Hydrates

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Subcap Methane Feedbacks. Part 3: Methane from beneath the ice

Originally posted at Skeptical Science

The previous two parts (one here and two here) of this series examined the evidence for seeps of geological methane through the cap provided by permafrost and looked at estimates of the magnitude of such seeps in relation to other sources of atmospheric methane. In this section, we will look at the emerging evidence for actual and potential methane releases related to glaciers and ice sheets. The sources of this methane are varied: fossil methane released through reactivated fractures; organic matter once buried and now exhumed; and possible methane hydrates lurking under the big ice sheets.

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Subcap Methane Feedbacks. Part 4: Speculations

Originally posted at Skeptical Science

Previous articles in this series have reviewed recent research on methane sources from beneath permafrost and ice sheets. Part 1 looked at subcap fossil methane seeps in Alaska;Part 2 provided a perspective for the size of these seeps in relation to other natural and human sources; and Part 3 looked at potential methane sources resulting from the withdrawal of glaciers and ice sheet. In this final section, I will try to make estimates of what subcap methane emissions may mean for future climate change; more as a speculative basis for discussion rather than an authoritative prediction. Firstly, though, I will argue for a role for subcap methane emissions on the East Siberian Arctic Shelf (ESAS). 

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