The Environmental Food Crisis

Uncertainties in future scenarios

Human behaviour: Food preferences, ability to adapt to changing conditions for food supply, com- mitment to more equitable distribution of resourc- es or increased tendency to defend local resource base. (Economic factors as major proximate driv- er of food production decisions: supply/demand curves, input costs, extent of exposure to interna- tional markets, government policy as expressed in subsidies, tariffs, etc).

As defined by the FAO, food security exists when all peo- ple, at all times, have physical and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life. Future food security depends on developments in both supply and demand, but projections for these vari- ables are cursed with uncertainty. On the demand side, population and economic growth are particularly sub- ject to a high degree of uncertainty. Key uncertainties for future supply have to go with agricultural productivity and energy markets. In addition, developments are con- tingent on new policies being put in place. Climate change: While mean temperature changes are quite well modelled, rainfall changes and extreme weather events are much less so, particularly at small- er scales, neither are extreme weather conditions pre- dictable today. Energy supply: If peak oil supply is reached within the period under consideration, this will have major conse- quences for the economics of virtually all aspects of food production as well as on likely demands for biofuels. Technological advances in food production , such as by the use of genetically modified crops may also influence yield projections. More specific causes of uncertainty in predicting future trends are:

Impacts of pests and diseases (including alien in- vasive species) on food supply.

Actual versus predicted population growth.

Major disease outbreaks in humans.

Other catastrophic events (war, major earthquakes, volcanic events, etc).

The future impact of some of these is so unpredictable that it is difficult to see how they can realistically be incorporated into any quantitative models, other than through including some essentially arbitrary tolerance limits in calculating necessary food supplies. Overall, no fully integrated model currently exists that assesses agriculture in a holistic way. Current models and scenarios focus on one or very few of these areas, e.g., land use change (IMAGE model), global climate models (e.g., UK Met office model), or are add-ons to these models (e.g., GLOBIO biodiversity model) with feedbacks and interconnections not fully integrated.

Availability of freshwater (linked with climate change and with technology).

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