Fall 2017

By Sarabeth Lowe, MPH Ms. Lowe is a Communication Specialist at the University of Delaware Disaster Research Center. The health impacts of climate change are well established. Researchers have long documented the direct, deadly impacts of global warming, such as laborers succumbing to heat exhaustion or people drowning in flood waters. However, a growing body of research is shedding light on the various indirect and far-reaching ways climate change affects health. One of these more subtle pathways is its impact on food security.1–4 What is food security? According to the World Bank Group, food security is achieved when “all people, at all times, have physical and economic access to sufficient safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life.”6 The United States Department of Agriculture echoes this sentiment, defining food insecurity as “limited or uncertain availability of nutritionally adequate and safe foods” or the “ability to acquire acceptable foods in socially acceptable ways.”6,7 Notably, food security is multifaceted with 4 main pillars (Table 1).5,8,9 Availability is the “supply” side of food security, such as levels of production and stock. Access means having equitable, unrestricted, and regular access to food; this can be impacted by the presence of food deserts, income, socioeconomic status, and food prices. Utilization involves the biological (ie, how your body uses the nutrients in your food, supporting your overall health and wellbeing) and logistical (eg, food preparation, diet diversity, and intrahousehold distribution, etc.) facets of food utilization. The fourth pillar is stability. Food insecurity isn’t static and can change over time in response to shifts in these 3 dimensions. Some of these specific factors include weather conditions, political instability, and economic factors (eg, unemployment, rising food prices).5,8,9 It’s difficult to overstate how tightly intertwined food security and climate change are. From farm to fork, various climatic factors, including drought, sea-level rise, and higher temperatures, affect the availability, quality, and affordability of crops and livestock that support our diet.4,9–11 Furthermore, the interactions between climate change and food systems are reciprocal and cyclical, meaning that their impacts go both ways; the function of our global food system is both a major driver of climate change and increasingly vulnerable to it.8–13 For example, natural hazards and extreme weather patterns related to climate change threaten the viability of agricultural practices, supply chains, and crop and livestock resilience.9 How does climate change affect food security? Crop yield. Increasing temperatures have wide-ranging impacts on food yields and production, especially as they relate to the damage and destruction of crops. The food system contributes more than 30% of the heat-trapping gases emitted by human activities globally each year.9,14 Though previous studies have suggested that climate change may lead to crop yield increases in some temperate regions in the near term, new research shows that increasing temperatures will decrease food production in the long term.9,15–18 Results from a 2025 study published in Nature suggest that every additional degree Celsius of global warming will decrease the world’s ability to produce food by 120 calories per person per day.16,17 For context, that’s about 4.4% of daily consumption. Research also shows that climate change will decrease the production of key heritage foods and staple crops, such as corn, maize, rice, and wheat.1,8,9,11–13,18  Livestock production is another component of our food system that has a negative environmental impact. It is also one of the leading industrial contributors to greenhouse gases, accounting for an estimated 14% to 18% of global emissions.8,19–21 The distribution of land use between the livestock and farming sectors is skewed, with some estimates showing that nearly 80% of the former is used to support domestic animal farms.19–21 This imbalance only worsens the other environmental impacts of the livestock industry, including deforestation, land degradation, soil erosion, natural resource depletion, biodiversity loss, and air, water, and land pollution from animal waste and industrial farm runoff.8,9,12,20,22–26 These downstream consequences contribute to food insecurity in several indirect ways, such as food quality and water contamination. Biodiversity. Several current agricultural practices undermine biodiversity, an important pillar of achieving food security.9,26–28 According to the United Nations Food and Agriculture Organization, agriculture drives almost 90% of global deforestation, a significant driver of habitat loss and, thus, plant diversity and species extinction.28,29 At the same time, the land being cleared to grow crops often employs monoculture farming (ie, planting a single crop species, such as corn, over large areas of land for consecutive seasons).28,30 Today, only a handful of plant species, including rice, wheat, and maize, account for the vast majority of global crop production.28,31–33 This reliance on a narrow set of crops undermines our food system’s resilience and makes it extremely vulnerable to pests, pathogens, and climate extremes. An example of this is the 19th-century Irish potato famine, when reliance on a single crop with low genetic variation led to catastrophic agricultural losses due to disease.28,34–36 Biodiversity is a natural buffer against environmental changes. For example, greater plant diversity can help compensate for fluctuations in other crop yields, enhance ecosystem resilience, improve soil health, and attract more pollinators, which support and strengthen the growth of other important crops.28,36,37 A variety of animals, including insects, livestock, fish, and ruminants, also support food security. While they are important sources of meat, other animal byproducts, such as eggs and milk, also support a balanced diet and provide numerous critical micronutrients.37–39 Nutrient content. Climate change has spurred environmental conditions that have decreased the nutritional value and safety of certain crops.1–3,8,9,11–14,40–45 A groundbreaking meta-analysis published in 2025 looked at 32 nutrients across 43 different crops and found that rising levels of carbon dioxide (CO2) in the atmosphere caused a clear shift in plant composition across a wide range of species.41,42 Higher CO2 levels have increased plants’ carbon uptake, which increases the amount of carbohydrates, like sugars and starch, while decreasing the amount of protein and critical nutrients, such as iron and zinc. Put simply, each bite of food is becoming comparatively higher in calories but lower in nutrients.