Electronic translation from the Russian
Tomsk University scientists : under-water permafrost on the East Siberian Arctic shelf is deteriorating faster than previously thought
Ученые ТПУ: подводная мерзлота на Восточно-Сибирском арктическом шельфе деградирует быстрее, чем считалось ранее
9 August, 2017
The rate of vertical degradation of under-water permafrost on the East Siberian Arctic shelf over the last 30 years, is reaching 18 cm per year (on average, 14 cm per year), which is much higher than previously thought.
The results, obtained from the large-scale study of the state of underwater permafrost throughout the entire history of research in the Russian Arctic, but the Arctic as a whole, have been shared by scientists of Tomsk Polytechnic University in a scientific paper published in the journal Nature Communications.
Photo: Arctic expedition of Russian and Swedish scientists SWERUS-C3
In July, scientists TPU published a scientific article in the journal Nature Communications (IF 12,1; Q1).
Sponsored polytechnics were scientists from Russia and Sweden.
According to scientists, previously it was thought that the main part of the submarine permafrost of the shelf seas of the Eastern Arctic (MVA) — the wide and shallow shelf of the World ocean is continuous, which excludes the possibility of destabilization digitalguy giant pool of methane hydrates. According to the model estimates of the intergovernmental panel of climate change (Intergovernmental Panel on Climate Change, IPCC), it is assumed that before the end of the 21st century, the degradation of submarine permafrost in the Eastern Arctic seas may not exceed several meters, and for the formation of through taliks (zones of degradation — the complete thawing of the underwater permafrost) will require hundreds, if not thousands of years, which eliminates the possibility of a massive release of methane (CH4) is the second most important greenhouse gas — from seabed sediments MVA in the water column-atmosphere due to the destruction of hydrates. Based on these conclusions, based on simulation without well-founded formulation of boundary and initial conditions and no validation by field data obtained by scientists of TPU in cooperation with the leading scientists of the Siberian Arctic consortium, created on a scientific platform, TPU, potential climatic role of the offshore MBA in the context of the possibility of a massive release of methane into the water column-atmosphere IPCC is regarded as insignificant and excluded from consideration. The article shows that this is not so.
On the basis of re-drilling four wells, made by the permafrost Institute SB RAS in 1982-1983, scientists have shown that the vertical velocity of the degradation of submarine permafrost in the last 30 years reach 18 cm per year (mean 14 cm per year), which is approximately an order of magnitude higher than was previously assumed.
"Progressive degradation (thawing) of underwater permafrost leads to the formation of gazovikami channels, the presence of which was predicted on the basis of our first results in MBA in 2000-2010, and mathematical modeling, — says the first author, Professor, Department of Geology and mineral exploration TPU Natalia Shakhova. — On the basis of new results obtained by means of complex biogeochemical, geophysical, and geological studies carried out in 2011-2016 years, we come to the conclusion that in some parts of the East Siberian shelf, the roof of the submarine permafrost has already reached the depth of the zone of stability of hydrates, the destruction of which may lead to a massive bubble of methane emissions. Such phenomena have been discovered and documented, our team of authors for many years on the shallow and deep shelf of the MVA. And the proof of the existence of the upward movement of the gas front through the thick rain with a speed of five metres per year can also serve as a confirmation of our hypothesis about the destabilization of hydrates as the main candidate to explain the anomalously high concentrations of methane in water and air on the East Siberian shelf, which was published in 2010 in the journal Science. According to our results, published in Nature Geoscience, Science and Philosophical Transactions, Royal Society, the magnitude of bubble flux of CH4 from sediments to water in an MBA can vary from milligrams to hundreds of grams per square meter per day, depending on the state of underwater permafrost, which leads to an increase in the concentration of atmospheric CH4 in the near-water layer up to values 2-4 times higher than the background concentration measured on our planet".
Natalia Shakhova notes that these results have been confirmed in the expedition, organized and executed in a MVA in 2016, together with scientists from the Pacific Oceanological Institute Feb RAS (POI), with the participation of the Institute of Oceanology, RAS (ioras) and the Institute of atmospheric physics RAS (IAP RAS); relevant publications are expected in 2018.
"In addition, together with scientists from ioras us a new mechanism of acceleration of methane bubble release from the bottom sediments into the water (and into the atmosphere) due to the ice vypaivanija the stamukha in shallow water, and the icebergs on the outer shelf of the MVA, resulting in formation of a furrow, reaching the gas front.
The size of these furrows reach many kilometers, at a depth of vypaivanija to 4-6 meters, which in many places is accompanied by bubble emissions of CH4 in the water column-atmosphere", — says the head of the International laboratory for the study of carbon in Arctic seas, TPU, corresponding member of RAS Igor Semiletov.
As noted, in turn, Natalia Shakhova implementation of recently adopted by the Russian Government plan of actions for implementation of the development Strategy of the Arctic zone of the Russian Federation and national security for the period up to 2020 is largely dependent on understanding the processes and factors that can help or hinder the progressive development of the Arctic region.
"Currently, the level of this understanding is mainly provided by hydro-meteorological research. However, without regard to their connection with the complex biogeochemical and geological processes occurring as a result of the degradation of submarine and coastal permafrost, as shown in work published in Nature Communications, it is impossible to assess the risks arising from the development of the Arctic shelf", says Natalia Shakhova.
For example, for safe drilling of the resource need to have knowledge on the situation, structure and condition of submerged permafrost, the places potentially dangerous in the context of a possible massive and even catastrophic release of methane due to an explosion of hydrates (such cases are known in the Pechora sea, the Gulf of Mexico, the Straits of Dmitri Laptev to the East Siberian sea). In this context, it is crucial to continue a comprehensive study TPU scientists with colleagues from leading institutions and universities of Russia and other countries. To raise the technological level of works on the study of the state of underwater permafrost and Arctic shelf of Russia, the implementation of which in 2018 is scheduled expedition, the scientists find it expedient to modify the latest version of the submersible TPU, which has been tested in expeditions to the seas of the Eastern Arctic in 2016.
"The results of our study provide fundamentally new knowledge about the mechanism of the processes responsible for changing the state of underwater permafrost on the East Siberian shelf, which according to various estimates accounts for up to 80 % or more of an entire submarine permafrost of the Northern hemisphere, under which there are huge reserves of hydrocarbons in the form of hydrates, oil-free gas.
In the future, based on these data will be reviewed and revised approaches to the study of the state of underwater permafrost and its mathematical modeling, which is extremely important to reduce geohazard arising from the conduct of exploratory and production drilling. However, there still remain many unresolved questions that will be addressed by future research our research team," concludes Igor Semiletov.