IB Environmental systems and societies 5.2G Sustainability of Different Diets Notes

Sustainable Diets: What You Eat Matters More Than Where It Comes From

1. The sustainability of a diet depends on how food is produced, processed, transported and consumed, making it an environmental, social and economic issue at once.
2. Key factors include supply chain length, farming techniques, food miles, and shifts in eating habits.
3. A sustainable diet aims to meet nutritional needs while limiting harm to ecosystems, climate, biodiversity and resources.

Supply Chains: More Intermediaries Mean More Impact

1. A supply chain covers every stage from production to processing, packaging, transport, retail and consumption.
2. Long supply chains involve multiple intermediaries, such as distributors, processors, wholesalers and retailers.
   1. Each extra stage adds energy use, emissions, packaging, refrigeration and cost.

Environmental Impacts of Long Supply Chains

1. Long supply chains raise total fuel use and CO₂ emissions, especially when refrigeration or air transport is needed.
2. Greater distance raises food miles, a measure of transport-related impact.
3. Longer chains widen social and economic distance, so less profit reaches farmers and consumers lose touch with where their food comes from.
4. Longer chains also raise the risk of food waste, as food can spoil during storage or transport.

Benefits and Trade-offs of Short Supply Chains

1. Shorter chains cut transport emissions, storage time and spoilage.
2. Farmers often earn more income through farmers' markets or direct sales.
3. Consumers gain fresher food and stronger community ties.
4. However, shorter chains can limit variety, seasonality and convenience compared with supermarkets.

Food Miles and the Cost of Year-Round Supply

1. Food miles measure the distance travelled from farm to consumer, often linked to transport GHG emissions.
2. Globalisation lets consumers buy foods grown thousands of kilometres away.

Year-Round Availability and Environmental Consequences

1. Year-round access usually relies on three energy-hungry methods.
   1. International imports from countries where the crop is in season.
   2. Controlled-environment agriculture such as heated greenhouses.