Arctic methane emissions permafrost thawing. Near the bottom of the first sinkhole, air contained unusually high concentrations of methane, according to tests conducted by the researchers. This hypothesis points to the destabilization of gas hydrates containing huge amounts of methane gas. According to researchers at Norway's Centre for Arctic Gas Hydrate (CAGE), through a process called geothermal heat flux, the Siberian permafrost which extends to the seabed of the Kara Sea, a section of the Arctic Ocean between the Yamal Peninsula and Novaya Zemlya, is thawing. According to a CAGE researcher, Aleksei Portnov, Methane hydrate is leaking in an area of at least
Severnaya Zemlya as Arctic lemming, which is present on all of the large islands and, in some places has been recorded to reach a density of 500 per km (1,300 per sq mi). The Arctic fox ("Alopex lagopus") has been known to den on the islands, with several hundred observed in the 1980s. Other mammals occasionally observed include the wolf ("Canis lupus"), the polar bear ("Ursus maritimus"), ermine ("Mustela erminea"), Arctic hare ("Lepus timidus"), and reindeer ("Rangifer tarandus"). The discovery of Severnaya Zemlya is the subject of Veniamin Kaverin's novel "The Two Captains" as well as its stage adaptation, "Nord-Ost". Severnaya Zemlya