POO POWER! Part 1: Cars powered by poo!

For those of you who like to drive but are concerned about the rising costs of fuel and environmental issues around its production, this is for you!

This video and this news article in the Guardian explains all!

A water treatment plant in Bristol, part of the Wessex Water group of companies, is producing methane from human waste flushed down the loo! The biogas could resolve some sustainability issues around fuel for cars, as the man at the end of the video says:

 "As long as there are people, cows and chickens, they'll be methane."

I agree...

However! Even though biogas is sustainable and is beneficial in terms of dealing with increasing amounts of waste that we will produce, the fundamental problem is the fact that it is still a form of combustion; combustion = CO₂. 

So, on the one hand it's sustainable and uses the methane that would otherwise contribute a more to global warming in the short term. On the other, it doesn't address the underlying dependence on carbon dioxide producing processes which will inevitably exacerbate climate change. 

PEE POWER! Part 1: MCFs

The moment we have all been waiting for is here!

Pee can be used as a fuel... revolutionary! The article  looks at the potential of using the compounds in urine to produce electricity using microbial fuel cells (MCFs). These little packages of micro-organisms use the biomass in urine and converts it into a form of renewable energy; renewable in the sense that as long as we're living, we're peeing!

Ieropoulos et al. (the authors of the article) go on to highlight the importance of this research and the wider implications of this technology. It offer one was or extracting N, K and P nutrients from urine which are often at high concentrations and out them to good, fertilising use; rather than spending billions to treat this waste water straight away, we could utilise more of the power from it and it will push treatment costs down; energy security, it just so happens where more people live, who all demand energy, more pee is, what a coincidence!

Animal urine can also be used... the possibilities are endless! But don't start filling up your car with the yellow stuff just yet...

Fossilised farts (and other agroGHGs)! Part 3: The critiques of fart records: it’s ALL NATURAL.

Now both articles (Fuller et al., 2011; Ruddiman et al., 2011) and their side of the debate have critiques. From these graphs (from Ruddiman et al., 2011) they become evident:

In the first (A) graph you can see that the relationship between CH₄ concentrations and population is not constant. Initially CH₄ per capita increased proportionally, then methane rose steadily whilst population was rising exponentially. This decoupling is down to (what Ruddiman et al. 2011 note from Ellis and Wang in 1997) different land production efficiencies and priorities. With increasing intensification techniques, like rearing cattle, more land and plants are needed as well as primitive ruminants who haven’t been selectively bred to maximise meat or milk production yet. These inefficiencies which increase CH₄ release (IPCC, 2006) where only dealt with during the latter half of the Holocene, this is just one argument supporting anthropogenic methane emissions prior to the Anthropocene; this decouples methane and population, whilst explain the change in rates. Also land use per capita dropped, as seen in the second graph, that is not to say that the early human pastoralists had large herds of cows farting across the once green, bread-basket of the Sahara, it just highlights primitive techniques of farming. Quantifying the contributions of CH₄ into rice agriculture and livestock rearing category is hard as more research needs to be undertaken (Fuller et al., 2011; Singarayer et al., 2011).

Picking up on the point of the inter-polar gradient (IPG), Chappellaz et al. (1997) investigated the difference between the polar records of methane concentrations. Studying the Arctic GRIP ice core and the Antarctic BYRD and D47 ice cores, they attributed the changes in the IPG to initially (5.7 and 2.5 – 5 ka) lower atmospheric CH₄ levels due to the on-going drying of the tropical regions combined with massive peat land growth in the northern boreal regions after 5 ka. With a recent period (ca. 1 ka) increases due to increased wetness and significant anthropogenic emissions. Harder et al. (2007) investigates this further, coupling a GCM with information on the sinks of methane; volatile organic compounds (VOC) and the sea (changes in sea surface temperature, SST). Another vital sink, the largest in fact (and one I hope to investigate further is the hydroxyl radical (­^●OH). Stressing the importance of changes in the various other sources and sinks, Harder et al.’s research show that the IPG changes are the result of dynamics within the ‘methane cycle’, between the balance between the sources/sinks. However, they draw attention to the necessity to improve understanding about how methane may react with other GHGs especially considering the fact that the hydroxyl radical is the sink for many other GHGs. Any anthropogenic influence on the changing methane concentrations either at 5 ka or in the IPG has been sidelined.

This point is underlined by Singarayer et al. (2011) as concluding remarks describe the lack of model evidence successfully calibrating predicted and observed data sets, with an anthropogenic input providing a correct outcome. It goes even further saying, and I quote:

“The late Holocene increase in methane can be primarily ascribed to increasing emissions from the Southern Hemisphere tropics. In the late Holocene, unlike the last interglacial, these increases are not counteracted by equivalent decreases in Northern Hemisphere emissions. We suggest therefore that direct anthropogenic influences are not necessary to explain the late Holocene methane record.”

Rather than the idea of cows farting (as it is quite hard to believe!); Singarayer et al. (2011) looks into possible overlooked variables. Exploring such variables like: glacial extent, and how it may effect subtle changes in the source regions; seasonality of the SH tropical wetland, and the resulting emissions; but most importantly, the link to the Eemian period where the orbital configuration is comparable to the present (and where models attempting to show the anthropogenic link fall short). They reaffirm their point that SH emissions were not counteracted with NH CH₄ emission decreases.

Even Burns (2011) discusses the possibility of an ‘all-natural’ 5 ka methane rise due to tropical produce methane causing the deviation from the expected. Burns looks at speleothem records to infer monsoonal strengths. It shows that the monsoons did migrate southwards, so making the highly productive tropics and areas south of the equator increasingly waterlogged and, ergo, greater CH₄ productive. It does seem that it is a one or the other theory approach… Neo can only take either the red or blue pill. There is no such thing as a purple one. But here, I would suggest that even though evidence is in favour of an all-natural approach. In my opinion one cannot exclusively write out the other, and the debate will go on for ages; but archaeological evidence shows the techniques expansion. Whether you like it or not, ruminants fart, producing methane, as well as humans might I add!

I would like to think that thousands of years ago my ancestors around the Mediterranean were herding farting sheep, farting cows and farting chickens, contributing to increasing methane concentrations in the atmosphere. It was a simpler time; it was a less fartier time!

Reference list for the 3 parts of Fossilised Farts (and other agroGHGs)!

Brook, E. J., Sowers, T. and Orchardo, J., 1996, Rapid variations in atmospheris methane concentration during the past 110,000 years, Science, 273, 1087-1091 pp.

Burns, S. J., 2011, speleothem records of changes in tropical hydrology over the Holocene and possible implications for atmospheric methane, The Holocene (special issue), 1-7 pp.

Chappellaz, J., Blunier, T., Kints, S., Dallenbach, A., Barnota, J., Schwander. J., Raynaud, D. and Stauffer, B., 1997, Changes in the atmospheric CH­₄ gradient between Greenland and Antarctica during the Holocene, Journal of Geophysical Research, 102, D13, 15,987-15,997 pp

Ellis, E. C. and Wang, S. M., 1997, Sustainable traditional agriculture in the Tai Lake region of China, Agriculture Ecosystems and Environment, 61, 177-193 pp.

Fuller, D. Q., Manning, K., Castillo, C., Kingwell-Banham, E., Weisskopf, A., Qin, L., Sato, Y. and Hijmans, 2011, The contribution of rice agriculture and livestock pastoralism to prehistoric methane levels: An archaeological assessment, The Holocene, 21, 743-759 pp.

Harder, S. L., Shindell, D. T., Schmidt, G. A. and Brook, E. J., 2007, A global climate model study of CH₄ emissions during the Holocene and glacial-interglacial transitions constrained by ice core data, Global biogeochemical cycles, 21, GB1011, 1-13 pp.

IPCC, 2006, CH4 Emissions from enteric fermentation,in Guidelinesfor National Greenhouse Gas Inventories Volume 4 Agriculture, Forestry andOther Land Use, writtenby Gibbs, M. J., Conneely, D., Johnson, D., Lasse, K. R. and Ulyatt M.J., , 297-320 pp. 

Ruddiman, W. F., Kutzbach, J. E. and Vavrus, A. J., 2011, Can natural or anthropogenic explanations of late-Holocene CO₂ and CH­₄ increases be falsified? The Holocene, 21, 865-879 pp.

Schlit, A., Baumgartner, M., Schwander, J., Buiron, D., Capron, E., Chappellaz, J., Loulergue, L., Schupbach, S., Spahni, R., Fischer, H. and Stocker, T., 2010, Atmospheric nitrous oxide during the last 140,000 years, Earth and Planetary Science Letters, 300, 33-43 pp.

Singarayer, J. S., Valdes, P. J., Friedlingstein, P., Nelson, S. and Beerling, D. J., 2011, Late Holocene methane rise caused by orbitally controlled increase in tropical sources, Nature, 470, 82-86 pp.

Sowers, T., 2010, Atmospheric methane isotope records covering the Holocene period, Quaternary science Reviews, 29, 213-221 pp.

Wolff, E. W., 2011, Methane and Monsoons, Nature, 470, 49-50 pp.

Fossilised farts (and other agroGHGs)! Part 2: The expansion of Livestock and the debate around the Anthropocene.

Now, studies by Brook et al. (1996); Schlit et al. (2010); Sowers (2010); Burns (2011); Singrayer et al. (2011) and Wolff (2011) all show ice core records and other proxies (analogues for past environmental records) like speleothem (calcite deposits) to show CH₄ and other GHGs like N₂O over the Holocene (11 ka BP; Sowers, 2010) to 140 ka (Schlit et al. 2010). These records show the link between precessional cycles and CH₄ concentrations; but up until 5 ka, the CH₄ concentration deviated from what is expected due to the precessional cycle. The NH has been at an insolation minima due to the precessional cycle being in a NH negative stage (i.e. the southern hemisphere, SH, has more intense summers and winters).

This discrepancy between expected and observed therefore does not follow the natural process. Now shoot me if you must, but I agree with research put forward by Ruddiman, and I am joining in the argument/debate on the Anthropocene. In an article by Ruddiman et al. in a special issue Holocene published in June 2011 (where some of the other 2011 articles from Holocene are taken) attempts to falsify anthropogenic and natural increases in CO₂ and CH₄. The case states that only one other (stage 11) deglaciation has a similar increase in methane after the initial peak and decreasing tail (which would be due to a natural or at least non-anthropogenic process). All of the records (except stage 11) show a decrease of CH₄ in line with NH summer insolation minima. Stage 1 (our current Holocene/Anthropocene) does not follow this trend. Due to the rise and spread of humans through the globe, the establishment of civilisations and the first age of modernity through agricultural development, Ruddiman et al. (2011) and Fuller et al. (2011) show that it is expansion of agricultural practices of wet-rice farming and livestock intensification which is responsible for the anomalous rise in atmospheric methane contribution. This is significant for this blog as it shows (even among scientists like myself… ok I am only a student) humans have had an effect on the greater environment and the Earth’s ecosystems through a variety of anthropogenic process; relating this to livestock they include deforestation (increasing CO₂) and increased agricultural production (increasing CH₄ and later with the green revolution N₂O). This rise is evident 5 ka; that is why I believe that humans have had a significant impact on the earth before 250 yrs BP, it’s been 5 ka that’s how far the Anthropocene extends. This is shown in the graph taken from Fuller et al. 2011. 

Graph showing CH₄ predicted (NH insolation records) and measured CH₄ in GRIP ice core over time.

The Fuller et al. (2011) article looks at agricultural (pastoral and arable) contributions to prehistoric methane levels, using archaeological evidence to match it to the GHG records. This graph from their article shows the deviation from the predicted methane concentrations from the GRIP ice core. The black square points represent actual methane concentrations. The difference between the two data sets is ‘potentially’ cow farts and other anthropogenic processes (causing the deviation). They go deeper, investigating the spatial distribution of the technologies and knowledge of the more intensive (and greater GHG producing) agricultural techniques over time. Here are some maps showing the expansion of livestock practices:

Southern and Eastern Asia Livestock technique dispersal Fuller et al. 2011

Africa Livestock technique dispersal Fuller et al. 2011 

Southern Asia Livestock technique dispersal Fuller et al. 2011

The increased expansion of these farming practices means that more food was able to be cultivated, for direct food (like rice) or indirect food (like livestock feed).  This archaeological evidence shows the actual distribution of the increasing anthropogenic CH₄ sources. Another integral point (that will be elaborated on in part 3 of Fossilised farts) is the fact that the inter-polar gradient (IPG) between ice core records of CH­₄ concentration in Greenland and Antarctica begin to equate (Chappellaz et al., 1997; Burns, 2011). If for instance the NH boreal arctic polar circumference began to emit greater amounts of CH₄, then Greenland’s ice cores will have a greater concentration of the gas than Antarctica’s cores due to the proximity and difficulty of inter-polar diffusion. The fact that the IPG is levelling out shows that the source is low latitude; agricultural expansion into Africa, Southern Asia and South-Eastern Asia can be an explanation to this. Coupled with greater CH₄ emissions from the amazion basin (due to a stronger SH summer) and other low latitude CH₄ sources; this could explain the 5 ka rise. 

Fossilised farts (and other agroGHGs)! Part 1: The natural sources of methane in the past.

Records of trapped gas (of which some are fossilised farts) come from ice cores. GISP2 and GRIP (central Greenland) and the Vostok cores (Antarctica) show GHG levels fluctuating for millennia; stadials and interstadials (Brook et al., 1996). Focusing on methane and nitrous oxide (nitrous oxide will become increasingly significant during the green revolution and greater use of fertilisers), the role which livestock domestication and increased production has played on levels of those gases has been increasing over the late Holocene, correlating with the increasing human population and complementarily food demand.

Butt (pardon the pun), there are a variety of natural and other anthropogenic process which produce CH­₄ (and N₂O). To add to the debate about when humans had a global effect on the planet, we must be able to distinguish the gases between the various human and natural process, and that’s  where the magic happens…err, the science I mean.

The earth has always been able to regulate the gases in the atmosphere thanks to dynamic equilibrium. A long time ago, in a land quite close to home, early Homo sapiens sapiens lived as hunter gatherers and there was no such thing as an economic crisis. Over the last 140 ka (Schlit et al., 2010), atmospheric concentrations of greenhouse gases has varied naturally (as they have done before human mastery of emitting vast amounts of GHGs) due to feedback processes which are triggered by either external (orbital cycles, volcanic eruptions) or internal (organisms, Dansgaard-Oeschger cycles, Heinrich events, oceans) processes (Brook et al. 1996).

In the prior blogs I (hope to) have shown the main anthropogenic sources of the GHGs methane and nitrous oxide (as well as CO­₂, but due to its greater abundance in the atmosphere and number of sources is hard to quantify what proportion is due to livestock processes). These two gases in particular are good indicators of livestock production and other agricultural process as they can have a signal specific to the process of formation and as natural methane is dependent on the precessional cycle of the earth (explained further in part 2) it is relatively easy to predict and categorise as it increases and decreases in line with the earth’s precession. The main sources of methane come from the humble bacteria. Decomposers, who (as the name suggests) decompose organic matter (dead plants, leaves, bodies…err cow poo or rice stalks, to name but a few) anaerobically (without oxygen) which produces methane.

The best way of removing oxygen from soil (where tonnes of organic matter meet with anaerobic decomposers) is through water-logging/increasing the water table. Like any other organic process involving enzymes; the warmer the environment, the greater the rate of the process occurs, ergo more methane.

More organic matter + higher temperatures + greater water logged soils + decomposer bacteria = a load of natural methane!

The greatest sources of natural methane are large areas on earth (where else?) where temperatures are sufficient to allow decomposition to occur, have large stores of organic carbon in the soil and are highly water-logged. The source of the organic material is the crux of the matter, if it comes from cows stomachs via the rectum (LOL) then increasing the cow population directly increases methane produced from anaerobic decomposition, as well as their farts of course.

Tropical/sub-tropical and boreal (peat land) wetlands are the largest sources of natural methane. Other natural sources include termites, wild fires, wild animals farting, methane hydrate release and oceans (Ruddiman et al., 2011). In the ice core records, the direct correlation between the CH₄ concentration and precessional cycle boils down to the northern hemisphere summer insolation. The precessional cycle dictates the amount of summer temperatures in each hemisphere, governing the seasonal intensity (temperatures/precipitation) and the monsoons. As the direction of the tilt of the earth towards the sun changes cyclically over 22-26 ka (Ruddiman et al., 2011), when the northern hemisphere (NH) is pointed towards the sun when at the same time the earth is closest (the perihelion) to the sun then the NH summer insolation is high, increasing temperatures and precipitation, as seen in speleothem records across the tropics (Burns, 2011). Due to the inter tropical convergence zone (ITCZ) shifting northwards, NH precipitation increases the water logged state of the tropical/sub-tropical rainforests and greater insolation heats and melts permafrost in the boreal band across North America and Eurasia; paving the way for those nasty bacteria to unlock the frozen carbon in the form of the by-product that is CH₄.

You see… all those old-fashioned climate sceptic and climate change deniers are right… it’s not the fault of humans; we just have to destroy all those evil decomposer-bacteria that produce this bad gas, get the Dettol at the ready!

Contributions to global GHG emissions in a flow chart!

This flow diagram shows global GHG emissions from different sectors including agriculture; each sector is then divided up into end use/activity which produce GHGs, in this case 'livestock and manure' which is accountable for 5.1% of total GHG emissions directly (i.e farting); not including indirect forms of emissions from deforestation, feed or indeed energy used in their transportation (this is a separate flow).

From this image it is easy to see where the largest cuts in emissions could be from energy generation, especially when considering we have alternatives to conventional (but deadly) fossil fuel combustion.

The image is from: http://www.wri.org/chart/world-greenhouse-gas-emissions-2005.