Trade-offs between blue water use and greenhouse gas emissions related to food systems: An optimization study for French adults

• Published in: Sustainable production and consumption Vol. 42; pp. 33 - 43
• Main Authors: Kesse-Guyot, Emmanuelle, Pointereau, Philippe, Brunin, Joséphine, Perraud, Elie, Toujgani, Hafsa, Berthy, Florine, Allès, Benjamin, Touvier, Mathilde, Lairon, Denis, Mariotti, François, Baudry, Julia, Fouillet, Hélène
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2023; Elsevier
• Subjects: Compromise modeling; Diet optimization; GHGe; Healthy diet; Life Sciences; Nutrient adequacy; Santé publique et épidémiologie; Water use; Water use; Nutrient adequacy; Diet optimization; GHGe; Compromise modeling; Healthy diet; compromise modelling; diet optimization
• ISSN: 2352-5509; 2352-5509
• DOI: 10.1016/j.spc.2023.09.008

Food systems face challenges from both their water and carbon footprints. Data suggest that it is possible to improve these both footprints simultaneously, but their potential conflicts and trade-offs have not been systematically explored. To this end, we here used a compromise programming approach to identify the dietary changes required to improve one and/or the other of these footprints, while ensuring nutritional adequacy and adherence to dietary guidelines, using French data on food consumption (1456 adults aged 18–64 years from the INCA 3 study) and food environmental impact (Agribalyse® database). A full range of scenarios was identified by prioritizing the two objectives differently, giving weight from 0 % to 100 %, by 5-% steps, to the improvement in greenhouse gas emissions (GHGe) over the improvement in blue water use (BWU). Overall, we have shown that it is possible to significantly reduce both BWU and GHGe compared to observed levels. The BWU reduction ranged from 14 % to 36 % with increasing prioritization, while the simultaneous GHGe reduction varied less, from 52 % to 44 % with decreasing prioritization. The consumption of some foods varied according to the priority given to BWU over GHGe reduction (namely, vegetables, fruit juice, dairy products, eggs, refined cereal, substitutes, offal and potatoes). In contrast, meat consumption (beef, pork, poultry and processed meat) was systematically removed, while the consumptions of offal and dairy products remained moderate in order to meet nutrient reference values. Fish, whole grains, and fruit also remained relatively constant across scenarios due to the constraints based on dietary guidelines. Whatever the scenario, the modeled diets were more plant-based than the observed diet from which they differed significantly (only 23–31 % of common food consumptions), and were therefore healthier (63–76 % reduction in the distance to theoretical minimum risk of chronic diseases). To conclude, while focusing solely on BWU reduction induces a joint GHGe reduction that is near-maximal, the reverse is not true, showing that there is good alignment but also some divergence between these objectives.