The left panel shows the increase in temperature with depth for sediments, located at 1000 metres water depth, that are exposed to linear bottom-water warming of 1 °C per 1000 years. Only the deepest gas hydrates dissociate, and only after a significant time delay. Methane released in this fashion is likely to migrate to slightly shallower depths and reform gas hydrate. The right panel depicts the response of permafrost-free Arctic upper-slope sediments at 320 metres water depth to a linear increase in bottom-water temperature of 3°C per 100 years. In contrast to the deep marine setting, gas hydrates in shallow settings can be destabilized more rapidly, and dissociation occurs at the upper hydrate surface, facilitating the methane transport away from the hydrate. Temperature profiles were calculated by applying a thermal conductivity of 1.2 W m–1 K–1 and a volumetric thermal capacity of 5.1 J cm–3 K–1.

Year: 2009

From collection: Frozen Heat - A Global Outlook on Methane Gas Hydrates

Cartographer: GRID-Arendal