One issue that often comes up in discussions about climate and agriculture is methane emissions. As part of their digestive processes ruminants produce methane which according to climate scientists, is disastrous for global warming. Ecology & Farming takes a dive into the swamp of the methane controversy.
Methane (CH4) is a much stronger greenhouse gas than carbon dioxide (CO2) and is therefore the main target for reducing agricultural greenhouse gas emissions. This raises questions about the environmental credentials of organic farming. Ruminants form the basis of many organic systems: converting roughage into manure. For many years the European Commission has subsidised campaigns to promote the consumption of chicken meat. Not so much because chicken ‘is the ideal meat’, but because the production of chicken meat imposes the least climatic burden.
Take a chicken, put some grain in it, and within a few weeks there is chicken on your plate. No methane emissions, but a very high feeding efficiency; all in all a fine production process. To optimise it further, you can move away from agriculture completely and imitate the process in a laboratory: the egg of Columbus and a technocratic gem − if you consider agriculture and nutrition as a linear production process.
This is not exactly an organic solution. First of all, because organic thinking is not focussed on linear processes, but circular ones. You cannot run a viable or independent farm with just chickens and chicken manure. Growing cereals and taking the chicken manure back to the land is also a downward spiral, as it would eventually impoverish the soil. To ensure sustainable soil fertility one needs organic matter and therefore roughage conversion. And, because some 60% of the world’s agricultural land is only suitable for growing grass, which can only be converted into human nutrition by cows and other ruminants, these are the ‘jewels’ of agro-ecology.
But what about the methane these ruminants produce? Is that the stain on the reputationnot the fly in the ointment? The Intergovernmental Panel on Climate Change (IPCC) is the agency responsible for coordinating climate research and publishing the results. It expresses all greenhouse gases in CO2 equivalents. Methane has a higher ability to block heat radiation from the Earth than CO2 (Global Warmth Potential, GWP), but has a much shorter life span. The GWP is simple to determine in a laboratory: determining the life span is much trickier. Methane is very reactive in the atmosphere and sources of methane are diverse. This makes the lifetime estimates very uncertain. The IPCC (1) and researchers from the Max Planck Institute (2) estimate this uncertainty at between 35-65%! Because the IPCC has to deliver hard figures to politicians, they prefer to use a fixed lifetime for methane, to be able to convert it into CO2equivalents. In other words the benchmark which several institutes use to analyse climate change and to measure greenhouse gases and the resilience of agriculture are based on a very uncertain figure.
This is not the only quicksand under the climate calculations. There is a fundamental difference between CO2 and CH4 emissions: increasing emissions of CO2 lead to a permanently increased concentration in the atmosphere because it is a chemically stable, final product that does not change. However, methane is a chemically unstable product which is active in the atmosphere. As more methane is produced, more is decomposed and a new balance is created. Higher methane production also leads to more conversion of methane, so that an increase in methane does not lead to a cumulative warming effect. That’s an essential difference with CO2, and the reason why converting methane to CO2equivalents represents a fundamental error within climate calculations. One of the ridiculous conclusions is the insinuation that the livestock sector has as great an impact on climate as the extremely intensive traffic in the Netherlands or other highly industrialised countries. Methane is unanimously designated as a greater culprit than CO2 in discussions about global warming. Some researchers believe that there are political motives behind this. The US National Research Council (3) mentions that by focusing on methane, one can theoretically achieve faster results, with less drastic measures for industrial economic development.
This puts the methane discussion in a very different light. You can find methane everywhere where intensive organic conversions take place. It is released from the extraction of fossil energy, in swamp formation and in the digestive system of ruminants. In earlier stages of the Earth, plant life captured a huge amount of carbon, partly in the form of methane which is now entering the atmosphere (e.g. shale gas). Methane certainly has a short term climatic impact. In order to limit methane production we would need to replace cows with pigs and chickens. From a climatic point of view, this is putting the cart before the horse: we need cows to solve the problem. The core of the climate problem is that we are burning carbon that has been captured inside the Earth for billions of years, and putting it back into the atmosphere. What we need are measures to fix carbon sustainably in the soil. The cow is one of the resources we can deploy to do this. It is important that we use the cow as a roughage converter. It is true that methane emissions are a side effect of humus production in cow manure. But that humus production leads to the sustainable sequestration of carbon in the soil. It is important to encourage farmers to feed their cows roughage. Cows always have and always will produce methane. Methane plays a very small part in the climate story, and should be seen in relation to the rest. Holistic thinking is one of organic farming’s strong points. Climate change poses a challenge to organic farmers. Our focus should not be on methane, but on finding alternatives to the consumption of fossil energy. That is the real challenge!
1. Wigley, TML, 1998: The Kyoto Protocol: CO2, CH4 and climate implications. search Geophysical Letters 25, 2285-2288
2. Hein r., P.J. Crutzen and M Heimann (1997): An inverse approach to investigate the global methane cycle, Global mospheric Biochem. Cycles 11 (1), 43-76
3. National Research Council, 2009: Stabilization Targets for Atmospheric greenhouse gas Concentrations (quoted from www.nap.edu)
4. Intergovernmental Panel on Climate Change: Climate Change 2007
5. FAO: Livestock’s Long Shadow; Livestock’s role in climate change and air pollution