%0 Journal Article
%T Arctic Ocean Gas Hydrate Stability in a Changing Climate
%A Michela Giustiniani
%A Umberta Tinivella
%A Martin Jakobsson
%A Michele Rebesco
%J Journal of Geological Research
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/783969
%X Recent estimations suggest that vast amounts of methane are locked in the Arctic Ocean bottom sediments in various forms of gas hydrates. A potential feedback from a continued warming of the Arctic region is therefore the release of methane to the atmosphere. This study addresses the relationship between a warming of the Arctic ocean and gas hydrate stability. We apply a theoretical model that estimates the base of the gas hydrate stability zone in the Arctic Ocean considering different bottom water warming and sea level scenarios. We model the present day conditions adopting two different geothermal gradient values: 30 and 40¡ãC/km. For each geothermal gradient value, we simulate a rise and a decrease in seafloor temperature equal to 2¡ãC and in sea level equal to 10£¿m. The results show that shallow gas hydrates present in water depths less than 500£¿m would be strongly affected by a future rise in seafloor temperature potentially resulting in large amounts of gas released to the water column due to their dissociation. We estimate that the area, where there could be complete gas hydrate dissociation, is about 4% of the area where there are the conditions for gas hydrates stability. 1. Introduction Vast quantities of methane are trapped in oceanic hydrate deposits, and there is a concern that a rise in the ocean temperature will induce dissociation of these hydrate accumulations, potentially releasing large amounts of methane into the atmosphere [1, 2]. In this context, the Arctic should be considered a critical area in a warming climate because massive amounts of methane are currently locked as gas hydrates in ocean sediments and in permafrost that could be released [3¨C6]. Moreover, in the Arctic ocean, the gas hydrate stability zone is especially sensitive to climate change because the degree of temperature change is greater than at lower latitudes [4]. For example, the gas hydrate stability zone along continental slopes is found to be sensitive to even small changes in ocean bottom temperature [4], and the Arctic Ocean most likely has a larger gas hydrate stability zone compared to other oceans because of its cold water and low geothermal gradients [7]. However, it is still unclear whether the recent discoveries of methane emissions in the Arctic shelf and slope region are a result of better mapping and detection methods or whether they reflect a natural variability or environmental conditions following the present climate change. Gas hydrates are solid crystalline compounds, in which gas molecules are lodged within the clathrate crystal lattice [8].
%U http://www.hindawi.com/journals/jgr/2013/783969/