Eating your greens: a global sustainability assessment

Abstract

The importance of healthy diets is woven into the fabric of the Sustainable Development Goals, although there is no clear metric to define it. Employing a simulation model (MAGNET), this study examines the sustainability implications arising from the adoption of recommended daily nutrition requirements inspired by the ‘Lancet’ reference diet. To measure sustainability, changes in ‘virtual’ requirements and associated tier footprints for irrigation (blue) water, agricultural land and greenhouse gas emissions (GHG) are calculated. Assuming business-as-usual food consumption trends, between 2015 and 2050 blue water, agricultural land and emissions rise 34%, 9% and 44%, respectively, whilst corresponding increases in Sub-Saharan Africa are much higher. By 2050, the switch to the reference diet decreases agricultural land use by -8% and emissions by -9%. Global blue water and cropland requirements increase by 5%, whilst significant concomitant savings in permanent pastureland (-21%) are expected. By region, the diet switch drives rising blue water consumption in Oceania and the EU and agricultural land savings in Latin America and Oceania, accompanied by cropland increases in the EU and North Africa. The reference diet generates substantial reductions in GHG emissions, particularly in Latin America. Interestingly, Sub-Saharan Africa which abstains from the reference diet due to affordability considerations, benefits from a ‘rebound’ effect from falling meat and dairy prices. Finally, the diet shift could result in marginal per capita food expenditure rises arising from demand driven fish price, particularly in more vulnerable world regions. This estimate does not capture, however, second-round economic growth effects arising from increased labour productivity and reduced public health expenditures.