Humans as Omnivores

1. Humans are omnivores, meaning they naturally consume foods from multiple biological kingdoms including fungi, plants, meat, and fish.
2. Omnivory allows dietary flexibility, meaning humans can shift their consumption based on ecological, cultural, and economic factors.
3. Human diets vary widely worldwide, shaped by cultural traditions, religious rules, resource availability, affordability, and ecosystem productivity.

Trophic Levels and Sustainability

1. Diets lower in trophic levels are more sustainable, because less energy is lost between food chain steps.
2. Plants occupy trophic level 1, meaning they contain energy directly from photosynthesis.
3. Livestock occupy higher trophic levels, meaning producing meat requires more land, water, and feed inputs.
4. Energy transfer follows the second law of thermodynamics, where approximately 90 percent of energy is lost at each trophic level.
5. Eating plant-based foods bypasses energy losses that occur when plants are first fed to animals.

Comparing Crop Production and Livestock Production

1. Efficiency of Food Yield per Unit Land

1. Crops provide a higher yield per unit of land than livestock, because plant biomass can be consumed directly rather than being converted to animal biomass.
2. Producing livestock requires additional land to grow animal feed, significantly increasing the land footprint.
3. Livestock farming also requires grazing land, which takes up large global land areas that could otherwise grow food for direct human consumption.
4. Intensive livestock farming concentrates animals indoors at high densities, increasing disease risks and environmental impacts.

2. Efficiency of Resource Use (Water, Land, Energy)

1. Beef, lamb, prawns, and cheese have extremely high water and carbon footprints, as shown in global emission data.
2. Livestock require energy for movement, body heat, and metabolism, so feed-to-meat conversion efficiency is low.
3. Producing 1 kilogram of beef requires producing approximately 10 kilograms of plant feed, causing massive energy inefficiency.

Sustainability Benefits of Plant-Based Diets

1. Lower environmental impact

1. Plant-based diets reduce greenhouse gas emissions, because livestock (especially ruminants like cattle) produce methane.
2. Eating more plant-based foods reduces the demand for resource-intensive livestock farming.
3. Shifting to lower-trophic-level foods frees up large areas of land, which could be rewilded, reforested, or used to grow more crops directly for humans.
4. One global study estimated that a complete global shift to a vegan diet could reduce agricultural land use by up to 75 percent, an area roughly the size of North America plus Brazil.

2. Increased efficiency in global food distribution

1. Plant-based diets increase the total food available because less land is wasted producing animal feed.
2. A larger percentage of Earth's net primary productivity becomes available for human consumption.
3. More efficient land use reduces pressure for deforestation, protecting biodiversity and ecosystem services.

Ethical Considerations (HL only)

1. Plant-based diets raise important ethical questions, including animal rights, fairness in resource distribution, and minimizing environmental harm.
2. Religious, cultural, and environmental value systems influence dietary choices, making sustainability a complex ethical issue.
3. Animal welfare concerns, ecocentric values, and environmental ethics all support reducing meat consumption.

Global Strategies for Sustainable Food Supply

Why Global Food Systems Must Become More Sustainable

1. Global agriculture produces enough food to feed the world, yet distribution inequalities lead to hunger in some regions and waste in others.
2. At least one-third of all food produced is wasted, making food waste one of the biggest barriers to sustainability.
3. Modern agriculture contributes heavily to climate change, via nitrous oxide from soils, methane from livestock, and emissions from fertilizer production.
4. Sustainable food systems aim to reduce environmental damage while maintaining or increasing yield without expanding farmland.

Strategies to Reduce Demand and Food Waste

1. Reducing Dietary Demand for Unsustainable Foods

1. Reducing consumption of resource-intensive foods such as beef decreases pressure on land, water, and the climate.
2. Plant-based meat substitutes provide high-protein alternatives that reduce reliance on livestock.
3. Cultural, economic, and ethical factors influence dietary choices, making policy interventions necessary.
4. Governments can shift demand using taxes on unsustainable products or subsidies for sustainable ones.
5. Reducing demand does not automatically guarantee redistribution, because food markets respond to economic incentives, not ethics.

2. Reducing Food Waste

1. Food waste occurs at every stage of the supply chain, from storage and transport to retail and households.
2. One-third of global food is wasted, representing lost resources, emissions, and money.
3. SDG 12.3 aims to reduce food waste by 50 percent by 2030.
4. Extending food shelf life reduces consumer waste, requiring improved packaging, refrigeration, and atmospheric control during transport.
5. Redistribution programs address inequality, directing unsold food to communities facing shortages.

Strategies to Reduce Greenhouse Gas Emissions from Food Production

1. Reducing Nitrous Oxide Emissions

1. Nitrous oxide emissions arise largely from denitrifying bacteria in nitrogen-enriched soils.
2. Applying excessive nitrogen fertilizers increases nitrification and denitrification, raising N₂O emissions.
3. Reducing fertilizer use and improving timing can limit N₂O release.
4. Alternatives such as organic fertilizers, cover crops, and mixed cropping reduce the need for synthetic fertilizers.

2. Reducing Methane Emissions from Rice Cultivation

1. Flooded rice paddies create anaerobic conditions, producing methane through anaerobic decomposition.
2. Rice accounts for 10 percent of global arable land and 10 percent of global methane emissions.
3. Alternate wetting and drying (AWD) lowers methane emissions by allowing periodic aeration.
4. Furrow irrigation floods only narrow channels, maintaining rice growth while reducing methane production.
5. Removing crop residues before flooding reduces anaerobic decomposition.

3. Reducing Methane from Ruminants

1. Ruminants (e.g., cattle) emit methane due to microbial fermentation in their rumen.
2. Diet modifications using starch-rich feed reduce methane emissions.
3. Specific microbial additives or seaweed-based supplements can change rumen microbial composition.
4. Research is ongoing into methane-reducing vaccines and selective breeding.

Increasing Productivity Without Expanding Land Use

1. Genetic Modification (GM)

• Genetic engineering increases yield, improves nutritional value, and reduces pest losses.
• GM reduces pesticide use, enhances resilience, and extends shelf life, lowering waste.

2. In-field Solar-Powered Fertilizer Production

1. New technologies produce nitrogen fertilizers on the farm using solar energy and catalysts.
2. This eliminates fossil fuel dependence, reduces transport emissions, and prevents over-application.
3. Farmers can generate only the amount needed, improving sustainability and reducing N₂O emissions.

3. Extending Shelf Life

1. Longer shelf lives reduce retail and household waste through improved refrigeration, packaging, and atmosphere control.
2. Controlling humidity and temperature reduces spoilage from fungi and bacteria.

Food Waste and Distribution Inefficiencies

1. Global agriculture produces enough food for eight billion people, but inequitable distribution and waste result in hunger.
2. Some regions have food surpluses while others face chronic shortages, highlighting infrastructure and economic barriers.
3. Improved distribution networks, cold storage, and logistics reduce spoilage and increase availability.

Food Security

1. Food security means all individuals have physical and economic access to sufficient, safe, and nutritious food at all times.
2. Food security includes food availability, access, utilization, and stability, as defined by the FAO.
3. Food insecurity affects physical health, economic development, and political stability.

The Four Dimensions of Food Security

1. Availability

1. Availability refers to whether enough food is physically produced and supplied.
2. National food availability depends on domestic production and imports.

2. Access

1. Access refers to economic ability to purchase food, influenced by income, food prices, inflation, and cost of living.
2. Physical access includes infrastructure, markets, and transportation systems.

3. Utilization

1. Utilization concerns how the body uses food, influenced by sanitation, healthcare, safe water, and nutritional knowledge.
2. Poor utilization can lead to malnutrition even where food is available.

4. Stability

1. Food access must be reliable over time, without disruption from climate shocks, economic crises, political conflict, or disasters.
2. Long-term stability depends on resilient agricultural systems and social safety nets.

Global Patterns of Food Security

1. Developed Regions

1. Developed regions generally experience high food security, supported by stable economies and strong infrastructure.
2. Social safety nets and efficient distribution systems reduce the risk of hunger.
3. North America and Western Europe are common examples.

2. Developing Regions

1. Developing regions experience varied and often lower food security, due to economic inequality, political instability, and limited infrastructure.
2. Food insecurity is common in Sub-Saharan Africa, South Asia, and parts of Latin America.
3. Dependence on food imports makes countries vulnerable to price fluctuations and trade disruptions.

Factors Affecting Food Security

1. Economic Factors: Income levels, employment opportunities, and food prices determine purchasing power, influencing household food access.
2. Environmental Factors: Climate change, droughts, soils degradation, and natural disasters affect food production, reducing availability.
3. Social and Political Factors: Corruption, conflict, inequality, and policy failures disrupt distribution systems, worsening food insecurity.