The research, published in the Proceedings of the National Academy of Sciences (PNAS), used data compiled from a number of US government sources, including the Departments of Agriculture, the Interior and Energy, and applied what the authors, which included Professors Gidon Eshel, Alon Shepon, Tamar Makov and Ron Milo, described as a uniform methodology to compare the environmental footprint across a range of livestock production processes.
They claimed the results showed that while the environmental impacts of dairy, poultry, pork and eggs were generally comparable, beef required “28 times more land, 11 times more irrigation water, five times more greenhouse gas emissions, and six times more reactive nitrogen fertiliser” than any other livestock-based production system.
Professor Eshel, who advocates for a shift to plant-based diets, said that while studies had shown the high environmental cost of livestock production, people continued to “eat animal-based products with an ever-increasing gusto”. He hoped the new research would help improve both personal consumer choices, and agricultural policies of governments.
He said the work improved on previous studies: “Though numerous studies have addressed some subsets of the issue, they mostly used data from individual farms – typically one or, at most, a handful. Yet farms differ markedly geographically, season to season and year to year, and are thus imperfectly representative of national means. In sharp contrast, we used the reverse, top-down approach, analysing national level data.
“Further, while our predecessors mostly addressed one environmental burden at a time, we addressed simultaneously, and under a single uniform methodological roof, greenhouse gas emissions, water and land use, and reactive nitrogen discharge, opening a multi-dimensional window into the environmental performance of the nation’s livestock industry.”
While Professor Eshel hopes the study will provoke a sea change in global diets, and deliver “global food security and food access equality”, US beef leaders have dismissed the study’s findings.
Kim Stackhouse-Lawson, director of sustainability research with the National Cattlemen’s Beef Association (NCBA), said: “The National Cattlemen’s Beef Association, as a contractor to the Beef Checkoff Program, has recently completed the largest lifecycle assessment ever conducted for a food supply chain, which showed that the beef industry in the US is on a path of continuous improvement. Between 2005 and 2011, the US beef industry improved environmental and social sustainability by 7%.
“The PNAS study represents a gross over-simplification of the complex systems that make up the beef value chain, a point which the authors acknowledge. The fact is the US beef industry produces beef with lower greenhouse gas emissions than any other country. The conclusions in this study only serve to confuse consumers about the fact that including beef as part of a healthy diet can co-exist with a healthy environment in the US, as recently evidenced by the beef lifecycle assessment.”
The study and the resulting media reports also provoked anger within the UK meat industry. Nick Allen, sector director with English beef and lamb levy body Eblex, said: “This is a US study and it is disappointing that commentators in the media have failed to address the fact that our production systems in the UK are very different.
“Our rain-fed pasture system means we have one of the most efficient and sustainable livestock production systems in the world. In the UK, cattle and sheep primarily convert grass, which cannot be used to feed people, into nutritious food for our growing population. We have very little reliance on irrigation; in fact it takes just 67 litres of water to produce 1kg of beef.
“There are also additional environmental benefits of grazing ruminants, not least in terms of landscape management and maintaining biodiversity, yet livestock production still comes in for undue criticism.”