Responses to Livestock's Long Shadow

There has been a huge amount of media coverage on the criticism of the FAO's 2006 Livestock's Long Shadow report by some US academics at the University of California Davis.

The main points of the criticism are as follows:

1. The Mitloehner paper points out that LLS adopts a life cycle analysis approach to quantifying livestock related emissions, but does not do the same for transport, even though it compares livestock emissions with those of transport and says that the former is greater. 
2. The paper says that US livestock emissions are much lower as a percentage of the US emissions total than the global estimate. It cites the following figures: 5.8% (or 413 Tg CO₂-eq yr_1) is associated to the entire agricultural sector. Specifically, agriculture in the United States represents 32% of the anthropogenic CH4 emission and 68% of the N₂O emission (EPA et al., 2009). Within the United States, approximately 198 Tg CO₂-eq yr_1 or 2.8% is associated with livestock (i.e. enteric fermentation and manure management). 
3. The report repeatedly compares the 18% and 3% figures figures even though the former is based on LCA and the latter not – i.e. it makes exactly the same error as it the LLS that it criticises.
4. Land use change: a large percentage of the emissions attributed to livestock in LLS were related to land use change. Most deforestation arises in the developing world and not the developed world which is actually seeing some afforestation. So land use change related emissions are not applicable to the UK context. See the FCRN/WWF for more on land use change.
5. LLS (FAO et al., 2006) does not account for ‘‘default’’ emissions. Specifically, if domesticated livestock were reduced or even eliminated, the question of what ‘‘substitute’’ GHGs would be produced in their place has never been estimated. Livestock provide not only meat, dairy products and eggs, but also wool, hides, and many other value-added goods and services. Livestock are often closely integrated into mixed and some landless (e.g., landless dairy) farming systems as consumers of crop by-products and sources of organic fertilizer, while larger animals also provide power for ploughing and transport. Therefore, to estimate accurately the ‘‘footprint’’ of all livestock, ‘‘default’’ emissions for nonlivestock substitutes need to be estimated and compared to livestock emissions. 
6. An adding up exercise: according to the Mitloehner paper, US livestock related emissions (direct only) generate 198 Tg CO₂-eq yr. This is about 3% of the global livestock emissions calculated by FAO using a full life cyce analysis approach (which includes processing transport, fertiliser production, land use change etc). The US population is about 4.5% of the world population. If you assume (reasonably) that a full LCA would increase the US’s reported livestock emissions by a fair amount, then you could argue that the US’s contribution to global livestock related GHG emissions is pretty much at least proportional to its population and the fact that its direct (although not necessary indirect) land use change burden is unlikely to be of the same order of magnitude as seen in the developing world is thanks to the fact that there are the US population is very low relative to its vast land area.
7. The Mitloehner paper says that the US should concentrate on cleaning up its transport sector rather than worrying about how much meat and dairy foods it eats. Since the US transport sector generates 1887 Tg CO₂-eq yr (ie. about 4-5% of global emissions as they were during the time of the LLS publication) this is a fair point but this perhaps says more about the magnitude of the US’s need to reduce emissions from all sectors very drastically than anything else.

Frank Mitloehner has emphasized that he believes more accurate coverage of his paper (compared to other media coverage) is to be found here.