Analysis and valuation of the health and climate change cobenefits of dietary change

The study finds that changes towards more plant-based diets in line with the WHO’s global dietary guidelines could avert 5-8m deaths per year by 2050 (representing  a 6-10% reduction in global mortality). The monetized value of such health improvements could be comparable with, and possibly larger than, the environmental benefits of the avoided damages from climate change. Adopting global dietary guidelines would cut food-related emissions by 29%, but that the reduction would rise to 63% if everyone went vegetarian and to 70% if everyone went vegan.  In total, it is estimated that up to $31 trillion could be saved, through reductions in damaging environmental impacts, healthcare costs, lost work time, and premature deaths.  

The authors of the paper state that three quarters of all benefits of changed diets occur in developing countries, but measured per capita, the impacts of dietary change would be greatest in developed countries. This is partly explained by the fact that people in wealthy countries eat about twice as much meat as people in developing countries.

For the health analysis, the authors used a comparative risk assessment model to estimate age and region-specific mortality associated with 4 changes in diet (less meat, more fruit and vegetables, lower energy intakes). For the environmental analysis, they linked regional and scenario specific diet to GHG emissions using a meta-analysis of life cycle studies as undertaken by Tilman and Clark. Finally, for the economic analysis, the monetized values (in USD trillions) were attributed to changes in GHG emissions by using estimates of the social costs of carbon as well and also quantified in economic terms the economic consequences diet related changes in illness and premature death. For the latter the authors used two complementary approaches to assess the economic value of the diet related health impacts. First, “cost-of-illness” techniques were used to calculate the direct health-care costs and the indirect costs of informal care and lost work days that are associated with deaths from specific diet related diseases. Second, they used region-specific data on the willingness of individuals to pay for incremental mortality reductions (the “value of statistical life”). The authors stress that the economic analysis is preliminary and requires further improvement.  The economic analysis does not consider the knock on effects of dietary changes on jobs and livelihoods.

Four diets were modelled against a reference scenario.  The reference scenario is based on projections from the Food and Agriculture Organization of the United Nations (FAO), with adjustments to take into account the fraction of nonedible and wasted food. The second scenario (healthy global diets) assumes the implementation of global dietary guidelines on healthy eating and that people consume just enough calories to maintain a healthy body weight.  The last two scenarios also assume a healthy energy intake but based on observed vegetarian diets, either including eggs and dairy (lacto-ovo vegetarian) or completely plant-based. The three nonreference scenarios were not intended to be realizable dietary outcomes on a global level but are designed to explore the range of possible environmental and health outcomes of progressively excluding more animal-sourced foods from human diets. Note that when considering the health consequences of changes in diets, the authors do not consider any impacts arising from changes in micronutrient status.

When they analysed the environmental and health impacts of these dietary scenarios in 2050 they found that:

• More plant based diets could reduce global mortality by 6-10% and could reduce food related greenhouse gas emissions by 29-70% in 2050 compared to a baseline scenario.
• The impacts of lower meat diets, and increased plant-based diets had impacts that varied greatly between regions: the largest absolute environmental and health benefits were due to dietary shifts in developing countries, but in developed countries, the benefit was greater per capita.
• The economic benefit of health improvements associated with dietary change could be comparable to, or even exceed the value of environmental benefits. This calculation is greatly affected by which methods are used.
• The overall economic benefits of improving diets could be 1-31 trillion USD (0.4-13% of global GDP) in 2050.

Abstract

What we eat greatly influences our personal health and the environment we all share. Recent analyses have highlighted the likely dual health and environmental benefits of reducing the fraction of animal-sourced foods in our diets. Here, we couple for the first time, to our knowledge, a region-specific global health model based on dietary and weight-related risk factors with emissions accounting and economic valuation modules to quantify the linked health and environmental consequences of dietary changes. We find that the impacts of dietary changes toward less meat and more plant-based diets vary greatly among regions. The largest absolute environmental and health benefits result from diet shifts in developing countries whereas Western high-income and middle-income countries gain most in per capita terms. Transitioning toward more plant-based diets that are in line with standard dietary guidelines could reduce global mortality by 6–10% and food-related greenhouse gas emissions by 29–70% compared with a reference scenario in 2050. We find that the monetized value of the improvements in health would be comparable with, or exceed, the value of the environmental benefits although the exact valuation method used considerably affects the estimated amounts. Overall, we estimate the economic benefits of improving diets to be 1–31 trillion US dollars, which is equivalent to 0.4–13% of global gross domestic product (GDP) in 2050. However, significant changes in the global food system would be necessary for regional diets to match the dietary patterns studied here.

Citation

Springmann, M., Godfray, H. J. C.,  Rayner, M., Scarborough, P. (2016), Analysis and valuation of the health and climate change cobenefits of dietary change, PNAS, vol. 113 no. 15 4146–4151, doi: 10.1073/pnas.1523119113

Read the full paper here.  You will find quite extensive news media coverage about this article: see for example The Conversation here, Civil Eats here and Grist here.

You can also find further resources related to consumption and diets, dietary guidelines, global health, sustainable healthy diets, vegetarianism/veganism in our research library.