leads to the emergence of localized thawing zones. Such zones can act as discharge pathways for deep fluids and can also lead to destabilization of gas hydrate strata. Given the importance of these processes in the global carbon cycle and their impact on the geo-environmental situation, a comprehensive study of permafrost dynamics is required. �� number of studies of the patterns of permafrost spreading were carried out using the Time Domain Electromagnetic method (TDEM) during expeditions on the Arctic shelf in the period from 2013 to 2024. This method, based on recording the temporal decline of the electromagnetic field, provides high accuracy in determining the spatial distribution of electrical resistivity, that makes it possible to effectively map permafrost strata and localize thawing zones. Detailed geophysical studies were carried out at the micro-polygons in the Laptev and East Siberian Seas, where massive release of bubbling methane was discovered. The revealed areas of local electrical resistivity decrease reflect variability in the permafrost structure and are interpreted as areas of existence of through permafrost thawing bulbs called taliks, presumably acting as pathways of deep methane filtration. The spatial analysis of the electrical resistivity distribution has revealed good correlation between the structure of subsea permafrost with taliks and areas of bubble methane release. This correlation indicates that permafrost degradation and formation of local talik zones lead to activation of deep fluid release accompanied with massive methane fluxes into the atmosphere. The results obtained confirm the existence and development of submarine permafrost degradation zones, including through taliks, on the Arctic shelf. Formation of thawed areas within the subsea permafrost sometimes leads to abrupt gas release from sediments with formation of craters. That increases geoecological risks. The TDEM method has demonstrated high efficiency in mapping the subsea permafrost table and local taliks. Application of this approach is an effective tool for express monitoring of the Arctic shelf cryolithozone dynamics and geo-hazards.