This working paper is the last in the World Resources Institute’s series on Creating a Sustainable Food Future, where they evaluate several different production and consumption approaches to close the 70 percent “food gap” between the crop calories available in 2006 and expected calorie demand in 2050. The series has been looking at production-focused solutions, such as sustainably increasing crop yields and livestock pasture productivity, as well as consumption-focused approaches, such as reducing food waste, achieving replacement-level fertility, and reducing demand for bioenergy that makes dedicated use of crops and land. In this last working paper, the role and potential of shifting the diets of populations who consume high amounts of calories, protein, and animal-based foods is evaluated. Specifically, the report considers three interconnected diet shifts, each of which includes a range of sub scenarios:
The report authors use the GlobAgri model to quantify the land use and greenhouse gas consequences of different foods, and then analyse the per person and global effects of the three diet shifts (using 2009 consumption data) on agricultural land needs and greenhouse gas emissions. It finds that:
Reducing overconsumption of calories, and so reducing overweight and obesity is important for human health, but this diet shift contributes less to reducing agriculture’s resource use and environmental impacts than the other two shifts.
Reducing overconsumption of protein by reducing consumption of animal-based foods resulted in the largest benefits, as it applied to a relatively large population and across all animal-based foods.
Reducing consumption of beef specifically resulted in significant benefits, and would be relatively easy to implement, since it only affects one type of food. Additionally, some high-consuming countries have already reduced per person beef consumption from historical highs, suggesting that further change is possible.
The paper describes global effects in terms of agricultural land use and greenhouse gas emissions in more detail (relative to the 2009 reference of an average diet of a high-consuming country):
For reducing overconsumption of calories:
- If obesity and overweight was halved land use would decrease by 90 million hectares while greenhouse gas emissions from agricultural production would decrease by 2 percent.
- In the scenario where obesity is eliminated and overweight halved land use would decrease by 140 million hectares and greenhouse gas emissions would decrease by 3 percent.
In addition, the avoided future emissions from land-use change—assuming diet changes were sustained over time—would be 19.9 billion tons CO2 e for halving obesity and overweight and 34.6 billion tons in the scenario where obesity is eliminated and overweight halved (compared to total global greenhouse gas emissions in 2009 which were 44 billion tons CO2 e.)
For reducing overconsumption of protein by reducing consumption of animal-based foods and increasing the proportion of plant-based protein in diets:
- In the scenario Ambitious animal protein reduction, total agricultural land use declines by 13 percent (nearly 650 million hectares) and greenhouse gas emissions from agricultural production decline by 10 percent. Assuming diet changes were sustained over time, this scenario would avoid 168 billion tons of emissions of CO2e.
- For the scenario Traditional Mediterranean Diet total agricultural land use land production-related greenhouse gas emissions were very modest and declined by less than 0.5 percent since overall animal-based food consumption did not actually drop by much in this scenario relative to reference.
- In the Vegetarian scenario where half of the population of high-consuming regions shifts to vegetarian diets total agricultural land use declines by 150 million hectares, and greenhouse gas emissions decline by 4 percent. (This scenario was applied to a smaller number of people (only 440 million versus 1.9 billion in the Ambitious animal protein reduction scenario)
For reduction in beef consumption:
- Under all three beef reduction scenarios, world pastureland declines by around 200 to 300 million hectares in 2009, representing 6 to 9 percent of all pastureland and 4 to 6 percent of total agricultural land.
- Crop land only slightly decreases and there is a slight increase in crop land in the scenario where there is a shift from beef to pork and poultry (as these two need more crop-based feeds).
- Each scenario results in reductions in greenhouse gas emissions from agricultural production, from 4 to 6 percent relative to reference. In addition, the avoided future emissions from land-use change—assuming the diet changes are sustained over time—range from 51 to 98 billion tons CO2 e (compared to total global emissions 2009 of 44 billion tons of CO2 e).
With a projected 25 percent of all crops (measured by calories) dedicated to animal feed in 2050, the study calculates that the Ambitious Animal Protein Reduction scenario could reduce the food gap from 70 percent to about 50 percent—significantly reducing the challenge of sustainably feeding nearly 10 billion people by mid-century.
The report also adds the effects of land-use change (resulting from people’s dietary choices) to agricultural greenhouse gas emissions to see how these impact the overall CO2e associated with diets. They find that the emissions from clearing additional land to feed an additional person eating the US diet are equal to 17 years’ worth of that person’s energy-related CO2 emissions.
The report introduces a protein scorecard ranking foods from lowest (plant-based foods) to highest impact (beef) and the Shift Wheel, a framework to tackle the crucial question of how to shift people’s diets specifically targeted to actors in the food industry; retail and food service sectors. It also sets out specific recommendations for the food industry to apply the Shift Wheel.
Ranganathan, J., Vennard, D., Waite, R., Lipinski, B., Searchinger, T., Dumas, P,. Forslund, A., Guyomard, H., Manceron, S., Marajo-Petitzon, E., Le Mouël, C., Havlik, P., Herrero , M., Zhang, X., Wirsenius, S., Ramos, F., Yan, X., (2016). World Resources report: Shifting Diets for a Sustainable Food Future, Creating a Sustainable Food Future, Installment Eleven, World Resources Institute
Read the full report here.
You can also find two of the previous reports in this WRI series in the FCRN research library:; see The great balancing act and Indicators of Sustainable Agriculture: A Scoping Analysis.