Congratulations to Dr. Portnov who recently defended his thesis Role of subsea permafrost and gas hydrate in postglacial Arctic methane releases.
Text: Maja Sojtaric
Focus area of research in the doctoral thesis defended by CAGE candidate Aleksey Portnov at UiT The Arctic University of Tromsø, is subsea permafrost in South Kara Sea, more specifically the shallow area offshore Siberian West Yamal Peninsula. It was previously proposed that the permafrost in the Kara Sea, and other Arctic areas, extends to water depths up to 100 meters, creating a seal that methane stored underneath cannot bypass. Portnov and collegues have found that the West Yamal shelf is leaking, profoundly, at depths much shallower than that.
Significant amount of methane gas is leaking at depths between 20 and 50 meters. This suggests that a continuous permafrost seal is much smaller than proposed. Close to the shore the permafrost seal may be few hundred meters thick, but tapers off towards 20 meters water depth. And it is fragile. Portnov used mathematical models to map the evolution of the permafrost, and thus calculate its degradation since the end of the last ice age. The evolution of permafrost gives indication to what may happen to it in the future.