The outputs of agriculture – plants and animals, are critical determinants of human health, both through the nutrition they provide and in some cases, the diseases they transmit. 

When agricultural systems are negatively impacted by weather, climate change and environmental degradation, food security is compromised and human health can be impacted in several ways:

• All forms of malnutrition, including:
  • undernutrition, such as stunting and wasting;
  • micronutrient deficiencies; and
  • overweight and obesity 
• Diet-related non-communicable diseases, such as hypertension, high blood fats and blood sugar, cardiovascular diseases, Type 2 diabetes, and some cancers
• Exposure to food-borne diseases
• Exposure to air pollutants emitted during food production and transportation

The IPCC estimates that 21–37% of total greenhouse gas (GHG) emissions are attributable to agriculture. This estimate includes emissions of 9–14% from crop and livestock activities within the farm, 5–14% from land use and land-use change including deforestation and peatland degradation, and 5–10% from supply chain activities, as well as GHG emissions from food loss and waste. 

Without intervention, total GHG emissions are likely to increase by about 30–40% by 2050, due to increasing demand based on population, income growth and dietary change. 

Climate change is already affecting food security, through increased temperatures, changing precipitation patterns, and greater frequency of some extreme events impairing food availability, access, use and the stability of these over time. 

The increasing frequency of heatwaves resulted in an additional 98 million people reporting moderate to medium food insecurity in the 103 countries analysed in 2020, compared to the 1981-2010 average. This threatens to compound the impacts on food insecurity of the COVID-19 pandemic, and the energy and cost of living crises.^{1 1}2022 Global Report of the Lancet CountdownX

Experts have high confidence that food security will be increasingly affected by projected future climate change.

Availability

Globally, overall food production and agriculture is expected to be negatively impacted by climate change, including reduced yields of major crops such as rice, wheat, and maize. Climate change is also likely to reduce the productivity of fisheries in some regions; a major source of protein for some populations.^{2 2}AR5 Porter et. al. 2014, Myers et al. 2017; Savage et al. 2020X

Vulnerability of pastoral systems to climate change is also high. Pastoralism is practiced in more than 75% of countries, by between 200 and 500 million people. Impacts in pastoral systems in Africa include lower pasture and animal productivity, damaged reproductive function, and biodiversity loss. Pastoral system vulnerability is exacerbated by non-climate factors (land tenure, sedentarisation, changes in traditional institutions, invasive species, lack of markets, and conflicts). 

With climate change, distributions of pests and diseases will also change, affecting production in many regions. Given increasing extreme events and interconnectedness, the risks of disruptions to the food system are growing.

Access

As a result of climate change, rising food prices will impact food security. The IPCC predicts a 1–29% cereal price increase in 2050 due to climate change, which would impact consumers globally. Low-income consumers and countries with high food imports, such as small island developing states, are particularly at risk, with models projecting increases of 1–183 million additional people at risk of hunger. 

Use / Nutrition

While increased CO2 is projected to be beneficial for crop productivity at lower temperature increases, it is also projected to lower nutritional quality. For example, wheat grown at 546–586 ppm CO2 has 5.9–12.7% less protein, 3.7–6.5% less zinc, and 5.2–7.5% less iron. 

Declines in the availability of food, limits on small-scale agricultural production due to less favourable growing conditions and unpredictable seasons, and scarcity of water or labour resulting from climate change, could adversely affect nutrition. Many impacts of climate change on nutrition are likely to be felt indirectly, through its effects on income and livelihoods and the capacity to access a diversity of food.

GHG emissions can be reduced and agricultural system resilience enhanced by combining supply-side actions such as efficient production, transportation, and processing, with demand-side interventions such as modification of food choices and the reduction of food loss and waste.

Protecting local food supplies, assets and livelihoods against the effects of increasing weather and climate variability and increased frequency and intensity of extreme events can be achieved through: 

• general risk management;
• management of risks specific to different ecosystems (marine, coastal, inland water and floodplain, forest, dryland, island, mountain, polar, cultivated);
• research and dissemination of crop varieties and breeds adapted to changing climatic conditions; and;
• introducing tree crops to provide food, fodder and energy and enhance cash incomes.