scholarly journals Seismogenic-Triggering Mechanism of Gas Emission Activizations on the Arctic Shelf and Associated Phases of Abrupt Warming

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 428
Author(s):  
Leopold Lobkovsky
Keyword(s):  
Subduction Zone ◽  
Climate Warming ◽  
Gas Hydrates ◽  
Time Lag ◽  
Arctic Shelf ◽  
The Arctic ◽  
Aleutian Island ◽  
Trigger Mechanism ◽  
Methane Release ◽  
Great Earthquakes

A seismogenic trigger mechanism is proposed to explain the abrupt climate warming phases in the Arctic as a result of strong mechanical disturbances in the marginal region of the Arctic lithosphere. Those disturbances might have been caused by great earthquakes in the Aleutian subduction zone, and slowly propagated across the Arctic shelf and adjacent regions, triggering the methane release from permafrost and metastable gas hydrates, followed by greenhouse gas emissions into the atmosphere. The proposed mechanism is based on the identified correlation between the series of the great earthquakes in the Aleutian island arc, which occurred in the early and middle of the 20th century, and the two phases of sharp climate warming, which began in 1920 and 1980. There is a 20-year time lag between these events, which is explained by the time of arrival of deformation waves in the lithosphere (propagating with a velocity of about 100 km per year) at the Arctic shelf and adjacent land from the Aleutian subduction zone, the region of their generation. The trigger mechanism causing the methane release from permafrost and metastable gas hydrates is related to the destruction of micro-sized ice films covering gas hydrate particles, the elements highly important for hydrate self-preservation, as well as destruction of gas-saturated micropores in permafrost rocks due to the slight additional stresses associated with deformation waves, and thus emergence of conditions favorable for gas filtration and its subsequent emission.

scholarly journals Role of Salt Migration in Destabilization of Intra Permafrost Hydrates in the Arctic Shelf: Experimental Modeling

Geosciences ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 188 ◽  
Author(s):  
Evgeny Chuvilin ◽  
Valentina Ekimova ◽  
Boris Bukhanov ◽  
Sergey Grebenkin ◽  
Natalia Shakhova ◽  
...  
Keyword(s):  
Gas Hydrates ◽  
Methane Emission ◽  
Gas Hydrate ◽  
Negative Temperature ◽  
Arctic Shelf ◽  
The Arctic ◽  
Permafrost Degradation ◽  
Stability Zone ◽  
Local Pressure ◽  
Hydrate Stability

Destabilization of intrapermafrost gas hydrate is one possible reason for methane emission on the Arctic shelf. The formation of these intrapermafrost gas hydrates could occur almost simultaneously with the permafrost sediments due to the occurrence of a hydrate stability zone after sea regression and the subsequent deep cooling and freezing of sediments. The top of the gas hydrate stability zone could exist not only at depths of 200–250 m, but also higher due to local pressure increase in gas-saturated horizons during freezing. Formed at a shallow depth, intrapermafrost gas hydrates could later be preserved and transform into a metastable (relict) state. Under the conditions of submarine permafrost degradation, exactly relict hydrates located above the modern gas hydrate stability zone will, first of all, be involved in the decomposition process caused by negative temperature rising, permafrost thawing, and sediment salinity increasing. That’s why special experiments were conducted on the interaction of frozen sandy sediments containing relict methane hydrates with salt solutions of different concentrations at negative temperatures to assess the conditions of intrapermafrost gas hydrates dissociation. Experiments showed that the migration of salts into frozen hydrate-containing sediments activates the decomposition of pore gas hydrates and increase the methane emission. These results allowed for an understanding of the mechanism of massive methane release from bottom sediments of the East Siberian Arctic shelf.

scholarly journals Postglacial response of Arctic Ocean gas hydrates to climatic amelioration

2017 ◽  
Vol 114 (24) ◽  
pp. 6215-6220 ◽  
Author(s):  
Pavel Serov ◽  
Sunil Vadakkepuliyambatta ◽  
Jürgen Mienert ◽  
Henry Patton ◽  
Alexey Portnov ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Gas Hydrates ◽  
Gas Hydrate ◽  
Bottom Water ◽  
Environmental Changes ◽  
Thermal Dissociation ◽  
Ice Sheet ◽  
The Arctic ◽  
Ocean Bottom ◽  
Methane Release

Seafloor methane release due to the thermal dissociation of gas hydrates is pervasive across the continental margins of the Arctic Ocean. Furthermore, there is increasing awareness that shallow hydrate-related methane seeps have appeared due to enhanced warming of Arctic Ocean bottom water during the last century. Although it has been argued that a gas hydrate gun could trigger abrupt climate change, the processes and rates of subsurface/atmospheric natural gas exchange remain uncertain. Here we investigate the dynamics between gas hydrate stability and environmental changes from the height of the last glaciation through to the present day. Using geophysical observations from offshore Svalbard to constrain a coupled ice sheet/gas hydrate model, we identify distinct phases of subglacial methane sequestration and subsequent release on ice sheet retreat that led to the formation of a suite of seafloor domes. Reconstructing the evolution of this dome field, we find that incursions of warm Atlantic bottom water forced rapid gas hydrate dissociation and enhanced methane emissions during the penultimate Heinrich event, the Bølling and Allerød interstadials, and the Holocene optimum. Our results highlight the complex interplay between the cryosphere, geosphere, and atmosphere over the last 30,000 y that led to extensive changes in subseafloor carbon storage that forced distinct episodes of methane release due to natural climate variability well before recent anthropogenic warming.

scholarly journals Optimal method of Arctic hydrocarbons production-and-supply system implementation

2021 ◽  
Vol 266 ◽  
pp. 01008
Author(s):  
D.S. Bratskikh ◽  
A.M. Schipachev ◽  
V.A. Bukov
Keyword(s):  
Natural Gas ◽  
Gas Hydrates ◽  
Barents Sea ◽  
Arctic Shelf ◽  
Hydraulic Calculation ◽  
The Arctic ◽  
Optimal Method ◽  
Subsequent Formation ◽  
Advantages And Disadvantages ◽  
The Barents Sea

One of the most important issues in the development of the Arctic shelf is the rationality of transportation. Selection of the optimal method is an integral part of the project, in the framework of which this article is written. Earlier all possible methods and their advantages and disadvantages were evaluated. Within the framework of this article, t optimal method for the development of reserves on the Arctic shelf will be proposed, taking into account the possibilities of development and the effectiveness of subsequent transportation to the importing countries. The risks of gas hydrates were considered. The prospects of development of the Northern Sea Route between Russia and Asian countries are assessed; the cost of transportation of liquefied natural gas and compressed natural gas from the Barents Sea to Central Europe is compared. The hydraulic calculation of the selected section of the gas pipeline network is conducted. The economic calculation of the project as a whole is accomplished. The optimal location of the route in relation to the reserves in the Barents Sea has been chosen. Pressure losses in the selected zone were no more than 12.24 MPa with pipeline pressure from 8 to 16 MPa. In this case, condensation and subsequent formation of gas hydrates are not possible. Using only three sections of the network, the profit of the project will be 223 billion rubles per year. In accordance with this the best way of hydrocarbons realization in the Arctic is a combined method of transportation with modern methods of extraction and pipelaying laying.

scholarly journals Role of Warming in Destabilization of Intrapermafrost Gas Hydrates in the Arctic Shelf: Experimental Modeling

Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 407 ◽  
Author(s):  
Chuvilin ◽  
Davletshina ◽  
Ekimova ◽  
Bukhanov ◽  
Shakhova ◽  
...  
Keyword(s):  
Gas Hydrates ◽  
Methane Emission ◽  
Gas Hydrate ◽  
Arctic Shelf ◽  
The Arctic ◽  
Effect Of Temperature ◽  
Permafrost Degradation ◽  
Local Pressure ◽  
Hydrate Dissociation ◽  
Hydrate Stability

Destabilization of intrapermafrost gas hydrates is one of the possible mechanisms responsible for methane emission in the Arctic shelf. Intrapermafrost gas hydrates may be coeval to permafrost: they originated during regression and subsequent cooling and freezing of sediments, which created favorable conditions for hydrate stability. Local pressure increase in freezing gas-saturated sediments maintained gas hydrate stability from depths of 200–250 meters or shallower. The gas hydrates that formed within shallow permafrost have survived till present in the metastable (relict) state. The metastable gas hydrates located above the present stability zone may dissociate in the case of permafrost degradation as it becomes warmer and more saline. The effect of temperature increase on frozen sand and silt containing metastable pore methane hydrate is studied experimentally to reconstruct the conditions for intrapermafrost gas hydrate dissociation. The experiments show that the dissociation process in hydrate-bearing frozen sediments exposed to warming begins and ends before the onset of pore ice melting. The critical temperature sufficient for gas hydrate dissociation varies from −3.0 to −0.3 °C and depends on lithology (particle size) and salinity of the host frozen sediments. Taking into account an almost gradientless temperature distribution during degradation of subsea permafrost, even minor temperature increases can be expected to trigger large-scale dissociation of intrapermafrost hydrates. The ensuing active methane emission from the Arctic shelf sediments poses risks of geohazard and negative environmental impacts.

РRINCIPLES OF ONSHORE FACILITIES DESIGN FOR THE OBJECTS OF OIL AND GAS COMPLEX IN THE ARCTIC SHELF

2018 ◽  
pp. 62-68
Author(s):  
M.A. Magomedgadzhieva ◽  
◽  
G.S. Oganov ◽  
I.B. Mitrofanov ◽  
A.M. Karpov ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Arctic Shelf ◽  
The Arctic ◽  
Facilities Design

scholarly journals CAS FGOALS-f3-L Large-ensemble Simulations for the CMIP6 Polar Amplification Model Intercomparison Project

2021 ◽  
Author(s):  
Bian He ◽  
Xiaoqi Zhang ◽  
Anmin Duan ◽  
Qing Bao ◽  
Yimin Liu ◽  
...  
Keyword(s):  
Time Lag ◽  
The Arctic ◽  
Global Ocean ◽  
Arctic Amplification ◽  
Model Intercomparison ◽  
Large Ensemble ◽  
Sea Ice Concentration ◽  
Ensemble Simulations ◽  
Polar Amplification ◽  
Intercomparison Project

AbstractLarge-ensemble simulations of the atmosphere-only time-slice experiments for the Polar Amplification Model Intercomparison Project (PAMIP) were carried out by the model group of the Chinese Academy of Sciences (CAS) Flexible Global Ocean-Atmosphere-Land System (FGOALS-f3-L). Eight groups of experiments forced by different combinations of the sea surface temperature (SST) and sea ice concentration (SIC) for pre-industrial, present-day, and future conditions were performed and published. The time-lag method was used to generate the 100 ensemble members, with each member integrating from 1 April 2000 to 30 June 2001 and the first two months as the spin-up period. The basic model responses of the surface air temperature (SAT) and precipitation were documented. The results indicate that Arctic amplification is mainly caused by Arctic SIC forcing changes. The SAT responses to the Arctic SIC decrease alone show an obvious increase over high latitudes, which is similar to the results from the combined forcing of SST and SIC. However, the change in global precipitation is dominated by the changes in the global SST rather than SIC, partly because tropical precipitation is mainly driven by local SST changes. The uncertainty of the model responses was also investigated through the analysis of the large-ensemble members. The relative roles of SST and SIC, together with their combined influence on Arctic amplification, are also discussed. All of these model datasets will contribute to PAMIP multi-model analysis and improve the understanding of polar amplification.

Sign in / Sign up

Export Citation Format

Share Document