Why is it even an issue worth discussing in a blog dedicated to the world of excrement? Well the fundamental problem we face, not just as a species, but as inhabitants of earth, is climate change. We humans use the planet as our only home, kitchen, garden and toilet. Like any other confined space, when you begin to change the chemical make-up of the gas enclosed in that volume, you begin to change the overall physical, chemical and thermal properties of that gas. In the case of excrement, methane (CH4) and nitrous oxide (N2O) is produced through a variety of processes (as is carbon dioxide, CO2) which contribute to the greenhouse effect (Popp et al., 2010). Carbon dioxide is the most significant anthropogenic produced GHG due to the sheer quantity that is emitted into the atmosphere from human activities.
However, as I touched upon in the previous post, over 100 years, the same amounts CO2, CH4, and N2O have varying potencies due to their thermodynamic properties. This property is applied as a ration of heat trapped by one unit mass of the GHG compared to one unit mass of CO2; this is called the Global Warming Potential (GWP) (Pitesky et al., 2009). As it a ratio, CO2 has a GWP of 1; CH4 has a GWP of 23 (in the previous post I wrote that the potency of methane was 20 times that of carbon, it was wrong sorry!); N2O is 296 (FAO, 2006). From this data, it shows how important methane and nitrous oxide produced from livestock production, and in particular from poo, will be an increasing problem, not just as the total number of GHGs (CO2 and non-CO2) is set to increase from projected and modelled figures (Popp et al., 2010). In addition, with populations estimated to reach 9 billion by 2055 (World Bank, 2011) and increasing qualities of life reflecting greater demand for meat in the diet; livestock rearing is set to increase; that equates to a whole load of shhhhh… excrement.
The United Nations Food and Agriculture Organisation (FAO) commissioned a report on the impact livestock production has on the planet,Livestock’s long shadow (FAO, 2006). As a whole, livestock (either directly or indirectly) is responsible for 18% of total anthropogenic GHG emissions (FAO, 2006); those figures broken down into individual GHG include:
· Carbon dioxide (CO2) 9% of global anthropogenic emissions.
· Methane (CH4) 35 – 40% of global anthropogenic emissions.
· Nitrous oxide (N2O) 65% of global anthropogenic emissions.
· Ammonia (NH3) 64% of global anthropogenic emissions.
However, as I will investigate later on in the blog (or further towards the top of the blog), Excretion and everything does not just play an integral role to GHG emissions, it also plays a vital role in the nutrient cycle, particularly phosphorous and nitrogen. Phosphorous (P), as well as nitrogen (N) in the form of nitrates and other vital macronutrients like magnesium (Mg), potassium (K) and calcium (Ca) are required as well as a variety of other micro nutrients (Robinson, 2004). Phosphorous is often a limiting factor in plant production, due to its vital role as an ingredient in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the building blocks of life; and in the Adenine triphosphate (ATP) which is the primary method of intracellular energy release and storage (Biology-Online, 2011), so we can all move, keep warm and most importantly… LIVE! Also, specifically to plants, P is necessary for healthy root growth, vital for the uptake of water and the other nutrients. The role fertiliser plays is significant, and indeed focusing on one of the nutrients, phosphorous, an increasingly important point has surfaced. Livestock (cows for example) need to eat; feed is created from plants; high amounts of land and biomass is required to produce vast amounts of feed; limited land resources dictates more intensive farming methods; greater dependence on higher yields; synthetic fertilisers created to provide the vital nutrients for plant growth; mining of phosphates from a finite source requires large amounts of energy whilst depleting the source.
As you can see, just from scratching the surface, cow (and other animals’) farts and poo pose a more serious problem than the humorous connotations applied to them suggest. Over the next few weeks and posts I hope to show you a greater insight in to the world of climate change, nutrients (re)cycling, pollution, eutrophication, renewable energy and many, many more uses, and subjects, which poo influences.
This blog may overlap with others, in fact it will. A post by fellow GEOG3057 blogger Emma (I hope she is Ok with me using her name), touches on the renewable potential of methane gas from… well cow farts. Another blog dedicated to the debate around biofuels can also shed light on the increasing diversification of energy sources, by another fellow GEOG3057 blogger Yulia. But those topics are for another time!
Next I hope to give you an insight into past methane releases and the relationships between the potent GHG and the atmosphere, looking at palaeo records of methane…essentially fossilised cow farts… Ok well some of the methane was produced by pre-modern time cows farting. Until then… watch those deadly emissions!
References:
Biology Online, 2011, ATP Definition. Available from: http://www.biology-online.org/dictionary/Atp. [Online] accessed 24/10/2011.
Pitesky, M. E., Stackhouse, K. R. and Mitloehner, F. M. 2009, Clearing the Air: Livestock’s contribution to climate change, Advances in Agronomy, 103, 1-40 pp.
Popp, A., Lotze-Campen, H., Bodirsky, B., 2010, Food consumption, diet shifts and associated non-CO2 greenhouse gases from agricultural production. Global Environmental Change, 20, 451-462 pp.
Robinson, G. 2004, Geographies of Agriculture: Globalisation, restructuring and sustainability. Harlow: Pearson Publications Limited.
If you find this sh.... stuff interesting then you might find these blogs interesting to!
Please check them out, as I try to myself!
Agriculture: Human Health and Earth Health: http://robs-agriculture.blogspot.com/
Biofuels: Way Ahead or Blind Alley: http://biofuels-wayaheadorblindalley.blogspot.com/
Fixing Climate Change: http://fixingclimatechange.blogspot.com/
