Uncertainty in temperature and sea level datasets for the Pleistocene glacial cycles: Implications for thermal state of the subsea sediments

Malakhova, Valentina V.; Елисеев, А. В.

doi:10.1016/j.gloplacha.2020.103249

Cited by 18 publications

(26 citation statements)

References 46 publications

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“…We construct paletemperature curves for different isobaths and regions based on the shelf zoning in terms of bathymetry, tectonic structures, and geological development [10,11,54]. This method based on transformation of the isotope curve of Vostok station (East Antarctic), was widely used earlier [6,9,16] and is being used in a modified form now [19,23,25].…”

Section: Methods For Generating a Scenario Of Geological Development mentioning

confidence: 99%

“…To calculate the thermal state of permafrost and thermobaric conditions for gas hydrates, we use a one-dimensional model of thermal processes in bottom sediments taking into account the phase transitions between frozen and thawed ground [18,19].…”

Section: Description Of the Numerical Modelmentioning

confidence: 99%

“…Later in the research performed by V.V. Malakhova [17][18][19], the approaches were developed and the evolution and current state of permafrost and the GHSZ of the Eastern Siberia shelf were under modeling.…”

Section: Introductionmentioning

confidence: 99%

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Permafrost and Gas Hydrate Stability Zone of the Glacial Part of the East-Siberian Shelf

et al. 2020

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By using thermal mathematical modeling for the time range of 200–0 thousand years ago, the authors have been studying the role the glaciation, covered the De Long Islands and partly the Anjou Islands at the end of Middle Neopleistocene, played in the formation of permafrost and gas hydrates stability zone. For the modeling purpose, we used actual geological borehole cross-sections from the New Siberia Island. The modeling was conducted at geothermal flux densities of 50, 60, and 75 mW/m2 for glacial and extraglacial conditions. Based on the modeling results, the glaciated area is characterized by permafrost thickness of 150–200 m lower than under extraglacial conditions. The lower boundary of the gas hydrate stability zone in the glacial area at 50–60 mW/m2 is located 300 m higher than the same under extraglacial conditions. At 75 mW/m2 in the area of 20–40 m isobaths, open taliks are formed, and the gas hydrate stability zone was destroyed in the middle of the Holocene. The specified conditions and events were being formed in the course of the historical development of the glacial area with a predominance of the marine conditions peculiar to it from the middle of the Middle Neopleistocene.

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Section: Methods For Generating a Scenario Of Geological Development mentioning

confidence: 99%

Section: Description Of the Numerical Modelmentioning

confidence: 99%

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Permafrost and Gas Hydrate Stability Zone of the Glacial Part of the East-Siberian Shelf

et al. 2020

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“…All these projections except that by Majorowicz et al (2012) neglect future changes in parameters of the Earth orbit which evolution might initiate new glacial inception. It was simulated earlier that both the subsea permafrost and PAHM MHSZ were markedly thinner or even non-existent at the middle and outer parts of the Arctic shelf aftermath the Pleistocene glacial terminations (Romanovskii et al, 2005(Romanovskii et al, , 2006Majorowicz et al, 2012;Malakhova and Eliseev, 2017, 2020aGavrilov et al, 2020). This inception, in turn, may be delayed because of the ongoing, mostly CO 2 -induced climate warming (Archer and Ganopolski, 2005;Ganopolski et al, 2016).…”

Section: Introductionmentioning

confidence: 97%

Subsea permafrost and associated methane hydrates: how long will they survive in the future?

Malakhova

Елисеев

2022

Preprint

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Abstract. We performed simulations with SMILES (the Sediment Model Invented for Long-tErm Simulations) for 100 kyr in future forced by the output of an Earth System model with internally calculated ice sheets. This Earth System model was driven by idealised scenarios of CO2 emissions (applied at time instant t = 0 loosely corresponding to common era year 1950) and by changes of the parameters of the Earth orbit. The simulations are carried out with different values of the heat flux from the Earth interior. We neglected possible impact of hydrostatic pressure changes due to future sea level changes on freeze/thaw temperature and on thermodynamic stability of methane hydrates. We found that at the outer shelf permafrost disappears either before t = 0 or during few centuries in future. In contrast, for the middle and shallow parts of the shelf, in the CO2-emission forced runs the subsea permafrost survives, at least, for 5 kyr after the emission onset or even for much longer. Without an applied greenhouse forcing permafrost exists here at least until 22 kyr after the CO2 emission onset or even survives till the end of the model runs. At the same parts of the shelf, methane hydrate stability zone disappears not earlier that at t = 3 kyr after the CO2 emission onset, but, typically, it survives until 11 to 41 kyr after this onset. Time instants of local extinction of both the subsea permafrost and methane hydrates stability zone (MHSZ) are negatively correlated with the geothermal heat flux because of both permafrost thaw and MHSZ shrinking basically occurs from bottom. However, thaw from the top and the deepening of the MHSZ table is basically determined by the applied CO2 forcing scenario; this is more important for the permafrost than for MHSZ. In general, the CO2-induced warming in our simulations is able to enhance the pan-Arctic subsea permafrost loss severalfold during 1 kyr after the emissions onset, but is less instrumental for the respective MHSZ loss.

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“…Glacial cycles led to periods of transgressions and regressions of the seas of the Arctic Ocean during the Pleistocene. Continental permafrost was formed on the Arctic shelf during periods of sea regression when the shelf became dry land [12,17,18]. During the subsequent rise in sea level, such permafrost found itself underwater.…”

Section: Introductionmentioning

confidence: 99%

Model Study of the Effects of Climate Change on the Methane Emissions on the Arctic Shelves

Malakhova

Golubeva

2022

Atmosphere

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Based on a regional ice-ocean model, we simulated the state of the water masses of the Arctic Ocean to analyze the transport of dissolved methane on the Arctic shelves. From 1970 to 2019, we obtained estimates of methane emissions at the Arctic seas due to the degradation of submarine permafrost and gas release at the ocean–bottom interface. The calculated annual methane flux from the Arctic shelf seas into the atmosphere did not exceed 2 Tg CH4 yr−1. We have shown that the East Siberian shelf seas make the main contribution to the total methane emissions of the region. The spatial variability of the methane fluxes into the atmosphere is primarily due to the peculiarities of the water circulation and ice conditions. Only 7% of the dissolved methane originating from sediment enters the atmosphere within the study area. Most of it appears to be transported below the surface and oxidized by microbial activity. We found that increasing periods and areas of ice-free water and decreasing ice concentration have contributed to a steady increase in methane emissions since the middle of the first decade of the current century.

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Uncertainty in temperature and sea level datasets for the Pleistocene glacial cycles: Implications for thermal state of the subsea sediments

Cited by 18 publications

References 46 publications

Permafrost and Gas Hydrate Stability Zone of the Glacial Part of the East-Siberian Shelf

Permafrost and Gas Hydrate Stability Zone of the Glacial Part of the East-Siberian Shelf

Subsea permafrost and associated methane hydrates: how long will they survive in the future?

Model Study of the Effects of Climate Change on the Methane Emissions on the Arctic Shelves

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