First off... Melting permafrost and methane release
A changing climate and accelerated warming in polar regions is causing grounds traditionally held in a permafrost state to transition into a sporadically frozen or even fully defrosted state.
Permafrost - The tipping time bomb
As the video above explains this enables the carbon rich organic matter held in the soil to continue its natural decomposition stalled for as long as it remains frozen. When this decomposition place in the absence of oxygen methane is produced. This can happen in big, explosive and very clear releases leaving craters on the landscape (as documented in this article from the Siberian times).
Methane explosion in Siberia
Source: Siberian Times
More commonly however it is an ongoing, discrete and gradual release of methane that is detectable via analysis of air compositions such as displayed in the following product from NOAA clearly showing high emissions from Siberia in this animation of methane levels in August 2007.
Source: Carbon Tracker-CH4 (available here)
The potential risks to permafrost defrosting and the subsequent methane production is undeniably massive if it were to happen on a significant scale. This is due to the enormous store of carbon held in permafrost, thought to be in the region of about 1,700GT.
What continues to be the focus of debate is the chance of a major, rapid methane release occurring from the defrosting of permafrost and hence also, what climatic changes are needed to induce such a change. Some academics have suggested that the chance of a significant permafrost melting soon is quite likely. A paper titled 'Speleothems reveal 500,000 year history of Siberian Permafrost' by Vaks et al. (2013) used dating of "periods of speleothem growth in a north-south transect of caves in Siberia to reconstruct the history of permafrost in past climate states" their resounding conclusion is that "global climates only slightly warmer than today are sufficient to thaw significant regions of permafrost"- a harrowing conclusion if their conclusions are correct and major regions of permafrost are at risk of defrosting. Indeed already, as the video makes out and as Rachold et al. (2007) concluded there is now evidence that "continuous permafrost is actively thawing in many circum‐Arctic regions".
Despite lots of doom and gloom suggesting studies showing the modelling impacts methane releases from permafrost melting there still remains a vast uncertainty as to what extent, when and if we are to see dangerous methane releases from to be ex permafrost regions in coming decades:
Source: Isaksen et al., 2011
Conclusion on permafrost; easy to sensationalise but hard really to predict; predictions remain wooly despite the potential risks!
In light of length of this discussion here on the risks of methane from defrosting permafrost regions we'll touch on clathrates next week!
Hope to see you back soon!
Methane flaring in Siberia
References:
Vaks, A., Gutareva, O., Breitenbach, S., Avirmed, E., Mason, A., Thomas, A., Osinzev, A., Kononov, A. and Henderson, G. (2013). Speleothems Reveal 500,000-Year History of Siberian Permafrost. Science, 340(6129), pp.183-186.
Isaksen, I., Gauss, M., Myhre, G., Walter Anthony, K. and Ruppel, C. (2011). Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions. Global Biogeochem. Cycles, 25(2), p.n/a-n/a.
Rachold, V., D. Y. Bolshiyanov, M. N. Grigoriev, H.‐W. Hubberten, R. Junker, V. V. Kunitsky, F. Merker, P. Overduin, and W. Schneider (2007), Nearshore Arctic subsea permafrost in transition, Eos Trans. AGU, 88(13), doi:10.1029/2007EO130001.
O'Connor, F., Boucher, O., Gedney, N., Jones, C., Folberth, G., Coppell, R., Friedlingstein, P., Collins, W., Chappellaz, J., Ridley, J. and Johnson, C. (2010). Possible role of wetlands, permafrost, and methane hydrates in the methane cycle under future climate change: A review. Rev. Geophys., 48(4).
Höglund-Isaksson, L.: Global anthropogenic methane emissions 2005–2030: technical mitigation potentials and costs, Atmos. Chem. Phys., 12, 9079-9096, doi:10.5194/acp-12-9079-2012, 2012.
Great post Rob! I find it quite worrying how we are perhaps so focused on the human-produced GHG that the magnitude of warming that could be produced by the release of natural stores is often under-appreciated! You may have covered this in another post - but I presume with greater aridity in the tropical regions, wetland production will decline - will this be counteracted by the permafrost release or will it cause a net increase and further warming?
ReplyDeleteYou're right Laurence, natural tipping points definitely, I feel, be the a real focus of study in coming years... They are already of course but broadly speaking the whole idea of tipping points with methane was only first coined at the very earliest about 15 years ago so knowledge in the field is still lacking in some areas.
ReplyDeleteIt's a tricky one to tell with wetlands; we might see the drying of wetlands as you say in some of the more arid locations around the world if climate in these locations becomes even more arid but we may also see the formation of new wetlands in regions previously too cold to support wetlands - such as in countries like Russia, Siberia, Canada and so forth where soils would previously have been frozen throughout the year. We will also inevitably see the creation of new wetlands around the world as rising sea levels bring new areas within tidal reaches. Overall then I think the chances of a balance are sadly quite unlikely - the more likely scenario may well be greater emission of methane from wetlands around the world.
Having done quite a lot of reading around the melting permafrost in the Arctic i couldn't agree more! The positive feedback system created by melting permafrost in this region is simply intensifying the warming occurring in the Arctic! In the Arctic region will the release of methane be a localized issue or could it have an influence on a global scale?
ReplyDeleteDespite being a 'lighter than air' gas suggesting it will naturally dissipate with time and climatic patterns there is evidence of concentration build ups in some places where emissions are taking place. (A US example is available here: http://www.cortezjournal.com/article/20150419/NEWS01/150419840/NASA-NOAA-take-part-in-methane-study)
ReplyDeleteA large methane release taking place in the arctic could cause rapid localised warming if it is resident at surface level for long enough. This is a real worry considering the accelerated warming taking place already in the Arctic and the positive-feedback implications for further methane releases if it were to remain resident for long enough to cause significant warming...