Boucher’s main concern is the film’s assertion that at least 51% of greenhouse gas emissions come from animal agriculture.
I have argued previously that the movie was wrong in relying so heavily on that figure, which came from a 2009 World Watch magazine article by Robert Goodland and Jeff Anhang.   [Footnote ] However, there are some holes in Boucher’s arguments which, in turn, cause me some concern.
Livestock’s share of emissions
The main concern of Boucher and many others with the 51% figure is that it includes livestock respiration. Goodland and Anhang have argued that such respiration was overwhelming photosynthesis in absorbing carbon due to the massive human-driven increase in livestock numbers and removal of vegetation. Goodland subsequently stated, “In our assessment, reality no longer reflects the old model of the carbon cycle, in which photosynthesis balanced respiration”. 
Based on my interpretation of their figures, Goodland and Anhang’s non-respiration factors would have resulted in a livestock contribution of 43%.
However, Boucher also argues against other components of their estimate.
He suggests that, according to scientific “consensus” (a word he uses seven times), livestock are “currently” responsible for “about 15%” of global emissions. The paper he cites for that figure actually uses a range of 8% to 18%.  Its references, in turn, are from five papers published from 2005 to 2013, so they are hardly current, particularly when their reference periods are even earlier. The 2013 paper is from the Food and Agriculture Organization of the United Nations, which used a figure of 14.5%. 
Within the figure of 15%, Boucher’s main concern is the use by Goodland and Anhang of a 20-year time horizon for estimating the warming impact of the various greenhouse gases. Boucher’s case against that approach is poorly argued. Let’s look at his key points.
Firstly, like many others, he claims methane’s global warming potential (GWP) (although not using that term) is 25 when measured over 20 years, and 72 over 100 years. Despite claiming that those figures are based on “recent scientific consensus” (there’s that word again), his figures are out of date.
The Intergovernmental Panel on Climate Change (IPCC) used a 100-year GWP of 25 in 2007 but increased it to 34 (with climate-carbon feedbacks) and 28 (without those feedbacks) in its 2013 Fifth Assessment Report. It also increased the figure for 20 years from 72 to 86 (with climate-carbon feedbacks) and 84 (without them). 
I have argued elsewhere that a 20-year GWP for methane may be more valid than the 100-year figure used by most reporting bodies. That’s because methane, a critical factor in livestock’s climate change impacts, generally breaks down in the atmosphere to a significant extent within around 12 years. Accordingly, a 100-year GWP (which shows the average impact over a period of 100 years) greatly understates its shorter term impact.
Boucher fails to recognise that the issue is critical when considering the impact of climate change tipping points, with potentially catastrophic and irreversible consequences due to the prospect of runaway climate change over which (as the term implies) humanity will have virtually no control.
In applying the 20-year (or shorter) time horizon, Goodland, Anhang, and others (including me) are reflecting profound concern for “our children, our grandchildren, and future generations”, despite Boucher asserting that we are selfishly ignoring them.
Secondly, Boucher says that those who apply a 20-year time horizon do not count methane’s impact “in the same way that most scientists do”. In other words, they are not using “the standard method”.
He seems to have overlooked the fact that the IPCC, in its 2013 Fifth Assessment Report, acknowledged that the 100-year figure is not always appropriate, when it stated:
“There is no scientific argument for selecting 100 years compared with other choices. The choice of time horizon is a value judgement because it depends on the relative weight assigned to effects at different times.” 
Does Boucher consider the IPCC to be beyond the scope of his much-loved scientific “consensus”?
Boucher claims that the creators of Cowspiracy gave the impression that various environmental groups are part of a conspiracy because they don’t accept that livestock are responsible for 51% of global emissions. However, the issues discussed in the movie with those organisations extended well beyond that one. For example, when the interviewer questioned the sustainability of industrial scale fishing with Geoff Shester of Oceana (26:50), and rainforest destruction with Lindsey Allen of the Rainforest Action Network (31:30), the 51% figure was not mentioned.
Boucher also claims that Greenpeace politely declined to be interviewed. But why wouldn’t they be willing to discuss the issue, particularly when one of their “core values” is to “promote open, informed debate about society’s environmental choices”? 
Here’s an extract of the movie’s interview with Emily Meredith, spokesperson for Animal Agriculture Alliance (57:50), which seems to raise serious questions in relation to Greenpeace:
Question: “Does the meat and dairy industry ever support or donate to environmental non-profits?”
Emily Meredith (looking across to President and CEO, Kay Smith, who is out of sight): “I don’t know that I would want to comment on that.”
Voice of Kay Smith: “I don’t know that we would know what they donate to or don’t donate to.”
Question: “Does the meat and dairy industry ever support or donate to, say, Greenpeace?”
Emily Meredith (laughing nervously and looking across to Kay Smith): “Again, I don’t know that I would feel comfortable . . .”
If Boucher wishes to criticise Cowspiracy under the seemingly authoritative banner of the Union of Concerned Scientists, then his arguments should be based more on fact than they have been in this instance.
For my part, I will continue to argue that we will not overcome climate change unless we deal with both fossil fuels and animal agriculture, and that arguing over relative percentages may serve little purpose.
The late Robert Goodland was the lead environmental adviser to the World Bank. Jeff Anhang is a research officer and environmental specialist at the World Bank’s International Finance Corporation.
At the time of writing, the full documentary could be seen here.
 Mahony, P. “Livestock and climate change: Do percentages matter?”, Terrastendo, 15th November, 2014, https://terrastendo.net/2014/11/15/livestock-and-climate-do-percentages-matter/
 Goodland, R & Anhang, J, “Livestock and Climate Change – What if the key actors in climate change are cows, pigs, and chickens?”, World Watch, Nov/Dec, 2009, pp 10-19, http://www.worldwatch.org/files /pdf/Livestock%20and%20Climate%20Change.pdf
 Goodland, R., “Lifting lifestock’s long shadow”, Nature Climate Change 3, 2 (2013) doi:10.1038/nclimate1755, Published online 21 December 2012, http://www.nature.com/nclimate/journal/v3/n1/full/nclimate1755.html and http://www.readcube.com/articles/10.1038/nclimate1755
 Herrero, M., Wirsenius, S., Henderson, B., Rigolot, C., Thornton, P., Havlik, P., de Boer, I., Gerber, P.J., “Livestock and the Environment:What Have We Learned in the Past Decade?”, Annu. Rev. Environ. Resour. 2015. 40:177–202, https://www.researchgate.net/publication/283528658_Livestock_and_the_Environment_What_Have_We_Learned_in_the_Past_Decade and http://www.annualreviews.org/doi/pdf/10.1146/annurev-environ-031113-093503
 Gerber, P.J., Steinfeld, H., Henderson, B., Mottet, A., Opio, C., Dijkman, J., Falcucci, A. & Tempio, G., 2013, “Tackling climate change through livestock – A global assessment of emissions and mitigation opportunities”, Food and Agriculture Organization of the United Nations (FAO), Rome, pp. xii and 15, http://www.fao.org/ag/againfo/resources/en/publications/tackling_climate_change/index.htm; http://www.fao.org/docrep/018/i3437e/i3437e.pdf
 Myhre, G., Shindell, D., Bréon, F.-M., Collins, W., Fuglestvedt, J., Huang, J., Koch, D., Lamarque, J.-F., Lee, D., Mendoza, B., Nakajima, T., Robock, A., Stephens, G., Takemura, T., and Zhang, H., 2013: “Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group 1 to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change” , Table 8.7, p. 714 [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, http://www.ipcc.ch/report/ar5/wg1/
 Myhre, G., et al., ibid. pp. 711-712
 Greenpeace International, “Our Core Values”, http://www.greenpeace.org/international/en/about/our-core-values/
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