By Kathryn Milliken, Senior Climate Change Adviser, UN World Food Programme

When we talk about the impacts of climate change and events such as extreme heat on food security, many of us often jump to what this means for agricultural production. However, food security is more complex than considering production alone. Globally, we produce more than we can eat, yet we still have hunger occurring throughout the world. Up to 828 million people were considered food insecure in 2022, and the World Food Programme (WFP) estimates more than 345 million people in 79 countries face high levels of hunger this year.

A more complete definition of food security dates back to the 1996 World Summit on Food Security. It is achieved “when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life.” This speaks to four key pillars of food security: availability; accessibility; utilization; and stability. When it comes to extreme events – including extreme heat – it is (in)stability that upsets the other three pillars.

Food availability

The impacts of extreme heat on food availability are fairly well explored. Higher temperatures can severely affect agricultural yields. One study estimates that each 1^oC increase in global mean temperature could see reductions in global yields of wheat (6%), rice (3.2%), and maize (3.2%). Other research has shown reductions in crop growth. For example, maize crops in 2020 had on average nine days less for growth compared to the 30-year average between 1981-2010. Extreme heat events may also disrupt plant growth during key parts of a plant’s life cycle, such as during the July 2022 European heatwave when concerns were raised over the pollination of maize crops.

Just as human bodies are impacted by extreme heat, livestock too are vulnerable. In addition to increasing mortality, extreme heat leads to worse morbidity outcomes, including lower fertility and resilience to disease. It can also impact production of eggs, milk, and other livestock goods. The impacts of heatwaves on fisheries have been reported several times and are projected to significantly reduce fish biomass and maximum catch potential.

Severe temperature impacts during the food storage and transport processes can also see major food losses, shortened shelf life, and waste. There can be measures to help reduce these impacts – such as storing food and moving livestock in cooled indoor locations during extreme heat – but these can mean increased costs being passed onto the consumer.

Food access

Reduced food availability impacts how people – especially those with the lowest economic means – can access food to feed their families. Lower food availability, the instability of its availability, or the higher costs involved in producing it can result in increased prices that many people cannot afford. Described by some as “heatflation” the impacts of higher food costs have strongly negative outcomes for vulnerable, poor populations.

Consider the impact that the Ukraine war, taking place in a region where more than a third of the world’s wheat is grown, has had on global food prices. Just between February and March 2022, at the very beginning of the conflict, food prices are estimated to have grown 12.6% globally, although this statistic masks the devastating impact on specific countries and poorer households. Research suggests that those living in extreme poverty can spend two-thirds of their income on food (compared to approximately 25% in a high-income country). The same research shows that, based on 2022 data, each 1% increase in food prices could result in almost an additional 10 million people falling into extreme poverty.

Heatflation itself may also have direct impacts on poorer people’s incomes through loss of labor in agricultural and fisheries work. In Bangladesh alone, an extreme temperature event could lead to a loss of over 1 million jobs in the fisheries sector. In neighboring India, studies show that extreme heat in 2019 saw the loss of two weeks’ worth of the country’s potential income per capita. Temperature increases led to short-term food insecurity, which was especially prevalent among lower-income and rural families, with lower employment, increased living and healthcare costs being key factors at play.

Food utilization

The socioeconomic dimensions of inequalities point to another aspect of food security – how different individuals can absorb and use food nutrients. There are known variances in the nutritional needs of different ages and gender groups that generate greater susceptibility to malnutrition among younger children, adolescents, older people, and women who are pregnant or breastfeeding. People in extreme poverty and those suffering from illnesses are also more susceptible. While there is limited research on heat stress impacts on nutrition, these same groups are also more susceptible to heat impacts as a result of physiological and socio-economic factors. The interplay of inequalities in income, in the ability to afford adequate and nutritious food, and in being able to adopt preventative measures and access healthcare during extreme heat events can exacerbate poor nutritional and health outcomes for these groups.

Stabilizing measures

While climate change mitigation efforts continue to be put in place to reduce greenhouse gas (GHG) emissions and the resulting global heating of the planet, it is clear that the pace is not adequate to address the climate crisis. We are already observing the impacts of climate change that include an increased number of extreme heat events, and this is only predicted to worsen.

This means adaptation is necessary, with investments in known measures being key. Various climate-smart practices can be adopted in agricultural and fishery sectors, as well as other workplace environments, to help reduce the impacts of climate change on production and workforces. However, for the most vulnerable, public sector efforts are needed to address the inequalities and food insecurity that extreme heat events will only exacerbate further. Systems-level interventions are essential.

A key area for investment is social protection systems, which were successfully used to address increases in poverty and food insecurity during the COVID-19 crisis. Innovations in connecting these systems to other services are starting to grow and suggest there are ways to make social protection more climate-responsive and resilient. For example, experiences are growing in connecting early warnings to social protection systems so that governments and humanitarian organizations can anticipate and finance actions ahead of climatic events such as droughts, storms, and floods. Setting up anticipatory actions for extreme heat events could trigger additional financing to be made available in advance of these events, allowing public sector actors to more rapidly and adequately prepare and respond, thus reducing the burden on populations that tend to be most affected. Connecting health services more concretely to social protection systems and those most at risk can also help tailor support and reduce mortality and morbidity outcomes. Other measures include making energy services more accessible and affordable to vulnerable populations during extreme heat events.

Combined with other climatic impacts, extreme heat events are a threat to food security around the world. These events exacerbate negative socioeconomic outcomes, undoing development gains and worsening global hunger. It is essential that investments are made in adaptation measures that strengthen the ability of governments to address these impacts, especially on the most vulnerable.

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This article was written for Perry World House’s 2023 Global Shifts Colloquium, ‘Living with Extreme Heat: Our Shared Future,’ and made possible in part by a grant from the Carnegie Corporation of New York. The views expressed are solely the author’s and do not reflect those of Perry World House, the University of Pennsylvania, or the Carnegie Corporation of New York.