Looking to the future: Emissions predictions

Happy new year to all from a rather sorry looking, thinly snow covered European Alps!

The low snowfall in the European Alps this winter reminds me of a talk I went to a few weeks ago by James Balog (the man behind the 'Extreme Ice Survey' - http://extremeicesurvey.org for more). 

He has done a really fantastic job of linking science and art through his ongoing study of glaciers in some of the world's most mountainous and polar regions. He poingnently described glaciers as 'the canary in the global coal mine' as he showed clips of glacial retreat the world over. One of his clips was from one of Europe's most significant glaciers the 'Mer de Glace' (The Sea of Ice) about 20 miles away from where I am staying at the moment. I remember visiting this glacier as a young boy, being shocked then to learn about its rapid retreat. As a lover of both photography and of the mountains, spending time exploring the latter whenever I can it was a fantastic talk and I'd recommend his film 'Chasing Ice' which is based on the project to anyone if you haven't already seen it. 

Now back to topic...

This week we look at the complex issue of prediction methane emission into the future and looking at speculative predictions for future anthropogenic methane production as well as the 2 major worries for the future: methane clathrates and the risk of major methane release from defrosting permafrost regions.

Anthropogenic emissions into the future

The period of stabilisation in atmospheric methane levels experienced between 2000 and 2007 sadly appears to be over - growth has been consistent since 2008, passing the 1850ppb mark for the first time in 2014 as the figure below highlights:

Source: NOAA, 2015

Unfortunately predictions for the future aren't optimistic, with Höglund-Isaksson (2012) predicting anthropogenic emissions to break through the 400 Mt/year mark by 2027 and "an expected increase to 414 Mt methane in 2030". The same can be said for natural emissions; "Natural emissions of CH4 are likely to increase in a warmer climate; however, the magnitude and rate of change of future emissions from natural sources are largely unknown." - O'Connor et al (2010).

Source: Höglund-Isaksson, 2012

A sad reality if this is indeed the case, it highlights once again however the growing importance of curbing methane emissions. What though if methane emissions are now out of our control? That anthropogenically stimulated global warming has triggered a tipping point in the arctic in particular and that natural methane emissions from permafrost and methane hydrates are now set to be unleashed? 

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.

The power of cattle

Cattle and methane production

A teaser from Cowspiracy

The film was for a time free to watch on YouTube but has since been removed, it now costs $5 from the website www.cowspiracy.com and I would definitely say its worth paying for and watching. Cowspiracy (IMDB review here) is an independent documentary looking into cattle based agriculture, its dark impacts and why seemingly nobody wants to discuss it.

So... Cowspiracy aside what are the facts and science behind methane production from cattle agriculture? The following video produced by Harper Adams University gives an insight into how methane is produced and to the importance in feed in determining methane production:

Key points: Cows have large fore-stomach containing millions upon millions of bacteria called methanogens. These are good as they enable cows to create energy from foods we are not able to, the downside is that they create the waste product of methane. This study is looking into the role of changing feed types has on methane production - the focus of intense research at present.

So, with 1.5 billion cows in the world today:

Livestock populations of chickens and cattle

Source: The Economist (available here)

... which are thought on average to create approximately 100kg methane each per year it's clear cows alone are a major source of methane and hence driver of climate change.

To get things into perspective!

Data: NASA Goddard Institute for Space Science, Figure: BBC (available here)

What are the options for the future?

• Reducing cow numbers - and the global population adopting a diet less dependent on beef and dairy products
• Making cow production system more efficient - less time between calving and less time spent fattening cows
• Methane entrapment and use as a fuel

Before too long no longer just a joke? 

(Original source unclear) 

• Diet modification - studies such as that being undertaken at Harper Adams university in the video shown above are investigating feeds to determine variations in methane production. Others are adopting a different approach; one American study found after years of trials that natural oregano is able to reduce methane production by 40% when given to cows as a supplement at the appropriate dosage!

So... It appears our love cheese, milk, steaks, beef burgers and so on should probably be calmed if the biggest culprit of anthropogenic methane emissions is to be tamed. Or further perhaps, by adopting vegetarianism as a whole and cutting out all animal products more broadly...

"Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet" 

(Albert Einstein, Date unknown)

A spotlight on agriculture

It doesn't take much scrutiny of methane emissions data to see the significance of agriculture as the largest component, using Höglund-Isaksson (2012) data for example we see the author has come to a figure of 324Mt CH4 net for anthropogenic sources in 2005. Of this figure 68.7Mt is calculated to come from cattle alone. Pigs were responsible for 5.6Mt and other livestock around the world 22.1Mt. Rice cultivation was responsible for 26.8Mt. This comes to a total of 123Mt before cereals production other than rice is even considered - agriculture is clearly a massive driver of anthropogenic emissions.

The following figure produced with data from the GMI (Global Methane Initiative) portrays the significance of agriculture as a whole to have risen further by 2010 - contributing almost exactly 50% of total anthropogenic methane emissions:

Data: GMI, Figure: SEF (Sustainable Energy Forum), available here

As ruminant animals form over half of agriculture's contribution, of which the majority comes from cattle as highlighted by Höglund-Isaksson cattle will take on the focus of the rest of the next post.

Anthropogenic sources

Anthropogenic emissions

Following up from our post on natural emissions last week this week we turn our attention to the anthropogenic sources. As with natural emissions there is variance just as to the current level of anthropogenic emissions but most figures cite a figure of about 330 Tg/year for 2005 with papers using a more recent reference year being tending to be slightly higher. An extract from the IPCC's AR5 report is shown below:

Anthropogenic methane emissions

Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change

The paper states:

"Anthropogenic CH4 sources are estimated to range between 50% and 65% of the global emissions for the 2000s ... Anthropogenic sources are dominant over natural sources in top-down inversions (~65%) but they are of the same magnitude in bottom-up models and inventories"

This surpassing, or at least equalling in the magnitude of anthropogenic emissions compared to natural emissions is due to the continued growth of emissions in certain sectors in the decades leading up to the turn of the new millennium:

Trends in global emissions of methane (1970-2005)

Source: Emissions Database for Global Atmospheric Research

Significant increases in methane emissions from 'waste' and from 'fugitive emissions from fuel' (which includes the significant component of leaked methane from the production of fossil fuels) were mainly responsible for the continued growth of anthropogenic methane emissions in the last 3 decades of the 20th century. Since 2000 "emissions started increasing again, with an average growth rate of 1.9% per year, which has meant that since 2002, the emissions increased faster than in the last four decades. This led to a global increase of about 20% over the period 2000-2010, driven by increased coal mining by the top methane emitting country China (+50%) and increased cattle numbers in Brazil (+23%)" (IEA, 2012).

The result of these changes since 2000 mean as of 2010 the make-up of anthropogenic emissions is as follows:

Break down of anthropogenic CH4 emissions, 2010

Source: International Energy Agency, available here 

Another interesting way to interrogate anthropogenic sources of methane is geographically - by mapping its emission such as shown here in another graphic by EDGAR (Emissions Database for Global Atmospheric Research):

Mapped anthropogenic methane emissions, 2009

EDGAR, 2009

The blue shading shown in West Bengal and Bangladesh depict the particularly intense 3000-5000 tonnes CH4 emitted per 0.1degree grid cell per year with parts of China being shown to emit 5000 tonnes and above due in part to their intensive coal mining practices and rice agriculture.

So in summary of this week's post we have learnt:

• Anthropogenic methane emissions are at present thought to be approximately 350Tg/year
• This level of emission is at least equal, if not larger than the sum of all natural methane emissions
• Between 2000 and 2010 anthropogenic methane emissions increased by 20%
• Responsible for 43% of methane emissions agriculture is the largest source of anthropogenic methane which we will look into in more detail next week

Any questions or comments please don't hesitate to comment below!

Till next time...

References:

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. 

International Energy Agency, I. (2012). PART III: GREENHOUSE-GAS EMISSIONS. [online] Emissions Database for Global Atmospheric Research. Available at: http://edgar.jrc.ec.europa.eu/docs/IEA_PARTIII.pdf [Accessed 04 Dec. 2015].