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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.
More specific causes of uncertainty in predicting future
trends are:
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.
Availability of freshwater
(linked with climate
change and with technology).
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).
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.
Uncertainties in future scenarios