Mean value climate change

The IMPACT-WATER model simulated the time period 1996-2025 with climate change acting as shock to the climate. We are reporting the results from 2000 onward to allow for model adjustments to the 'mathematical shock'. The model is driven not only by climate, but also by socio-economic change and the associated technological changes. As seen in Fig. 12.3, the prices of wheat decline from 2000 to 2025 as the economic impacts of yield increase are felt by the system. Note, however, that the climate change scenarios preserve this trend, but impact the level of final prices. This same phenomenon is illustrated in Fig. 12.4, showing an increase in global food demand mainly as the result of increased population and lower prices. Climate change again impacts the rate and level of this increased demand.

To present as much information as possible from the analysis, the impact of climate change on food price, demand and production will be presented as changes in the average of the variable over the period 2001-2025. Please note that what is being presented is the relative change from the base, not climate change condition. So while demand is presented as decreasing, that is only in respect to the base; in fact it has been increasing in an absolute sense even under climate change.

A series of graphs present the results for three main crops: wheat, rice and maize. Figure 12.5 shows that for all climate change scenarios and all three crops, total production goes down. Examining the above figures shows that rain-fed production of all crops decreases significantly due to decreases in effective precipitation. Irrigated production decreases more for wheat and rice, but increases for maize. The decrease in global production results in an increase in world market prices. Rice shows a price increase over 100% and wheat almost 100%, while maize experiences a less than 50% increase. These price changes correlate directly to the production changes (Fig. 12.6).

Fig. 12.3. World market prices for wheat.

2010 2015

Year

2.4. World food demand for wheat.

Base: 1961-1990 CC scenarios 900,0001--y ,---_--=-17

n (M600,000 S 500,000 -m— 400,000 -Lg Dl 300,000 -H

Rice Wheat Maize

Fig. 12.5. World total (irrigated and rain-fed) production of rice, wheat and maize.

Base: 1961-1990

400,000

350,000

Rice Wheat Maize

Fig. 12.6. World irrigated production of rice, wheat and maize.

Base: 1961-1990

CC scenarios

Fig. 12.6. World irrigated production of rice, wheat and maize.

CC scenarios

Fig. 12.7. Average effect of ENSO years on global food demand for major crops.
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