Dr. Methane Gun, Or, How I Learned to Stop Worrying and Love Extinction

April 26, 2011

In viewing climate change, every so often there comes along some aspect of that horror-in-coming that’s even more morbid, more dark-cast depressing than normal, and one of those is the impact of methane gas deposits blasting out of the Arctic permafrost (or permamelt, ha,ha,HA) thawing at an accelerating rate, beyond predictions.

These methane ‘burps’ are nothing new — I’ve posted on the phenomenon before — but this process continues and the terror is this: Underground stores of methane are important because scientists believe their sudden release has in the past been responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species.

(Illustration found here).

Joe Romm at Climate Progress: Methane release from the not-so-perma-frost is the most dangerous amplifying feedback in the entire carbon cycle…Methane (CH4) deserves attention it is such a highly potent greenhouse gas — 25-33 times more powerful than carbon dioxide (CO2) over a 100-year time-horizon, but as much as 100 time more potent over 20 years…
And last year, the National Science Foundation released this:

The research results, published in the March 5 edition of the journal Science, show that the permafrost under the East Siberian Arctic Shelf, long thought to be an impermeable barrier sealing in methane, is perforated and is starting to leak large amounts of methane into the atmosphere.
Release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming.
“The amount of methane currently coming out of the East Siberian Arctic Shelf is comparable to the amount coming out of the entire world’s oceans,” said Shakhova, a researcher at UAF’s International Arctic Research Center.
“Subsea permafrost is losing its ability to be an impermeable cap.”

In a post yesterday, Romm explored a new Geophysical Research Letters study on a long-ago methane eruption and how that’s extremely pertinent right now.
A couple of nuggets:

Methane (CH4) is an extremely potent greenhouse gas, 20-30 times more powerful than carbon dioxide (CO2) on a century timescale.
Fortunately it normally occurs in very low concentration in the atmosphere — about 0.3 to 0.4ppm during glacial periods and 0.6 to 0.7ppm during warmer periods.
In 1750 the concentration was ~0.7ppm.
By 2010 it had reached >1.8ppm, and is now at its highest level in 500,000 years.
This is largely due to human activity, particularly the keeping of large herds of cattle and flocks of chickens and the production of fossil fuels.
Methane has a relatively short life in the atmosphere where it oxidizes into CO2 over a period of 9-15 years.

Very rapid and massive release of carbon deficient in ∂13C, does put one in mind of the Methane Gun hypothesis.
It postulates that methane clathrate at shallow depth begins melting and through the feed-back process accelerate atmospheric and oceanic warming, melting even larger and deeper clathrate deposits.
The result: A relatively sudden massive venting of methane — the firing of the Methane Gun.
Recent discovery by Davy et al (2010) of kilometer-wide (ten 8-11 kilometer and about 1,000 1-kilometer-wide features) eruption craters on the Chatham Rise seafloor off New Zealand adds further ammunition to the Methane Gun hypothesis.

While natural global warming during the ice ages was initiated by increased solar radiation caused by cyclic changes to Earth’s orbital parameters, there is no evident mechanism for correcting Anthropogenic Global Warming over the next several centuries.
The latter has already begun producing methane and CO2 in the Arctic, starting a feedback process which may lead to uncontrollable, very dangerous global warming, akin to that which occurred at the PETM.
This extremis we ignore – to our peril.

Romm adds: It is worth noting that no climate model currently incorporates the amplifying feedback from methane released by a defrosting tundra. Indeed the NSIDC/NOAA study I wrote about in February on methane release by the land-based permafrost itself doesn’t even incorporate the carbon released by the permafrost carbon feedback into its warming model!

So now, Major ‘King’ Kong can instead ride that methane gun into oblivion.

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