Driving Forces

The most important driving force for future agricultural production is population growth. The current population of about 6 billion people will grow to more than 8 billion in 2030. The world's population is still growing at an impressive rate, but slower than before. This situation translates into an overall reduction of the growth rate of agricultural production, although in absolute terms a massive increase of production will still take place between now and 2030 to satisfy the growing demand. For example, Seckler et al. (1999) estimated that by 2025 cereal production will have to increase by 38% to meet world food demands. The World Water Vision, an outcome from the Second World Water Forum in The Hague in 2000, estimated a similar figure of 40% based on various projections and modelling exercises (Cosgrove and Rijsberman, 2000). Adopting UN mid-range population estimates of 8.9 billion people combined with the minimum caloric requirement of 2200 calories per day, means that a total of about 20 trillion consumable calories have to be produced. Current levels are about 14 trillion calories, which means an increase of 42%. However, given the range in population estimates as provided by the UN this figure can be between 14% and 71%.

The demand does not grow only because of an increasing number of people, but also because they eat more. When GDP per capita rises, the food preference of the people changes and the daily calorie intake per capita rises. Overall crop demand and production will therefore increase considerably more than the increase of the population. Increase in crop demand can be met in three different ways: expanding the land area, increasing the frequency with which it is cropped and boosting yields (Fischer et al., 2003). It has been suggested that ceilings may be approached in all three factors, but FAO's study, World Agriculture: Towards 2015/2030, does not support this view at the global level (FAO, 2002). About 80% of the projected growth in crop production in developing countries comes from yield increases (67%) and intensification of the cropping pattern (12%). The rest will come from extending cultivated land.

© CAB International 2004. Climate Change in Contrasting River Basins

RESULTS MODELS DRIVERS

Fig. 12.1. Overview of model and data components related to the IMPACT model.

The estimated contribution of yield increases and intensification of the cropping pattern is partly the result of the increasing share of irrigated agriculture in total crop production, since the yields of irrigated crops are generally higher and irrigated agriculture is generally more intensive than rain-fed agriculture.

This chapter deals with the results of a study that aimed at assessing global impacts on food demand and security under climate change and autonomous adaptation. The core of the study is an integrated modelling framework that allows assessment of food trade, food demand and food production, the latter coupled to a global water balance model. The results are compared with the effects at basin and field scale as discussed in Chapter 3.

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