Ice sheets may be hiding vast reservoirs of methane

[prokaryotes]

A new study indicates that under the frigid weight of Barents Sea Ice sheet, which covered northern Eurasia some 22 000 years ago, significant amounts of methane may have been stored as hydrates in the ground. As the ice sheet retreated, the methane rich hydrates melted, releasing the climate gas into the ocean and atmosphere for millennia.
This finding was published in January 2016 in Nature Communications, publication “Ice-sheet-driven methane storage and release in the Arctic”

If the same process of methane storage is occurring under the current ice sheets, there may be a new threat to take into the account when we are discussing ice sheet retreat in the future. (Source + video)

Also consider this suggestion by Bill McGuire

My concern, however, is that there may be a threat of submarine landslides around the margins of Greenland, which are less well explored. Greenland is already uplifting, reducing the pressure on the crust beneath and also on submarine methane hydrates in the sediment around its margins, and increased seismic activity may be apparent within decades as active faults beneath the ice sheet are unloaded. This could provide the potential for the earthquake or methane hydrate destabilisation of submarine sediment, leading to the formation of submarine slides and, perhaps, tsunamis in the North Atlantic. (Source)

Your thoughts?

[AbruptSLR]

I think that this could be a real issue for Greenland after 2100, and I think that it may very likely be a real issue for the West Antarctic Ice Sheet, WAIS, a few decades after 2050 (the Antarctic folder has discussion on this topic).

[prokaryotes]

Related

Published Monday in the journal Nature Climate Change, the research shows that tiny microbes trapped in Greenland’s permafrost are becoming active as the climate warms and the permafrost begins to thaw. As those microbes become active, they are feeding on previously-frozen organic matter, producing heat, and threatening to thaw the permafrost even further.

http://thinkprogress.org/climate/2015/04/08/3643953/greenland-permafrost-thaw-microbes/

Molecular and biogeochemical evidence for methane cycling beneath the western margin of the Greenland Ice Sheet (2014)

A 2014 study found based on subglacial drainage samples (dominated by Proteobacteria), evidence for methane cycling below the ice sheet of the Russell Glacier. During the study, on 12 July 2012 the most widespread surface melt on record for the past 120 years was observed in Greenland, unfrozen water was present on almost the entire ice sheet surface (98.6%). The findings indicate that methanotrophs could serve as a biological methane sink in the subglacial ecosystem, and the region was at least during the sample time, a source of atmospheric methane. Scaled dissolved methane flux during the 4 months of the summer melt season was estimated at 990 Mg CH4. Because the Russell-Leverett Glacier is representative of similar Greenland outlet glaciers, the researchers concluded that the Greenland Ice Sheet may represent a significant global methane source.

http://www.nature.com/ismej/journal/v8/n11/full/ismej201459a.html

[nukefix]

Is there evidence that this methane has been released during previous interglacials?

[prokaryotes]

Is there evidence that this methane has been released during previous interglacials?

To me this seems very plausible, based on the study linked above on methane cycling under ice sheets, and the new one on pockmarks. The bottom of ice sheets appears to be a perfect place for methanogenesis. This also suggests that ice sheets play a critical role in atmospheric CO2 draw down.