Joint Letter: Expressing serious concern over the FAO’s recent Pathways Report

8 Jul 2024 Letter

Dr. Qu Dongyu


UN FAO, Viale delle Terme di Caracalla

00153 Rome, Italy

Cc: Maria Helena M.Q. Semedo (Deputy Director-General), Beth Bechdol (Deputy Director-General), Maurizio Martina (Deputy Director-General), Beth Crawford (Chief Scientist), Thanawat Tiensin (Director of Animal Production and Health Division), Clemencia Cosentino (Director, Office of Evaluation), Corinna Hawkes (Director, Division of Food Systems and Food Safety), Kaveh Zahedi (Director, Office of Climate Change, Biodiversity and Environment), David Laborde (Director, Agrifood Economics and Policy Division)

Dear Dr. Dongyu,

We, the undersigned, are writing to express serious concern over the FAO’s recent report Pathways towards Lower Emissions (hereafter referred to as the Pathways report), following the significant methodological errors and inappropriate sources of evidence identified by academics Paul Behrens and Matthew Hayek, whose research was distorted in the report, affecting the integrity of its conclusions. We set out recommendations related to the Pathways report and the upcoming 2050 Roadmap report, the need for transparency in the GLEAM methodology, and engagement on the nutritional adequacy of different healthy sustainable diets.

1. Methodological errors in the Pathways report

We support Behrens and Hayek’s call for the report to be retracted, methodological errors rectified and for the FAO to use more appropriate and up-to-date studies that look into the emissions reduction potential of dietary shift. As part of this process, the FAO should engage with independent academics and experts from civil society to ensure the robustness of this report.

The numerous errors in the Pathways report have the cumulative effect of erroneously downplaying the emissions mitigation potential of dietary change towards lower consumption of animal products – Behrens and Hayek indicated that the FAO has likely underestimated the emissions mitigation potential of dietary change compared to a business-as-usual (BAU) 2050 scenario by a factor of between 6 and 40 – based on Clark et al.’s (2020) modelling, the direct emissions mitigation potential from dietary change in line with the EAT-Lancet diet is closer to 3.10 Gt CO2 equivalent per year, rising to 6.22 Gt CO2eq per year if the carbon sequestration potential from ecosystem restoration on spared land is factored in, compared with a 2050 BAU baseline.

We do not repeat the Pathways report errors here at length, as these are analysed in detail in Behrens and Hayek’s original letter, but summarise them in the Annex to this letter.

It is extremely concerning that such basic failures of analysis made it into a published FAO report without being flagged during the peer-review process – indicating the need for a comprehensive investigation of how these serious errors and systemic biases were allowed, and an overhaul of the FAO’s internal review processes to ensure improved methodological rigour in future reports. We are calling on the FAO to publish a full methodology and a list of authors and reviewers for its future reports.

The FAO’s estimate that dietary change has the potential to reduce livestock emissions by only 0.19-0.53 Gt CO2-eq per year compared to a BAU 2050 baseline are completely out of step with the conclusions of other United Nations institutions and general scientific consensus. The International Panel on Climate Change (IPCC) found, with high confidence, that a shift to more plant-based diets could mitigate GHG emissions by between 0.7 – 8 GtCO2-eq per year, with higher reductions in meat and dairy leading to higher emission reductions. For instance, the IPCC cites a study which estimates that a flexitarian diet (75% of meat and dairy replaced by cereals and pulses, with only one portion of red meat a week) would reduce global emissions by approximately 5 GtCO2-eq per year – over 9 times higher than the FAO’s estimate. Since this study uses current levels of meat and dairy consumption as a baseline, emissions mitigation would be considerably higher compared to a BAU 2050 projection. A recent survey of over two hundred climate scientists and food and agriculture experts, over half of whom have authored IPCC reports, found that:

● Global livestock emissions need to be reduced by 50% by 2030 and 61% by 2036, with faster and deeper reductions in higher-income countries, in order to limit global warming in line with the Paris agreement;

● 78% of the experts surveyed said that absolute global livestock numbers need to peak by 2025;

● Reducing human consumption of livestock products and reducing the number of livestock animals were ranked as having the biggest potential for reducing livestock emissions, whilst intensification of livestock was rated as the measure with lowest potential.

Other global institutions have also backed more ambitious action on dietary change and livestock systems – such as the World Bank’s recent report Recipe for a Liveable Planet which recommends a shift away from subsidies for red meat and dairy production, and the Task Force on Reactive Nitrogen of the United Nations Economic Commission for Europe (UNECE) Convention on Long-range Transboundary Air Pollution recommended that halving European meat and dairy consumption is one of the best ways to reduce European nitrogen pollution.

2. Influence of Pathways on the upcoming 2050 Roadmap report

In light of the above, we ask whether the FAO intends to use the Pathways report analysis to inform its upcoming 2050 Roadmap report, and the recommendations therein. If this is the case, we have grave concerns that the serious errors in the Pathways report will, unless rectified, seriously compromise the credibility of the Roadmap report, and of the FAO itself. The Roadmap is a report of great significance which will have global influence on governments’ and companies’ plans to reduce emissions from food systems, and it is therefore of utmost importance that it maintains the highest standards of scientific rigour – which are conspicuously and egregiously absent in the Pathways report calculations of the emissions mitigation potential of dietary change. These concerns have also been voiced by FAIRR, a global investor network with a membership of $70 trillion in collective assets of support, which has stated that “concerns raised by the authors [Behrens and Hayek] extend beyond just the one paper” to the 2050 Roadmap report.

We thus recommend that the release of the 2050 Roadmap be delayed until the FAO has engaged in serious dialogue with experts and civil society in a reflective process to assess what went wrong in the Pathways report – and adopt more robust, inclusive and transparent processes in the creation of the next instalment of the 2050 Roadmap report. In its response to The Guardian’s reporting on the Behrens and Hayek request for a retraction of the Pathways report, the FAO said it would “look into the issues raised by the academics and undertake a technical exchange of views with them.” We urge the FAO to honour its commitment and schedule a technical exchange promptly with Behrens and Hayek, and to engage with other independent academic experts and civil society to ensure its future calculations are robust. We are concerned about reports by former FAO officials claiming that they have been sidelined by the FAO for espousing dietary change as a solution to reducing livestock emissions, following lobbying from livestock businesses and high meat- producing countries – and urge the FAO to ensure an open and objective engagement with experts.

3. The need for transparency in the GLEAM methodology:

More broadly, we are surprised that the FAO’s GLEAM estimates for the total emissions from livestock globally have declined significantly over time due to revisions to the model, despite considerable growth in livestock production volumes during this period. GLEAM estimates of total global livestock emissions have declined from 7.1 GtCO2-eq per year (14.5% of total anthropogenic greenhouse gas emissions) in 2013’s Tackling Climate Change Through Livestock to 6.2 GtCO2-eq (12% of global emissions) in GLEAM 3.0 (2023). The Pathways report attributes this to “differences in methodology, input data and global warming potential (GWP) values” and gives topline explanations of data sources, but greater transparency of the calculations is required. We call on the FAO to publish 1) the data sources and calculations used to arrive at the GLEAM statistics and 2) the identities of experts involved in production of the GLEAM figures, with disclosure of any potential conflicts of interest. Hayek has stated that there is an “alarming lack of validation” from verifiable atmospheric data for the FAO’s GLEAM data. We thus call on the FAO to collaborate with academic experts to cross-check modelled estimates of livestock emissions against verifiable atmospheric data, to ensure the accuracy of GLEAM statistics. The scientific rigour of GLEAM is particularly important in light of the global influence of GLEAM, which is used by many countries and companies in national and corporate reports.

4. Dietary change and nutrition:

Finally, we urge the FAO to increase its engagement with nutritional experts and other UN agencies, such as the World Health Organisation, to investigate further the evidence behind the nutritional adequacy and benefits of healthy diets containing less animal products and more plant-based foods, including in the Global South. As noted in the Annex, the official dietary recommendations of many countries support lower-meat diets as nutritionally adequate – for instance, Danish guidelines recommend that 350g meat per week is adequate.

We welcome your response to these queries and recommendations. Following your written response, we would also be happy to offer a meeting to discuss the points raised.


Logos of organisational signatories:

[Can be seen in the downloaded version of the letter]

Full list of organisational signatories:

1. Carina Millstone, Executive Director, Feedback Global

2. Frank Mechielsen, Executive Director, Feedback EU

3. Nusa Urbancic, CEO, Changing Markets

4. Shefali Sharma, Global Project Lead, Greenpeace

5. Faustine Bas-Defosse, Director for Nature, Health and Environment, European

Environmental Bureau (EEB)

6. Sophia Murphy, Executive Director, Institute for Agriculture and Trade Policy

7. Merel van der Mark, Senior Campaigner, Rainforest Action Network

8. Monique Mikhail, Campaigns Director, Agriculture & Climate Finance, Friends of the Earth


9. Janet MacGillivray, Executive Director, Seeding Sovereignty

10. Alessandro Ramazzotti, Researcher on agriculture and energy finance, International

Accountability Project

11. Doug Hertzler, Senior Policy Analyst, ActionAid USA

12. David Garrahy, Head of External Affairs, World Animal Protection

13. Philip Lymbery, Global CEO, Compassion in World Farming International

14. Jurjen de Waal, Senior Director, Mighty Earth

15. Ladd Connell, Environment Director, Bank Information Center

16. Marta Messa, Secretary General, Slow Food

17. Nico Muzi, Managing Director, Madre Brava

18. Umo Isua-Ikoh, Coordinator, Peace Point Development Foundation-PPDF

19. Ariel Brunner, Regional Director, BirdLife Europe and Central Asia

20. Amelia Linn, Director of Global Policy, Mercy For Animals

21. Carolina Galvani, Executive Director, Sinergia Animal

22. Mia MacDonald, Excutive Director, Brighter Green

23. Stephanie Feldstein, Population and Sustainability Director, Center for Biological Diversity

24. Lisa Tostado, Agrochemicals and Fossil Fuels Campaigner, Center for International

Environmental Law (CIEL)

25. Sani Lake, Director, JPIC Kalimantan

26. João Camargo, Campaigner and Researcher, Corporate Europe Observatory

27. Renee Morga, Social Justice Capital, Adasina Social Capital

28. Frank Luvanda, Environmental Expert, Sustainable Holistic Development Foundation

(SUHODE Foundation)

29. Jan Willem van Gelder, Director, Profundo

30. Claire Ogle, Head of Campaigns, Policy and Research, The Vegan Society

31. Anita Krajnc, Global Campaign Coordinator, Plant Based Treaty

32. Daemon Ortega Froysa, Policy & Project Officer, SAFE – Safe Food Advocacy Europe

33. Avnish Thakrar, National Coordinator, Hindu Climate Action

34. Peer Cyriacks, Head of land use, Deutsche Umwelthilfe

35. Ecologistas en Acción

36. Ruth Westcott, Campaign manager, climate and nature emergency, Sustain, the alliance for

better food and farming

37. Valentin Krancevik, Board member, Let’s Do It, Romania!

38. Rune-Christoffer Dragsdahl, Secretary Genera, The Vegetarian Society of Denmark

39. Susana Fonseca, Vice President, ZERO – Association for the Sustainability of the Earth System

40. Piotr Barczak, Circular Economy Program Manager, Polish Zero Waste Association41. Marko Košak, Zero Waste Programme Coordinator, Vice President, Zelena akcija / Friends of

the Earth Croatia

42. Alexandra Ghenea, President, Ecoteca NGO

43. Gilliane Le Galli, President, Alofa Tuvalu

44. Dr Shireen Kassam, Director, Plant-Based Health Professionals UK

45. Anna Spure, COO, Green REV Institute

46. Tessa Clarke, CEO & co-founder, Olio

47. Sani Lake, Director, JPIC Kalimantan

48. Dr. Hope Ferdowsian MD MPH, President, Phoenix Zones Initiative

49. Dr. Tushar Meht, Director, Plant Based Data

50. Suzy Russell, Coordinator, The Community Supported Agriculture Network UK

51. Morgan Janowicz, Director, Future Food 4 Climate

52. Gaja Brecelj, Managing Director, Umanotera

53. Julie Janovsky, Vice President for the Farm Animal Welfare and Protection, Humane Society


54. Juan Carlos Salinas Menacho, Secretario de Conflictos, Asociación Unión de Talleres 11 de


55. Kim O’Dowd, Climate Campaigner, Environmental Investigation Agency

56. Barbara Ujlaki, President, Vegan Society Luxembourg asbl.

57. Elias Kindle, Managing Director, Liechtensteinische Gesellschaft für Umweltschutz

58. György Szabó, Zero Waste Program Manager, Humusz Szövetség

59. Sauro Martella, Founder, VEGANOK

60. Renata Balducci, President, ASSOVEGAN

61. Gaja Brecelj, Director, Umanotera

62. Dr. Zahra Kassam, Director, Plant-Based Canada

63. Branislav Moňok, Chairman, Friends of the Earth – SPZ, Slovakia

64. Brigitte Gothière, Executive Director, L214

65. Jack Norris, R.D., Executive Director, Vegan Outreach

66. Tracy Childs, Co-Director, PlantDiego

67. Sandra Higgins, Director, Go Vegan World

68. Roberto Juárez, General Director, Youth Building The Future Global

69. Maja Hrovat, President, Slovenian Vegan Society

70. Karlee Schnyder, Co-Director (Outreach), Real Food Systems Youth Network

71. Kaspar Schuler, Director, CIPRA (International Commission for the Protection of the Alps)

72. Marc Alexander, Member of leading group, Climate Express Belgium

73. Julia Thielert, Scientific Employee, Menschen für Tierrechte Baden-Württemberg

74. Jaka Kranjc, Secretary General, Ekologi brez meja

75. Caroline Rowley, Director, Ethical Farming Ireland

76. Robbie Lockie, CEO & Founder, Freedom Food Alliance

77. Taylison Santos, Executive Director, Fórum Nacional de Proteção e Defesa Animal

78. Lisa Levinson, Campaigns Director, In Defense of Animals

Individual signatories (please note: for these signatories support is given in individual capacity, not on behalf of institution):

1. David Michel, CT State Representative, CT General Assembly House District 146

2. Daina Bray, Clinical Lecturer in Law, Yale Law School*

3. Pete Smith, Professor, University of Aberdeen

4. Jennifer Jacquet, Professor, University of Miami

5. Gidon Eshel, Research Professor of Environmental Physics, Bard College, NY, USA

6. Rosie Green, Professor of Environment, Food and Health, London School of Hygiene &

Tropical Medicine

7. Robert C. Jones, Professor, California State University, Dominguez Hills

8. Joseph Poore, Research Fellow, University of Oxford

9. Laura Scherer, Assistant Professor, Leiden University

10. Jan Dutkiewicz, Assistant Professor, Pratt Institute

11. David R Williams, Lecturer in Sustainability and the Environment, University of Leeds

12. Kurt Schmidinger, Geophysicist and Food Scientist, University Vienna

13. Harry Aiking, Associate Professor, Institute for Environmental Studies, Vrije Universiteit Amsterdam

14. Prof. Dr. Ir. Peter H. Verburg, Professor Environmental Geography, Institute for

Environmental Studies, VU University Amsterdam

15. Anthony Fardet, Senior Research Scientist

16. Pere Pons, Environmental Sciences, University of Girona

17. Philipp Pattberg, Director, Amsterdam Sustainability Institute

18. Harj Narulla, Barrister, Doughty Street Chambers

19. John Sanbonmatsu, Associate Professor of Philosophy, Worcester Polytechnic Institute

20. Benjamin Phalan, Head of Conservation, Parque das Aves, Brazil

21. Sena Crutchley, MA, CCC-SLP, AP Associate Professor, UNC Greensboro

22. Dr. Maria E. Theodorou, MD, PhD (plant biology) FRCPC (Internal Medicine), Dipl. ABLM,

Dipl. ABOM

23. Sarah Keating MD

*Yale affiliation provided for identification purposes; position not endorsed by Yale University or

Yale Law SchoolAnnex – Errors in the Pathways report:

The Pathways report includes numerous errors, all of which have the cumulative effect of erroneously downplaying the emissions mitigation potential of dietary change towards lower consumption of animal products. Of particular concern are the serious methodological errors which appear to have been committed – which are mostly calculations erroneously comparing fundamentally incomparable data in a way which leads to extremely inaccurate results:

● Double counting meat emissions to 2050 – once in the BAU baseline projections for increased meat consumption by 2050, and then again in the estimation of emissions mitigation potential of dietary change which erroneously factors in both projected increases in meat consumption in some countries and decreases in others;

● In the calculation of net changes in livestock emissions as a result of dietary change, erroneously including emissions from increases in vegetable, fruit and nut consumption which are unrelated to substituting meat and dairy in diets;

● Mixing different baseline years in its analysis – emissions savings compared to current diets are falsely represented as potential emissions savings compared to 2050 BAU projections;

● Inappropriately comparing emissions reduction of nationally recommended diets (NRDs) to a total emissions quantity from an incomparable paper. In addition to these methodological errors, the FAO has made a series of highly inappropriate, narrow and distorting modelling choices:

● Conflates sustainable healthy diets with nationally recommended diets (NRDs) – most of which do not factor sustainability into their design.

● Fails to model the emissions mitigation potential of the many available models of sustainable healthy diets which do factor in emissions and other sustainability criteria (such as the EAT-Lancet diet);

● Ignores the opportunity cost of livestock production and the associated opportunities for carbon sequestration on land spared by dietary change;

● Within the limitations of NRDs, makes choices which further limit their potential, such as:

o Uses NRDs which have since become obsolete – with many having since been updated to recommend lower meat consumption. Some examples include:

▪ Spanish Guidelines from 2022 now recommend 0-3 meat portions/week

▪ German guidelines from 2024 now recommend no more than 300g meat per week

▪ Danish from 2021 guidelines recommend that 350g meat per week is adequate

▪ China has also systematically decreased recommended levels of meat intake over

time, with the latest 2022 revision recommending only 300-500g meat per week.

o Uses the mid-range rather than the lower-range value for meat intake from NRDs – thus failing to accurately represent the potential meat reduction, even within the out-of-date NRDs.

● Uses a study which assumes very high emission intensities for increases in plant-based products:

● Uses a single (inappropriate) study, ignoring the large scientific literature available on the emissions mitigation potential of sustainable diets.


References [in text footnotes for references available in the downloaded letter]

1 Paul Behrens and Matthew Hayek, “Letter to Dr Tiensin: Retraction Request – FAO’s Pathways toward Lower Emissions

Report,” April 9, 2024,


2 Arthur Neslen, “UN Livestock Emissions Report Seriously Distorted Our Work, Say Experts,” The Guardian, April 19, 2024,

sec. Environment,


3 Michael A. Clark et al., “Global Food System Emissions Could Preclude Achieving the 1.5° and 2°C Climate Change

Targets,” Science 370, no. 6517 (November 6, 2020): 705–8,; Behrens and Hayek,

“Letter to Dr Tiensin: Retraction Request – FAO’s Pathways toward Lower Emissions Report,” April 9, 2024


4 P.R. Shukla et al., “Climate Change and Land: An IPCC Special Report on Climate Change, Desertification, Land

Degradation, Sustainable Land Management, Food Security, and Greenhouse Gas Fluxes in Terrestrial Ecosystems –

Technical Summary” (IPCC, 2019), 49,


5 C. Mbow et al., “Food Security. In: Climate Change and Land: An IPCC Special Report on Climate Change, Desertification,

Land Degradation, Sustainable Land Management, Food Security, and Greenhouse Gas Fluxes in Terrestrial Ecosystems”

(IPCC, 2019), Chapter 5 p488.

6 Helen Harwatt et al., “Options for a Paris-Compliant Livestock Sector: Timeframes, Targets and Trajectories for Livestock

Sector Emissions from a Survey of Climate Scientists” (Harvard Law School Animal Law and Policy Program, March 2024),

7 The World Bank, “Recipe for a Livable Planet: Achieving Net Zero Emissions in the Agrifood System,” World Bank, 2024,

8 Adrian Leip et al., “Appetite for Change: Food System Options for Nitrogen, Environment & Health. 2nd European

Nitrogen Assessment Special Report on Nitrogen & Food” (Task Force on Reactive Nitrogen of the UNECE Convention on

Long-range Transboundary Air Pollution., December 20, 2023),

9 FAIRR, “FAIRR Comments on Request by Academics for Retraction of FAO Report | FAIRR,” FAIRR, April 30, 2024,

10 Neslen, “UN Livestock Emissions Report Seriously Distorted Our Work, Say Experts.”

11 Arthur Neslen, “‘The Anti-Livestock People Are a Pest’: How UN Food Body Played down Role of Farming in Climate

Change,” The Guardian, October 20, 2023, sec. Environment,


12 Pierre J. Gerber and Food and Agriculture Organization of the United Nations, eds., Tackling Climate Change through

Livestock: A Global Assessment of Emissions and Mitigation Opportunities (Rome: Food and Agriculture Organization of the

United Nations, 2013),

13 FAO, “GLEAM 3 Dashboard,” FAO, 2023, 3,

14 Neslen, “‘The Anti-Livestock People Are a Pest.’”

15 Ministry of Food, Agriculture and and Fisheries of Denmark, “The Official Dietary Guidelines – Good for Health and

Climate” (Ministry of Food, Agriculture and Fisheries of Denmark, 2021),


16 ASEAN, “Food-based dietary guidelines – Spain,” Food and Agriculture Organization of the United Nations, 2022,

17 Deutsche Gesellschaft für Ernährung e. V., “DGE-Ernährungskreis,” Deutsche Gesellschaft für Ernährung e. V., 2024,

18 Ministry of Food, Agriculture and and Fisheries of Denmark, “The Official Dietary Guidelines – Good for Health and

Climate” (Ministry of Food, Agriculture and Fisheries of Denmark, 2021),


19 Chinese Center for Disease Control and Prevention, “Eight Key Recommendations from Dietary Guidelines for Chinese

Residents (2022),” Chinese Center for Disease Control and Prevention, 2022,

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