Harnessing the connectivity of climate change, food systems and diets: Taking action to improve human and planetary health

Abstract

With climate change, the COVID-19 pandemic, and ongoing conflicts, food systems and the diets they produce are facing increasing fragility. In a turbulent, hot world, threatened resiliency and sustainability of food systems could make it all the more complicated to nourish a population of 9.7 billion by 2050. Climate change is having adverse impacts across food systems with more frequent and intense extreme events that will challenge food production, storage, and transport, potentially imperiling the global population's ability to access and afford healthy diets. Inadequate diets will contribute further to detrimental human and planetary health impacts. At the same time, the way food is grown, processed, packaged, and transported is having adverse impacts on the environment and finite natural resources further accelerating climate change, tropical deforestation, and biodiversity loss. This state-of-the-science iterative review covers three areas. The paper's first section presents how climate change is connected to food systems and how dietary trends and foods consumed worldwide impact human health, climate change, and environmental degradation. The second area articulates how food systems affect global dietary trends and the macro forces shaping food systems and diets. The last section highlights how specific food policies and actions related to dietary transitions can contribute to climate adaptation and mitigation responses and, at the same time, improve human and planetary health. While there is significant urgency in acting, it is also critical to move beyond the political inertia and bridge the separatism of food systems and climate change agendas that currently exists among governments and private sector actors. The window is closing and closing fast.

Keywords: Climate change; Dietary quality; Dietary transitions; Food access; Food systems.

Fig. 1

Per capita kcal/person/day shown regionally in the food supply, 1961–2019.

Fig. 2

Key components of healthy diets across regions, 1990–2018. Notes: HIC: high-income countries including Australasia, Western Europe, Canada, and the United States; FSU: former Soviet Union; Asia: includes East and Southeast Asia, Asia-Pacific, and Oceania; SAARC: South Asian Association for Regional Cooperation; LAC: Latin America and the Caribbean; MENA: Middle-East and North Africa; SSA: Sub-Saharan Africa; MUFA: monounsaturated fatty acids; Omega6: total omega-6 fat. Healthy diet components from (WHO, 2018): at least 400 g/day of fruits and vegetables (target line); 25 g/day of dietary fiber (shaded area); < 10% total daily energy from free sugars (shaded area), but < 5% of daily energy for additional health benefits (the figures depict added sugars, which do not consider naturally occurring sugars in honey, fruit juice, or concentrate - thus added sugars will be lower than free sugars); < 5 g/day of salt (shaded area)(converted from sodium in a ratio of 1000 mg sodium per 2.5 g of salt); < 30% of total daily energy from fats and < 10% energy from saturated fats (target lines). The WHO recommends the intake of whole grains, nuts, and legumes as part of a healthy diet but does not specify quantities. Recommended intakes from EAT-Lancet Commission were used to establish a quantitative target of 250 g/day (target line) for these three foods, consisting of 25 g of nuts, 100 g of legumes, and 125 g of whole grains (Willett et al., 2019).

Fig. 3

Sales of ultra-processed food (g/capita) categories, 2006–2024. Notes: Source data were converted from kilograms or liters/capita/year to grams or milliliters/capita/day to facilitate interpretation.

Fig. 4

Change in demand for animal-source foods, 1990-2020 (grams/person/day). Notes: All regional definitions use UN definitions. Source data were converted from change in kilograms/capita/year to change in grams/capita/day to facilitate interpretation..

Fig. 5

Change in consumption of dairy products regionally, 1990-2018. Notes: HIC: high-income countries including Australasia, Western Europe, Canada, and the United States; FSU: former Soviet Union; Asia: includes East and Southeast Asia, Asia-Pacific, and Oceania; SAARC: South Asian Association for Regional Cooperation; LAC: Latin America and the Caribbean; MENA: Middle-East and North Africa; SSA: Sub-Saharan Africa..

Fig. 6

Prevalence of deficiencies in one or more of three core micronutrients, world, and different regions, 2003 – 2019. Notes: This analysis estimates the prevalence of deficiency in at least one of three micronutrients for preschool-aged children (iron, zinc, and vitamin A) and non-pregnant women of reproductive age (iron, zinc, and folate), globally, in high-income countries (HIC), and seven regions using 24 nationally representative surveys done between 2003 and 2019.

Fig. 7

Deaths attributable to dietary risk factors by cause of death for risks related to dietary composition and weight levels, 2018. Notes: The combined risk is less than the sum of individual risks because individuals can be exposed to multiple risks, but mortality is ascribed to one risk and cause.

Fig. 8

Pressure of different commodities of the food system on environmental factors as a percentage of total pressure. Notes: The footprints consider all food production, including inputs such as fertilizers and feed, transport, and processing, e.g., of oil seeds to oils and sugar crops to sugars. The displayed total pressure is in the units stated for each environmental domain and rounded to the nearest ten units.

Fig. 9

Percent of the population who cannot afford a healthy diet at 52% of income. Notes: Proportion of the population whose food budget is below the cost of a healthy diet. The food budget is defined as 52% of household income, based on the average share of income that households in low-income countries spend on food. Income data are provided by the World Bank's Poverty and Inequality Platform. A value of zero indicates a null or a small number rounded down at the current precision level. Data are currently available for 2017, 2018, 2019, and 2020. LBR = Liberia; COD = Democratic Republic of the Congo; ETH = Ethiopia; NPL = Nepal; PAK = Pakistan; IND = India; IDN = Indonesia; HND = Honduras; LKA = Sri Lanka; SEN = Senegal; MEX = Mexico; IRN = Iran; BRA = Brazil; CHN = China; RUS = Russia; ITA = Italy; JPN = Japan; USA = United States of America.

Fig. 10

Cost of animal-sourced foods relative to the starchy staples in a least-cost healthy diet. Notes: The map shows the cost of the least expensive animal-source foods as a multiple of the least expensive starchy staples to meet intake levels recommended in food-based dietary guidelines.A ratio greater than 1 indicates a high-cost food group. A ratio of less than 1 indicates the food group costs less than the cost of starchy staples. Data are available for 2017.

Fig. 11

The double burden of malnutrition. Notes: The double burden of malnutrition is defined as a high prevalence of undernutrition and overweight in at least one population group. A high prevalence of undernutrition is defined as the prevalence of wasting > 15% or stunting > 30% in children under 5 years or the prevalence of being underweight in women > 20%. A high prevalence of overweight is defined as adult or child overweight prevalence greater than 20%, 30%, or 40%.

Fig. 12

Modeled projections of global food production, diet, and food waste changes in 2050 using two different scenarios. Notes: These results present are estimated from a particular modeling exercise of the EAT-Lancet Commission with particular scenario assumptions. See additional methodological details from the source.Blue bars show a business-as-usual scenario in 2050 of current food production practices and maintaining current levels of food loss and waste. Green bars show a scenario of how food production would need to change if the world were to consume the EAT-Lancet planetary health diet and cut food loss and waste in half..

Fig. 13

The mitigation potential of food system actions. Notes: Each bar shows a food system change that leads to emission reductions equivalent to 1.5 °C. The blue bars are business-as-usual emissions. The yellow bars are food production changes that improve efficiency in which GHG emissions are reduced by 40% per unit of food produced and increase yields by 14% above the current maximum yields. The green bars indicate changes to dietary patterns in which a plant-dominant diet and consumption of 2100 daily kilocalories per person are maintained. The brown bar signifies a reduction in food loss and waste. The gray bar shows the combined changes of all five strategies, which gets closer to the 1.5 °C goal.

Fig. 14

Mitigation and adaptation potential of food system responses. Notes: The blue and gray colors indicate different levels of synergy between mitigation and adaptation to climate change (from none to very high) associated with each food system response.