The science of assessing environmental impact is a relatively young one, having only gained traction over the past few decades. Methodologies are still being developed and perfected, and best practices are still in the process of being definitively established. So it's no surprise there is disagreement among experts as to the exact environmental impact of a given industry, with the "fracking" controversy being only the latest high-profile example.
Meanwhile, however, an argument has been brewing over the past half-decade about a key environmental-impact assessment: The role of livestock production in climate change, specifically in greenhouse-gas (GHG) emissions. I've been following this off and on and it's time to take a hard look at it.
At the outset I will remind you of my potential bias (especially since such transparency, or lack thereof, comes into play here): As a vegan, I deplore the institution of animal-based foods and know that they are unnecessary for humans to eat. You may well have a different attitude about the livestock industry, which is why I encourage everyone to read everything at the links herein and see what conclusion you come to.
To recap: Livestock's Long Shadow (LLS), a 2006 report from the UN's Food and Agriculture Organization, analyzed the livestock sector and concluded that it was responsible for 18% of GHGs, more than all of human transport. In late 2009, the Worldwatch Institute released a recalculation by Jeff Anhang and Robert Goodland that found some impacts uncounted and concluded, rather, that the livestock sector was tied to 51% of GHGs - in other words, more than all other anthropogenic factors combined.
I did one E2P post on the report and refrained from going back and expounding on it after that because, given my own veganism, I wanted to err quite heavily on the side of restraint. Subsequent developments have spurred me to reexamine the issue, and I now think it's of paramount importance that everyone interested in environmentalism use something close to the 51% figure, or else present a new and compelling case against it.
It's not that there weren't cases made against the Worldwatch report (including by some vegans) very soon after publication. However, just about all of these concerns, which echoed and/or amplified some of my own, were answered in a Spring 2010 point-by-point follow-up by the two authors
At the same time, the FAO was forced to admit an error in its own calculations, pointed out in a (beef-industry-funded) UC Davis report: In its LLS assessment, the agency had included "indirect" impacts of livestock - associated or related sectors that are causally linked - but had not done the same in the case of transport. Many news organizations gleefully blared headlines that meat was now off the hook for killing the planet.
Where things get interesting is in a 2011 commentary by some of the LLS authors called "Livestock and greenhouse gas emissions: The importance of getting the numbers right" ('Herrero et al.' henceforward). Readers who may have logically expected a clarification of the data in dispute, or alternately, a discussion of different methodologies for verifying the validity of such data, may have been surprised by the content: Herrero et al. ignored the FAO controversy and concentrated instead on attacking the credibility of the Worldwatch report and lauding the "well documented" and "widely recognized" LLS, without (and here's where that transparency thing comes into play) disclosing the very salient detail that this comparison of the two studies was being co-authored by the lead author of Livestock's Long Shadow itself (plus one of that study's other authors).
Then, on its first reference to the Worldwatch report, Herrero et al. call it "a recent non-peer-reviewed report." The implication is damning: Unlike LLS, the latter report lacks scientific rigor. However, the claim is patently false. As an employee of the World Bank Group’s International Finance Corporation, Jeff Anhang was required to have peer review on any report he had his name on. Via email, I pressed Goodland and Anhang on this question and received details on the researchers and instutions who had reviewed the Worldwatch draft prior to publication, as well as those that have cited it subsequently. On the other hand, Livestock's Long Shadow may or may not have been peer-reviewed. FAO cites no such process (nor does the Herrero et al. commentary) and I was unable to find any reference to peer review in any coverage of LLS. I emailed Mario Herrero for clarification on this but have received no reply.
Similarly, on the issue of livestock respiration, which LLS omitted but Goodland and Anhang have argued for including, Herrero et al. claim that "under the Kyoto Protocol, CO2 from livestock is not considered a net source of CO2." That statement is clearly false, as the listing of manure in Kyoto's "Annnex A" shows. If Herrero et al. meant to say "CO2 from livestock respiration," they would then have needed to specify why this would be excluded from the "other" listed under "agriculture." Again, I asked Herrero for clarification on this seemingly errant claim, and will update if I receive a response.
But it's not just a couple weird false statements. "The Importance of Getting the Numbers Right" as a whole is written in a very odd, haphazard style, with relevant criticisms (founded or not) freely intermixed with those that are irrelevant.
For instance: "[Goodland and Anhang] do not quantify the lost opportunity for carbon sequestration that results from other forms of land use, such as arable crop production for human consumption, or urban development." The first of these other forms of land use is very relevant to the discussion. Urban development, though, has nothing to do with the topic at hand.
And later, the commentary claims Goodland and Anhang's proposal to replace some consumption of animal foods with that of plant foods "would contribute to habitat destruction of native grasslands, an ecosystem that harbors a number of species at risk." Whether or not that's true, the subject here - i.e. the numbers that it's imporant to get right - is livestock's impact on GHGs, not all possible environmental impacts of livestock (which are, of course, legion). Threatening at-risk species' ecosystems is way outside of the topic area.
Even more oddly, in the midst of explaining a detailed distinction between the terms "poultry production" and "poultry biomass," the authors suddenly zoom back out to say, "It should also be mentioned that despite some shortcomings of the FAO statistics, FAO still remains the only globally recognized source of data on agriculture," as if needing to remind themselves of their own validity. It's a sentiment properly expressed in the intro or conclusion that almost seems to have been accidentally copy-pasted into the poultry paragraph.
As it happens, it's exactly that emphasis on animal agriculture expertise that may undermine those authors' case for higher credibility in terms of overall eco-assessment. The journal in which their commentary appeared is "Animal Feed Science and Technology," distributed, as you'll see in the PDF linked above, by the International Livestock Research Institute, whose slogan is "Better lives through livestock." Hmmmm, no possiblity of pro-livestock bias there, right?
More to the point, as Goodland and Anhang pointed out in a "Comment" that ran as a letter to the editor of that journal, none of the authors of Livestock's Long Shadow were environmental assessment (EA) specialists - a discipline devoted specifically to, well, assessing environmental impacts. Since generating such an assessment was the entire point of LLS, this would likely have been a good idea. Goodland and Anhang, who are EA specialists (Goodland, for example, served as president of the International Association of Impact Assessment), make this case by pointing to the infamous transport error:
It appears that evidence arose of the need for EA specialists to be involved in assessing livestock and climate change when the authors of Livestock’s Long Shadow were forced to retract their comparison of livestock related GHG emissions to transport related GHG emissions, after it was revealed that their estimate of livestock related GHGs involves some lifecycle analysis, but their estimate of transportrelated GHGs involved none, only CO2 from the tailpipes of all types of transportation vehicles (The Atlantic, 2010). We propose that such an elementary error would have been less likely to occur if an EA specialist had been involved in the writing of Livestock’s Long Shadow.
Later, the two pinpoint what bothered me the most about the 2006 report:
[Herrero et al.] assert that livestock are needed to provide livelihoods and food for people; they project continued growth in the livestock sector and recommend no measure to restrict its growth; and they propose no strategy to achieve a net reduction in GHG emissions attributable to the livestock sector worldwide. They continuously fail to consider concepts considered essential in professional environmental assessment – notably the avoidance of impacts and analysis of alternatives, which would examine more environmentally sustainable pathways than livestock to provide livelihoods and food for humans.