Abstract
This paper summarizes current understanding of the processes that determine the dynamics of the subsea permafrost–hydrate system existing in the largest, shallowest shelf in the Arctic Ocean; the East Siberian Arctic Shelf (ESAS). We review key environmental factors and mechanisms that determine formation, current dynamics, and thermal state of subsea permafrost, mechanisms of its destabilization, and rates of its thawing; a full section of this paper is devoted to this topic. Another important question regards the possible existence of permafrost-related hydrates at shallow ground depth and in the shallow shelf environment. We review the history of and earlier insights about the topic followed by an extensive review of experimental work to establish the physics of shallow Arctic hydrates. We also provide a principal (simplified) scheme explaining the normal and altered dynamics of the permafrost–hydrate system as glacial–interglacial climate epochs alternate. We also review specific features of methane releases determined by the current state of the subsea-permafrost system and possible future dynamics. This review presents methane results obtained in the ESAS during two periods: 1994–2000 and 2003–2017. A final section is devoted to discussing future work that is required to achieve an improved understanding of the subject.
Highlights
The Arctic is warming dramatically, with potentially catastrophic impacts on climate through rapid mobilization of the labile reservoirs of carbon sequestered in permafrost [1]
The purpose of this paper is to introduce the East Siberian Arctic Shelf (ESAS) permafrost–hydrates system, which is by highlighting the specific processes that determine and control its that dynamics
Based on results of the first comprehensive scientific re-drilling, it was shown that subsea permafrost in the near-shore area of the ESAS has exhibited downward ice-bonded permafrost table (IBPT) movement of ~14 cm y−1 during the last 30 years vs. ~6 cm y−1 in earlier years since inundation [22]
Summary
The Arctic is warming dramatically, with potentially catastrophic impacts on climate through rapid mobilization of the labile reservoirs of carbon sequestered in permafrost [1]. Geosciences 2019, 9, x FOR PEER REVIEW this process creates some of the largest uncertainties in climate research related to Significant reserves of CH4 are held in the Arctic seabed [10], but the release of CH4 to the overlying cryosphere–climate–carbon couplings [7,8,9]. 4 shallow region has recently been shown to be Britain, Italy, and Japan combined) This vast yet Arctic ecosystems [19,20]; but of unlike terrestrial. 4 preserved within the shallow ESAS seabed deposits by 3–5 orders of magnitude, considering the sheer amount of CH4 preserved within the shallow and the documented thawing rates of subsea permafrost reported recently [22]. ESAS seabed deposits and the documented thawing rates of subsea permafrost reported recently paper is to introduce the ESAS permafrost–hydrates system, which is largely unfamiliar to scientists,. Largely unfamiliar to scientists, by highlighting the specific processes determine and control its dynamics
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