A flagship UN report on livestock emissions is facing calls for retraction from two key experts it cited who say that the paper “seriously distorted” their work.
The UN Food and Agriculture Organization (FAO) misused their research to underestimate the potential of reduced meat intake to cut agricultural emissions, according to a letter sent to the FAO by the two academics, which the Guardian has seen.
Paul Behrens, an associate professor at Leiden University and Matthew Hayek, an assistant professor at New York University, both accuse the FAO study of systematic errors, poor framing, and highly inappropriate use of source data.
Hayek told the Guardian: “The FAO’s errors were multiple, egregious, conceptual and all had the consequence of reducing the emissions mitigation possibilities from dietary change far below what they should be. None of the mistakes had the opposite effect.”
Agriculture accounts for 23% of global greenhouse gas emissions, most of which are attributable to livestock in the form of methane from burps and manure, and deforestation for grazing and feed crops. As global meat production leapt by 39% in the first two decades of this century, agricultural emissions also rose by 14%.
At the Cop28 climate summit in December, the FAO published the third in a series of studies of the livestock emissions problem. As well as reducing the FAO’s estimate of livestock’s contribution to overall global heating for a third consecutive time, it used a paper written by Behrens and others in 2017 to argue that shifts away from meat eating could only reduce global agri-food emissions by between 2 and 5%.
Behrens’s paper from 2017 assessed the environmental impacts of government-backed nationally recommended diets (NRDs) of the time, which have since become outdated. Many countries, such as China and Denmark, have drastically reduced their recommended meat intake since then, while Germany now proposes a 75% plant-based diet in its NRD.
Behrens says “voluminous evidence” from larger environmental reports which recommended reductions in meat content, such as the Eat-Lancet Planetary Health Diet, were ignored, according to the letter.
“The scientific consensus at the moment is that dietary shifts are the biggest leverage we have to reduce emissions and other damage caused by our food system,” Behrens told the Guardian. “But the FAO chose the roughest and most inappropriate approach to their estimates and framed it in a way that was very useful for interest groups seeking to show that plant-based diets have a small mitigation potential compared to alternatives.”
Of more than 200 climate scientists surveyed by Behrens and Hayek for a recent paper, 78% said it was important for livestock herd sizes to peak by 2025 if the world was to stand a chance of preventing dangerous global heating.
As well as using obsolete NRDs, the scientists say the FAO report “systematically underestimates” the emissions-cutting potential of dietary shifts through what the letter calls a “series of methodological errors”.
The authors say these include: double-counting meat emissions until 2050, mixing different baseline years in analyses, and channelling data inputs that inappropriately favour diets allowing increased global meat consumption. The FAO paper also skips over the opportunity cost of carbon sequestration on non-farmed land.
Hayek said the FAO inappropriately cited a report he co-authored that measured all agri-food emissions, and applied it to livestock emissions alone. “It wasn’t just like comparing apples to oranges,” he said. “It was like comparing really small apples to really big oranges.”
Correspondingly, the mitigation potential from farming less livestock was underestimated by a factor of between 6 and 40, he said.
The FAO is the world’s primary source for agricultural data, and its reports are routinely used by authoritative bodies such as the UN’s Intergovernmental Panel on Climate Change (IPCC). But the FAO is also mandated to increase livestock productivity so as to bolster nutrition and food security, arguably creating a conflict of interests.
Former officials have accused the FAO of censoring and sabotaging their work when it challenged livestock industry positions. A recent FAO roadmap to making the sector sustainable also omitted the option of reducing meat intake from a list of 120 policy interventions.
That paper received praise from meat industry lobbyists, one of whom called it “music to our ears” when it was released at Cop28.
An FAO spokesperson said: “As a knowledge-based organisation, FAO is fully committed to ensuring accuracy and integrity in scientific publications, especially given the significant implications for policymaking and public understanding.
“We would like to assure you that the report in question has undergone a rigorous review process with both an internal and external double-blind peer review to ensure that the research meets the highest standards of quality and accuracy, and that potential biases are minimised. FAO will look into the issues raised by the academics and undertake a technical exchange of views with them.”