Food security means that everyone in a population has enough safe, nutritious food at all times. Several biological factors put food security under pressure.
The human population is increasing, so more food is needed every year. In wealthier populations, diets are changing and people eat more meat. Raising animals for meat uses much more land, water and crop food than growing plants for people to eat directly, so this raises the demand on farmland.
New pests and new pathogens can spread to crops and livestock and destroy large amounts of food. Environmental change, such as drought, floods or higher temperatures, can reduce yields. Farming also has to be sustainable, which means it must not use up resources or damage ecosystems, so that food can still be produced in the future. Finally, the cost of agricultural inputs such as fertiliser, pesticide and fuel can rise, which makes food more expensive to produce.