Differentiated responsibilities of US citizens in the country's sustainable dietary transition

Abstract

If widely adopted, the 'planetary health diet' (PHD), proposed by the EAT-Lancet Commission, would help to meet ambitious sustainability goals currently jeopardised by excessive and resource intensive food demand. To date, convergence of nations to the PHD has been assessed using average food consumption patterns, overlooking the influence of different consumers within this context. Using self-reported dietary intake data from a snapshot survey of the US we reveal the differentiated responsibilities of US citizens within the country's adoption of the PHD otherwise hidden by use of country averaged dietary intake data. We show how such a granular analysis of food consumption patterns is critical to identify levers in the sustainable food transition of nations. By combining 7418 individual food intake reports from a representative cross section of the United States (US) with commodity-level impact data we estimate the overshoot of US dietary patterns in relation to the PHD and their impacts across the climate, water and land system. The net environmental impacts of PHD adoption across the US population are quantified based on realistic dietary shifts. We estimate that US overshoot of the PHD is responsible for 70% of the US dietary greenhouse gas (GHG) footprint. However, over 60% of this burden could be eliminated by just 10% of the US population following the PHD. Although we estimate PHD adoption will more than half the US dietary GHG footprint and land footprint, we find it may have unintended consequences on water demand due to increased tree nut consumption. Across almost all food categories, we show that the food choices of the top tier of consumers in the US create, and must bridge the PHD gap. As such, actions by these consumers will be of major consequences to the speed and direction of the country's sustainable dietary transition. To avoid environmental trade-offs, dietary policies must be scrutinised across multiple sustainability criteria.