Wallmann, Klaus , Riedel, Michael , Hong, W. L., Patton, H., Hubbard, A., Pape, T., Hsu, C. W., Schmidt, Christopher , Johnson, J. E., Torres, M. E., Andreassen, K., Berndt, Christian and Bohrmann, Gerhard (2018) Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming. Nature Communications, 9 (Article number: 83 ). DOI 10.1038/s41467-017-02550-9.

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Abstract

Methane seepage from the upper continental slopes of Western Svalbard has previously
been attributed to gas hydrate dissociation induced by anthropogenic warming of ambient
bottom waters. Here we show that sediment cores drilled off Prins Karls Foreland contain
freshwater from dissociating hydrates. However, our modeling indicates that the observed
pore water freshening began around 8 ka BP when the rate of isostatic uplift outpaced
eustatic sea-level rise. The resultant local shallowing and lowering of hydrostatic pressure
forced gas hydrate dissociation and dissolved chloride depletions consistent with our geochemical
analysis. Hence, we propose that hydrate dissociation was triggered by postglacial
isostatic rebound rather than anthropogenic warming. Furthermore, we show that methane
fluxes from dissociating hydrates were considerably smaller than present methane seepage
rates implying that gas hydrates were not a major source of methane to the oceans, but
rather acted as a dynamic seal, regulating methane release from deep geological reservoirs.

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