Food security means that a population has a reliable supply of enough safe and nutritious food. Several biological factors can reduce it.
- A rising human population increases the demand for food, so production has to keep rising too.
- Increasing animal farming means more animals are reared, and meat and fish consumption is rising. Livestock are consumers, and energy is lost at each trophic level, so producing meat needs far more land than growing crops for people to eat. Overfishing also reduces fish stocks.
- New pests and pathogens spread through trade and travel and as the climate changes. A new fungus or insect can kill or damage crops and livestock, so the yield falls.
- Environmental change caused by human activity, such as climate change, can bring drought and flooding, and soil damage. These cut the yield of crops.
- Sustainability issues include using land for biofuel crops instead of food, and the high cost of agricultural inputs such as fertiliser, pesticides and animal feed, which poorer farmers may not be able to afford.