Inés Azaiez, Programme Manager Nutrition, Global Development Area

“It is clear that decisions we are making every day—how we heat our homes, what we eat, how we move around, what we choose to purchase—are making our food less nutritious, and imperiling the health of other populations and future generations” (Sam Myers, principal scientist at the Harvard School).

Climate change is one of the biggest challenges facing both our, and future, generations. The climate crisis is accelerating faster than previously anticipated, with various models predicting alarming to catastrophic impacts of the climate crisis on humans and the environment. In a world where undernutrition is declining very slowly and overnutrition is increasing rapidly, climate change will have multifaceted and severe effects on nutritional status and therefore survival, health and development outcomes. Climate change and nutrition have overlapping agendas and enhanced collaboration could generate a common agenda for both communities.

According to the FAO [1], it is estimated that between 691 and 783 million people in the world faced hunger in 2022 while more than 3.1 billion people in the world – or 42% – were unable to afford a healthy diet in 2021.

Currently, an estimated 148.1 million children under five years of age (22.3%) were stunted, 45 million (6.8%) were wasted, and 37 million (5.6%) were overweight.

The last report reports published by The Intergovernmental Panel on Climate Change [2] confirm that  Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface temperature reaching 1.1°C above 1850–1900 in 2011–2020. Global greenhouse gas emissions have continued to increase over 2010–2019, with unequal historical and ongoing contributions arising from unsustainable energy use, land use and land-use change, lifestyles and patterns of consumption and production across regions, between and within countries, and between individuals (high confidence).

Human-caused climate change is already affecting many weather and climate extremes in every region across the globe. This has led to widespread adverse impacts on food and water security, human health and on economies and society and related losses and damages to nature and people. Vulnerable communities who have historically contributed the least to current climate change are disproportionately affected.

Climate change and undernutrition

Climate change exacerbates undernutrition through three causal pathways related to (or though combined effects on) food security, care practices and health. Quantifying the effects of climate change on undernutrition is a complex exercise, due to the multiple causal pathways leading to undernutrition [3].

An increasingly large body of evidence indicates that undernutrition in all populations, particularly vulnerable populations (such as women, infants, children and adolescents), is likely to be magnified by climate change, without effective countermeasures. The impacts of climate variability and change on nutrition occur indirectly, by exacerbating existing threats to “food, care and health”. The mechanisms through which climate change jeopardizes “food, care and health”-related determinants of nutrition, are myriad. The arrows on the left in Figure 1 highlight that climate variability and change can also affect the entire food system at multiple levels (immediate, underlying and basic).

Figure 1: Conceptual framework: climate and nutrition security: WHO, 2021 [4].

The ramifications of climate change on nutritional outcomes in the future are estimated to be significant, and the exacerbation of current threats to food and nutritional security will only make it harder and more expensive to reduce undernutrition in the coming decades. Furthermore, undernutrition undermines the health and coping mechanisms of vulnerable populations, and lessens their capacities to be resilient and adapt to other consequences of climate change. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) concludes with high confidence “that climate change will have a substantial negative impact on (i) per capita calorie availability; (ii) childhood undernutrition, particularly stunting; and (iii) undernutrition-related child deaths and DALYs (disability adjusted life years) lost in developing countries” [4].

Climate change worsens unsustainable food systems by affecting all aspects of food security: availability, access, utilisation and stability, through diverse impacts on crops, pests, diseases, weeds, pollination, forests, livestock, and aquatic food sources.

Food availability will be directly impacted by increased climate variability and long term climate change. Longer term warming, increased atmospheric carbon dioxide (CO2), and altered precipitation patterns will have wide sweeping impacts on agricultural production and livelihoods assets and increase irrigation water requirements.

This will increase heat and water stress in areas already under pressure, while increasing pests and diseases in crops and livestock, thus decreasing yields and changing the suitability of areas for food production. In southern Madagascar, four years of successive droughts have wiped out harvests and hampered access to food and the area is on the brink of experiencing the world’s first “climate change famine”, according to the UN [5].

The IPCC [6] has concluded that risks of foodborne and waterborne disease and vector-borne disease will increase, further impacting nutrition as a consequence of warmer temperatures, extreme weather, and shifting precipitation patterns. In 2019, unusual weather conditions exacerbated by climate change created conditions conducive to a desert locust outbreak which destroyed food and vegetation and jeopardised food security across Africa, the Middle East and South Asia. Recent evidence from Tanzania also identifies the association between reduced cereal (maize) yields and maternal malnutrition during pregnancy as key pathways linking heat shocks to agricultural production and subsequent child growth. Increased ocean acidification and other adverse changes to marine ecology will also affect households who rely on fish to support their livelihoods and nutrition. For example, one study has estimated a 92% reduction in coral reef habitats by 2100 due to ocean warming and acidification [7].

There is evidence that rising carbon dioxide levels from human activity may be reducing nutrient levels (protein, iron and zinc) in plant foods, particularly cereals and legumes.

These are all essential nutrients for people’s health and represent major risks to people’s health in developing nations where deficiencies in zinc, iron and protein lead to major burdens of disease. These diseases range from maternal mortality around childbirth to problems with cognitive development in children. Cereal crops are the main source of protein and micronutrients in many low-income countries.

Climate change is also one of the key drivers of biodiversity loss in agriculture, which in turn reduces the ability of the food system to respond to shocks and stresses, including further climate change.

Increased heat and water stress is also expected to increase the incidence of foodborne pathogens and mycotoxins during food storage, processing and transportation. There is a general lack of governance and policies around food safety, while the risks of food safety and increasing food waste in rural communities are especially acute as retail infrastructure and cold storage are often basic and access to water may be restricted. In addition, the various climate-related changes impacting food safety – including human, animal and vector behaviours, and changing pathogen, organism and pest survival, growth and transmission behaviours– are more likely to occur in countries where food monitoring and surveillance systems are less robust. Thus, poor detection of environmental and chemical contamination further increases the risk to public health and nutrition through the acute and chronic exposure to contaminants [8].

Access to food may reduce through climate change impacts increasing the price of food. A key determinant for access is the price of food which strongly reacts to fluctuations in global production following extreme climate-related events and longer-term reduced crop yields resulting from climate change. Resource-poor households commonly prioritize calorie-rich but nutrient-poor foods as an adaptation strategy to reduced food availability and increased food prices. In the long term, the recurrent and intense nature of such events can increasingly destabilize regional and local food systems, with a potential to trigger food crises, acute malnutrition, and even famines [4].

Furthermore according to ICCP, Climate change is contributing to humanitarian crises where climate hazards interact with high vulnerability (high confidence). Climate and weather extremes are increasingly driving displacement in all regions. Flood and drought-related acute food insecurity and malnutrition have increased in Africa and Central and South America. While non-climatic factors are the dominant drivers of existing intrastate violent conflicts, in some assessed regions extreme weather and climate events have had a small, adverse impact on their length, severity or frequency, but the statistical association is weak. Through displacement and involuntary migration from extreme weather and climate events, climate change has generated and perpetuated vulnerability [2].

Climate change, obesity and DR-NCDs

There is limited but emerging evidence that climate change will adversely affect the risk of overweight and obesity and, as a consequence, diet-related non-communicable diseases (DR-NCDs). While severe food insecurity and hunger are associated with lower obesity prevalence, mild to moderate food insecurity is paradoxically associated with higher obesity prevalence, particularly in contexts where high-energy, commercially processed foods are available at low cost. Increasing temperatures are associated with less physical activity in many parts of the world, particularly among urban populations, while price instability of fresh foods can reinforce dependency on highly processed foods, especially in the context of aggressive marketing. Climate change-induced migration, the majority of which is likely to be rural-urban migration, is predicted to become increasingly driven by food insecurity. Urbanisation has been associated with an increased risk of overweight and obesity through a combination of greater availability of energy dense, processed foods in combination with mass media marketing, and less leisure and work-related physical activity. Furthermore, in humanitarian settings, food assistance provided during an emergency response, such as to climate-induced natural disasters, can weaken long-term food and nutrition security; for example, low-quality, imported foods may persist in the local diet long after the humanitarian response has concluded.

It is likely that these and other pathways leading to climate change-induced food and nutrition insecurity will exacerbate already-changing dietary patterns, which tend to be increasingly comprised of high-energy and low-nutrient dense imported and processed foods [8].

The world’s poorest are paying the highest price

While climate change is global, impacts are local and regional, and vulnerability varies widely across communities, countries, and regions  [9].

The injustice of climate change is that the people who are suffering the most—the world’s poorest—are also the ones who did the least to contribute to the problem.

In fact, recent data showed that the poorest people already suffering from the highest rates of undernutrition will be the most vulnerable to climate change (figure 2).

Figure 2 : Map of climate vulnerability. It shows the places that will be hit hardest by global warming, including extreme weather, drought, and sea level rise [10].

Vulnerability will increase with climate change: exposure to climate change-related effects and dependence on climate-sensitive resources will rise, as adaptive capacity decreases. They rely on small-scale rain-fed farming systems and agricultural labour as their main source of food and income, making them highly dependent on climate-sensitive natural resources. Climate change is increasingly and simultaneously eroding their livelihoods assets and access to natural resources and services, while at the same time eroding their capacity to cope with climate-related crises, and adopt sustainable solutions to climate change. The hungry poor, especially women and children, are already the main victims of the changing climat. Indeed, when facing a disaster, people have no choice but to resort to negative coping strategies (reduction of food intake, sale of productive assets etc.) that hinder their resilience, increase their vulnerability to climate threats, and exacerbate their food and nutritional security (figure3). Undernutrition undermines the ability and capacity of vulnerable populations to implement resilient climate coping strategies [11].

Conclusion & way forward

Climate change is affecting malnutrition rates around the world through multiple channels. In regions experiencing historic levels of drought, like the Horn of Africa, millions are suffering from near-famine. Elsewhere, climate change is increasing the incidence of diseases that contribute to malnutrition. Climate change can also diminish the nutritional value of crops, and climate change can affect families’ livelihoods, reducing their incomes and making nutritious foods less affordable.

As appointed by EU experts 14, To tackle the risk of severe and frequent climate related disasters, greater science – policy interface based on improved knowledge, stronger evidence and a greater focus on Disaster Risk Reduction and Climate Change Adaptation are essential.

Adaptation, in response to current climate change, is reducing climate risks and vulnerability mostly via adjustment of existing systems. Many adaptation options exist and are used to help manage projected climate change impacts, but their implementation depends upon the capacity and effectiveness of governance and decision-making processes.

Timely and well-designed adaptation actions have the possibility to avoid these dramatic issues by mitigating theimpacts of climate change on the most vulnerable through preparedness, risk reduction, both applied to the livelihoods and the organization of society.

Effective adaptation options, together with supportive public policies enhance food availability and stability and reduce climate risk for food systems while increasing their sustainability. Effective options include cultivar improvements, agroforestry, community-based adaptation, farm and landscape diversification, and urban agriculture. Institutional feasibility, adaptation limits of crops and cost effectiveness also influence the effectiveness of the adaptation options. Agroecological principles and practices, ecosystem-based management in fisheries and aquaculture, and other approaches that work with natural processes support food security, nutrition, health and well-being, livelihoods and biodiversity, sustainability and ecosystem services.


[1] FAO, IFAD, UNICEF, WFP & WHO, 2023. The state of food security and nutrition in the world :Urbanization, agrifood systems transformation and healthy diets across the rural–urban continuum.

[2] IPCC, 2022. Climate Change 2022: Impacts, Adaptation and Vulnerability Working Group II Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

[3] Word Food Programme, 2021. Climate impacts on food security and nutrition.

[4] World Health Organization, 2021. Technical series on adapting to Climate Sensitive Health Impacts – Undernutrition.

[5] BBC. (2021). Madagascar on the brink of climate change-induced famine.

[6] IPCC. (2014). Climate change 2014: Impacts, adaptation, and vulnerability. Working Group II contribution to the fifth assessment report of the Intergovernmental Panel on Climate Change. New York; Cambridge University Press.

[7] Speers, A.E., Besedin, E.Y., Palardy, J.E., & Moore, C.,2016. Impacts of climate change and ocean acidification on coral reef fisheries: An integrated ecological-economic model. Ecological Economics, 128, 33–43.

[8] Emergency Nutrition Network, 2021 Nutrition and climate change: Current state of play: Scoping review.

[9] Archibald, C.L., Butt, N. Using Google search data to inform global climate change adaptation policy. Climatic Change 150, 447–456 (2018).

[10] Williams J., 2018. Two maps: climate responsibility and climate vulnerability.

[11] ACF-INTERNATIONAL, 2014. Who cares about the impact of climate change on hunger and malnutrition? A plea to the international community to ensure food and nutrition security for the most vulnerable in a changing climate.

[12] European Union EU: