Food choices and diets
Big idea: What we eat has huge environmental implications. Food miles, trophic efficiency, and the type of food all affect the ecological footprint of our diet.
Factors affecting food choices
- Climate — determines what can be grown locally
- Water availability — limits irrigation-dependent crops
- Cultural and religious factors — dietary restrictions, traditions
- Economic development — wealth allows more choice, more meat
- Technology — refrigeration, transport extend options
- Environmental value systems — beliefs about sustainability, animal welfare
Trophic efficiency and diet
Only ~10% of energy transfers between trophic levels. This means:
Plant-based diet
- Eating at trophic level 1 (producers)
- More energy-efficient
- Less land, water, emissions per calorie
- Lower ecological footprint
Meat-based diet
- Eating at trophic level 2+ (consumers)
- ~90% energy lost at each transfer
- More land, water, emissions per calorie
- Higher ecological footprint
Producing 1 kg of beef requires ~15,000 litres of water and ~7 kg of grain. The same land could produce much more plant protein directly!
Food miles
Food miles contribute to carbon emissions, but the full picture is more complex — local food is not always lower-impact if production is inefficient.
PAST PAPER PATTERN: "Explain why diets differ between regions." Link to: climate suitability, water availability, cultural/religious factors, economic development, technology, EVS. Give specific examples!