Permafrost is soil that has been frozen for at least two years but most have been frozen for tens of thousands of years. The ground is quite fertile, full of the remnants of ancient vegetation and animal species, many of whom are extinct. The frozen soils top layer can thaw enough to support plants such as moss, lichens, grasses, and wildflowers.
Melting permafrost releases methane or CO2 as the composition of the soil begins to decompose. Methane is thirty times more potent than CO2 and is released when there is no oxygen in saturated soil.
The top layer melting has become sufficient enough that it is more friendly for invasive shrubs and small trees to change the landscape of the Arctic. The process has become so typical that it has “morphed into its own verb”, shrubification.
Submarine permafrost, however, is soil that has been submerged since the last interglacial. The inundated permafrost layer is also warming at a worrisome pace.
Alfred-Wegener-Institut provides a brief explanation of the submarine permafrost.
Subsea permafrost in the Arctic is generally relict terrestrial permafrost, inundated after the last glaciation and now degrading under the overlying shelf sea. Permafrost may, however, also form when the sea is shallow, permitting sediment freezing through bottom-fast winter sea ice. Although maps based on observations exist for parts of the Canadian Beaufort Sea, we know little about the distribution of submarine permafrost for most of the shallow Arctic Shelf, over 80% of which lies offshore of Eastern Siberia. Degradation rates of the ice-bearing permafrost following inundation have been estimated to be 1 to 20 cm per year on the East Siberian Shelf and 1 to 4 cm per year in the Alaskan Beaufort Sea.
SNIP
Submarine permafrost is similar to its terrestrial counterpart, but lies beneath the coastal seas. And as with terrestrial permafrost, subsea permafrost is a substantial reservoir and/or a confining layer for gas and for gas hydrates. As submarine permafrost thaws, this gas is released and can perhaps increase atmospheric greenhouse gas concentration.
In a separate article, The Alfred Wegener Institute reports that scientists have now been able to “model the distribution of submarine permafrost underneath the entire Arctic seabed”. The study was published in April of 2019 in the Journal of Geophysical Research: Oceans. They found that that submarine permafrost is “more widely distributed than previously thought and is almost all getting thinner”.
Trouble in Siberia.
Tass News Agency writes on a new study that experts from Skoltech, the Tomsk Polytechnic University and the Academy of Sciences’ Pacific Oceanology Institute on the East Siberian Arctic coastal shelf.
Saltwater intrusion is having a destabilizing effect on the submarine permafrost along coastal Arctic shelves.
MOSCOW, May 24. /TASS/. Russian scientists opened a new mechanism, explaining influence from salt migration emerging from decomposition of huge gas (methane) hydrates reserves on the Arctic shelf, the Skolkovo Institute of Science and Technology’s (Skoltech) press service said. Results of the studies are published on Geosciences magazine’s website.
Methane is a main greenhouse gas, which affects the global warming. Russian scientists came to "understanding of the mechanism of massive methane release from bottom sediments of the East Siberian Arctic shelf," the article reads. Active releases not only influence the global warming, but also affect carbon balance and cause accidents in the Arctic, a most promising region for hydrocarbon production. This is why President of the Russian Academy of Sciences Alexander Sergeyev named as a priority the problem to study reasons of methane releases on the East-Siberian shelf, the press service said.
"Experts from Skoltech, the Tomsk Polytechnic University and the Academy of Sciences’ Pacific Oceanology Institute saw that one of the reasons for big methane emissions from bottom sediments on the East-Siberian shelf is destabilizing of gas hydrates, which are located on submarine permafrost, when they react with salt solutions (sea water), which migrate into the thawing underwater permafrost," the press service said.
"Gas hydrates are crystalline clathrate compounds that are formed from gas (mainly methane in natural conditions) and water under certain temperature and pressure conditions," the Russian scientists said in the article. "An important characteristic of gas hydrates is a huge accumulation of gas in the clathrate structure-up to 160 volumes of gas in one volume of hydrate."
Tick tock.