We are responding to the misinformation being propagated about our study, “Implications of Future US Diet Scenarios on Greenhouse Gas Emissions,” published in 2020.1  In this study, we explore the effect on greenhouse gas emissions (GHGE) of a hypothetical reduction in the consumption of animal-based foods in the U.S. diet and a replacement with plant-based foods. We have learned of various media reports that have incorrectly linked our study findings to President Biden’s Climate Plan.  We wish to set the record straight about our study.

Key points:

1) To our knowledge, there is no connection between our study and Joe Biden's Climate plan. This appears to be an association made erroneously by the Daily Mail that has been picked up widely.

2) Our study merely identifies opportunities for emissions reductions that are possible from changes in our diet. By no means does it suggest that these changes in diet would be required to meet climate goals.

Relevant background:

• Our Center conducts research on carbon-reduction strategies and policy, and we have reviewed the recent factsheet posted on President Biden’s Climate Plan.2  President Biden’s Climate Plan does not directly refer to diet shift as a carbon reduction strategy, so the linkage to our study is baseless.  Here is the reference to agriculture: “The United States can reduce emissions from forests and agriculture and enhance carbon sinks through a range of programs and measures including nature-based solutions for ecosystems ranging from our forests and agricultural soils to our rivers and coasts. Ocean-based solutions can also contribute towards reducing U.S. emissions.”
  
   
• The hypothetical scenarios examined in our study offer insights into how different types and levels of diet shift can influence greenhouse gas emission reductions.  They were NOT developed as specific policy recommendations.  In Scenario 4 of our study (see below) we explored a 90% reduction beef in addition to a 50% reduction in other meats. Scenario 4 would achieve a 50% reduction in diet related greenhouse gas emissions associated with agricultural production, but this is NOT a specific recommended policy for achieving a 50% reduction in U.S. carbon emissions. 
  
   
• Diet shift is one important strategy to reducing our GHGE. The 2019 US GHGE are distributed across sectors as follows: 10% from agriculture, 29% transportation, 25% electricity generation, 23% industrial sector, 13% commercial and residential sectors (not including electricity use in buildings).  The opportunities for reducing emissions vary across sectors. However, agriculture represents 38% of anthropogenic methane emissions in the US, with 36% originating from livestock (enteric fermentation and manure management). Targeting short-lived greenhouse gases such as methane is seen as an important near-term climate action strategy in order to reduce the damage due to climate change over the next few decades and to slow climate feedback loops3. Therefore, addressing contributions from food and agriculture, particularly the amount of animal-based foods in the US diet, can be seen as an urgent short-term goal.

Implementing carbon reduction strategies across all economic sectors will be critical to accelerating emissions reductions to meet IPCC 1.5 C targets. We need to be aggressive on carbon reduction actions on all fronts to avoid the most adverse effects of climate change. We are in a climate emergency and urgent actions are required.

We examined diet shift through four scenarios projected to 2030 in our study:

1.        The baseline average diet remains unchanged to 2030

2.        Meat and poultry consumption increases per USDA projections

3.        Consumption of animal-based foods (red meat, poultry, fish/seafood, eggs, dairy, and animal-based fats) decreases by 50%, and is substituted with plant-based foods

4.        Same as scenario 3, but beef decreases by 90%, instead of 50%.

Key findings:

The total emissions associated with producing the average US diet amounts to 5.0 kg CO2 eq. per person per day. Whereas red meat (beef, pork, lamb) represents 9% of the calories available from this diet, it contributes 47% of the GHGE. All animal-based foods combined (red meat, poultry, fish/seafood, eggs, dairy, and animal based fats) represent 82% of the baseline diet GHGE. According to USDA, the average American consumed 133 pounds of red meat and poultry in 2016. USDA projects slight increases in per capita red meat and poultry consumption in the US in 2028 (scenario 2); assuming other foods unchanged, this raises the carbon footprint to 5.14 kg CO2 eq. per person per day.

Cutting the intake of all animal-based foods by half and replacing with equivalent quantities of plant based foods (scenario 3) results in a 35% decrease in GHGE from the baseline, to 3.3 kg CO2 eq per person per day, which would mean 224 million metric tons less emissions per year in 2030, equivalent to the annual emissions of 47.5 million of today’s average passenger vehicles. Under this scenario 3, red meat represents 36% of the total emissions. Further reducing consumption of beef to only 10% of the baseline value, and subsequent replacement with plant-based proteins (scenario 4), cuts the diet-related emissions to 2.4 kg CO2 eq per capita per day, aby 51 % decrease from the baseline diet. Under this final scenario 4, the average American consumes 50.1 pounds of meat and poultry per year. If these diet shifts occur in a linear transition to 2030, the cumulative reduction in scenario 3 and 4 would be 1634 and 2408 million metric tons, respectively. Details of the study including carbon intensity of meats and plant based proteins are available in the report which can be accessed through the Center for Sustainable Systems website.

Research Sponsorship

The research funding for our study was provided by the Center for Biological Diversity. 

The greenhouse gas emissions factors used in our study were developed in part through a grant from the Wellcome Trust which supported a research collaboration between the University of Michigan (Marty Heller and Greg Keoleian PIs) and Tulane University (Diego Rose, PI).  See reference 4.

Center for Sustainable Systems

The Center for Sustainable Systems evaluates the environmental impacts of products and technology and has been researching the food system sustainability since 1999.  More information on the mission and research activities of the Center are available at http://css.umich.edu/

We are an endowed Center at the University of Michigan based in the School for Environment and Sustainability.  We are NOT part of the “Department of Agriculture” at the University of Michigan as was indicated by Fox News.  The University of Michigan does not have academic department with that name.

References: 

(1) Martin Heller, Gregory Keoleian, Diego Rose “Implications of Future US Diet Scenarios on Greenhouse Gas Emissions” Center for Sustainable Systems, Report No. CSS20-01 University of Michigan, Ann Arbor, Michigan, January 13, 2020. http://css.umich.edu/sites/default/files/publication/CSS20-01.pdf

(2) FACT SHEET: President Biden Sets 2030 Greenhouse Gas Pollution Reduction Target Aimed at Creating Good-Paying Union Jobs and Securing U.S. Leadership on Clean Energy Technologies link: https://www.whitehouse.gov/briefing-room/statements-releases/2021/04/22/fact-sheet-president-biden-sets-2030-greenhouse-gas-pollution-reduction-target-aimed-at-creating-good-paying-union-jobs-and-securing-u-s-leadership-on-clean-energy-technologies/ accessed April 26, 2021.

(3) Shindell, D., N. Borgford-Parnell, M. Brauer, et al. (2017). "A climate policy pathway for near- and longterm benefits." Science 356(6337): 493-494.

(4) Heller, MC, A Willits-Smith, R Meyer, GA Keoleian, D Rose, "Greenhouse gas emissions and energy use associated with production of individual self-selected U.S. diets.” Environmental Research Letters (2018) 13(4): 044004, DOI: 10.1088/1748-9326/aab0ac.

Gregory A. Keoleian

Director, Center for Sustainable Systems

School for Environment and Sustainability

University of Michigan

Martin Heller

Research Specialist, Center for Sustainable Systems

School for Environment and Sustainability

University of Michigan

AP Fact-Checking Article: Biden climate plans don’t include red meat restrictions