For instance, the forty-one scientists writing in Nature emphasized that, “despite the massive amount of carbon in permafrost soils, emissions from these soils are unlikely to overshadow those from the burning of fossil fuels, which will continue to be the main source of climate forcing.”
Comments like that should make people think twice about proposals to geo-engineer a cooling effect in the Arctic, such as one recently presented at the American Geophysical Union and described in an article at New Scientist.
How problematic methane (and carbon dioxide) from Arctic permafrost will be remains a mystery. A useful 2010 overview in the journal Science, titled “How Stable Is the Methane Cycle?”, emphasized the importance of resolving lingering uncertainties. Thankfully, researchers are on the case, according to a December 19 article in Nature, which highlighted the fact “permafrost science is heating up in the United States.”
As scientists continue to work out the complex physical and chemical processes playing out in the Arctic, it will be incumbent upon journalists to convey important nuances about both terrestrial and oceanic methane, and how both fit into the larger picture of Earth’s changing climate.
I found the comments after Justin Gilles' piece interesting. e.g. John U. Harkness said:
I didn't notice the increases at first - until I set the timespan to 2010-2011. Provisional data show there is a substantial increase in methane levels in the past few months. Looks worrying to me - Barrow seems to be the nearest station to the East Siberian Arctic Shelf, from where seabed methane may be being released.
Do read the rest of John Harkness' comment. He has other interesting points. But who will take him seriously? He doesn't seem to be a mainline climate scientist. He is possibly just someone that cares and takes the time to find out.
It's a pity that Justin Gilles did not address these points. The interesting question is why they were missed. Is it a case of waiting until some paper with a theoretical framework (or a computer model) has been peer reviewed and published?
As one leading empirical climate scientist said this to me recently:
Help!
#1 Posted by Geoff Beacon, CJR on Thu 22 Dec 2011 at 05:05 PM
"Both reporters referred to methane and carbon dioxide being “trapped” in Arctic permafrost, but that’s not quite accurate (Borenstein explained this in the bottom half of his piece; Walsh didn’t). What’s trapped in the permafrost—on land, at least—is organic carbon in the form of ancient, frozen plant and animal matter."
It is in fact accurate. There are 4 sources of CH4 in the Arctic, namely:
Yedoma – thaw of Pleistocene ice av. 2% CH4
Clathrate – thaw of methane filled ice lattice
Bacterial – resumption of biota decay
Gaseous – contained sub-surface in sediments by permafrost capping.
Yedoma is a Pleistocene permafrost containing 2-3% carbon by mass which is estimated to cover over 1 million square kilometers of Siberia. The area is becoming increasingly threatened by rising temperature which has the capacity to thaw yedoma in summer, particularly deposits near the surface. This will releasing CH4 directly into the atmosphere where it oxidizes over an 8-12 year period.
Bacterial action on biota (animal and vegetable material) can – and will – resume when surface permafrost thaws permitting seasonal or longer term establishment of an “active” zone. As the atmosphere warms, permafrost retreats and the active zone becomes deeper, permitting bacterial action on biota to resume, resulting in emission of CH4. It is predicted that by 2100, continuous and discontinuous permafrost will have thawed to a depth of 3 metres, enabling increasing bacterial action on the very extensive biota deposits found in Siberia.
#2 Posted by Mike Pope, CJR on Thu 22 Dec 2011 at 06:43 PM
Thanks for the compliments, Geoff. No I am not a scientist, just a concerned citizen.
A caveat on the Barrow readings is that they are preliminary.
One thing that seems to be overlooked here is that there are not only frozen clathrates beneath the sea. These formations cap large, pressurized pools of free methane.
The continuously bubbling and expanding 'torches' and 'plumes' that Semiletov witnessed suggest that the clathrate is in fact melting, and that the process is continuous and self-reinforcing, probably accelerated by sea water pouring down to displace the melted hydrates, thereby further melting what is there. How long would it take for such a process to essentially 'drill' down into ever deeper levels, eventually hitting the large pools of free methane below?
Here's hoping that this is not what is happening and that there is some other, cyclical or self-limiting process going on here.
#3 Posted by John U. Harkness, CJR on Fri 23 Dec 2011 at 02:07 AM
John
Discussion continues on RealClimate.
Sorry I got your middle inittial wrong there.
#4 Posted by Geoff Beacon, CJR on Fri 23 Dec 2011 at 06:59 AM