Risks for the future 2: Methane Hydrates

Methane Clathrates: the scare factor

Over the last decade there have been several publications citing methane hydrates(also known by methane clathrates) as being cause of utmost concern in the coming century, having even been nicknamed as the source of 'artic methane apocalypse or 'arctic methane catastrophe'. The Arctic Methane Emergency Group are certainly gravely concerned (http://ameg.me for more), the following taken from a summary of reasons for action needing to be taken immediately:

Source: Arctic Methane Emergency Group

There are clearly many big claims here, the last though has been the subject of intense debate over the past few years - the suggestion that 'a 50 gigaton methane burst is possible at any time'. 

(Source: Authors own)

As the figure above highlights - this really is a release of enormous scale and if it were to happen on anything but a multi century-scale timeframe would certainly have very major consequences for humanity. So, what are the chances of this happening and where does the figure of 50Gt come from?

Plume of methane from methane hydrates being emitted from ocean floor

Source: Ruppel (2011)

Well... It originally appeared in a short paper by Shakova et al. published in 2008 (full paper available here). Since then there has been intense to-ing and fro-ing in the scientific community with various skeptic groups trying to outprove the other as to the likelihood of a 50Gt release in particular, but also the chances of any significant release this century. If you're interested in learning more about this a summary article published by the Guardian is available here.

At present, I would conclude it remains hard to nail down a genuinely substantiable statistic as to the likelihood of a methane burst from stored hydrates. The conclusion by the IPCC in 2013 that:

Source: Carbon and Other Biogeochemical Cycles in IPCC AR5, 2013

Appears true today also - I struggled to find any new evidence since 2013 substantiating the likelihood of the burst any more solidly than prior to 2013. An article in the New Scientist (23 May 2015: p38-41) came to the same conclusion with their investigation which coined their front-cover headline "It's not grim up north - arctic safe from methane apocalypse" along with the concluding statement 

"There is, then, no solid evidence to back the idea of a methane bomb and past climate records suggest there is no cause for alarm."

For the sake of the planet and of mankind let's hope Anil Ananthaswamy from New Scientist is right on this one and that conclusions like hers and like Ruppel's (2011) are indeed correct; 

"Catastrophic, widespread dissociation of methane gas hydrates will not be triggered by continued climate warming at contemporary rates (0.2ºC per decade; IPCC 2007) over timescales of a few hundred years."

References:

Ananthaswamy, A. (2015). The methane apocalypse. New Scientist, pp.38-41.

Ciais, P., C. Sabine, G. Bala, L. Bopp, V. Brovkin, J. Canadell, A. Chhabra, R. DeFries, J. Galloway, M. Heimann, C. Jones, C. Le Quéré, R.B. Myneni, S. Piao and P. Thornton, 2013: Carbon and Other Biogeochemical Cycles. In: Cli- mate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 

Ruppel, C. D. (2011) Methane Hydrates and Contemporary Climate Change. Nature Education Knowledge 3(10):29