World population will reach an estimated nine billion by 2050. Given this factor and continued economic development in today's low-income countries, the total global demand for food will increase approximately threefold over the coming half-century. Meanwhile, against this background, newly-occurring global environmental changes such as climate change are anticipated to affect food production. Other incipient large-scale environmental changes likely to affect food production include stratospheric O3 depletion, the accelerating loss of biodiversity (with knock-on effects on crop and livestock pest species) and the perturbation of several of the great elemental cycles of N and S. The ways in which these various environmental influences affect the production of food (crops and livestock on land, and wild and cultivated fisheries) are complex and interactive. Uncertainties therefore persist about how global climate change is likely to affect world and regional food production. On balance, recent modelling-based estimates indicate that, in the medium to longer term, if not over the next several decades, climate change is likely to affect crop yields adversely, especially in food-insecure regions. The prospect of increased climatic variability further increases the risks to future food production. Given these possible though uncertain adverse impacts of climatic and other environmental changes on world food production, there is a need to apply the Precautionary Principle. There are finite, and increasingly evident, limits to agro-ecosystems and to wild fisheries. Our capacity to maintain food supplies for an increasingly large and increasingly expectant world population will depend on maximising the efficiency and sustainability of production methods, incorporating socially-beneficial genetic biotechnologies, and taking pre-emptive action to minimise detrimental ecologically-damaging global environmental changes.