Main question

It is estimated that about 800 million people in the developing world do not have enough to eat. More than half of these undernourished people (61 percent) are found in Asia, while sub-Saharan Africa accounts for almost a quarter (24 percent). In terms of the percentage of undernourished people of the total population, the highest incidence is found in sub-Saharan Africa, where it is estimated that one-third of the population were undernourished.

Figure 1. Percent of water consumption from total water resources by natural-economic regions of the world in 2000. (Source: Shiklomanov, 2003)

An enormous amount of water is required to produce food, where often is forgotten that non-irrigated crops consume also water that cannot be used for other purposes. According to the latest estimates about 10% of all crops are irrigated while at the same time 43% of the global grain production originates from irrigated lands. Moreover from all water diverted 62% is used for irrigation and 21% and 17% for domestic use and industry, respectively.

The main question is whether climate change will influence food production and if so, what can be done to minimize the adverse impact.

Figure 2. Global trends in food production over the last 40 years expressed as food production per capita. Depicted figure is indexed with the year 1961 set as 100.

Result and conclusions

The International Institute for Applied Systems Analysis presented a study based on their GAEZ approach (Global Agro-Ecological Zonering), which indicates that the impacts of climate change on crop production are geographically unevenly distributed. Developed countries experience an increase in production. In contrast, developing regions suffer a loss in cereal production in all estimates. Within the group of developed countries, gains of 3-10% in cereal production occur for North America, and similar for the Former Soviet Union. Western Europe suffers losses in most projections of up to 6%.

In contrast to these figures, results presented by the International Food Policy Research Institute show that the increase in irrigation water use will be only 4%, mainly as a result of water shortages. According to their business as usual scenario farmers will produce 10% less cereals leading to sharply increased food prices.

In addition to these theoretical approaches, experimental data were collected to assess the impact of CO2 enriched air on crop growth. A vast amount of experiments have been carried out over the last decades, where the impact of increased CO2 levels on crop growth has been quantified. The Center for the Study of Carbon Dioxide and Global Change in Tempe, Arizona, has collected and combined results from these kinds of experiments. For example for rice it is expected that average biomass increases are 31% for increases in CO2 air concentrations of 300ppm, but variation is substantial. According to the Intergovernmental Panel on Climate Change (IPCC) agriculture accounts for about one-fifth of the projected anthropogenic greenhouse effect, producing about 50 and 70%, respectively, of overall anthropogenic CH4 and N2O emissions and approximately 5% of anthropogenic emissions of CO2.

A major obstacle for farmers to overcome the impact of climate change is the expected increase in successive years of overly dry and/or wet spells. A poor farmer might overcome a one-year drought followed by a normal year, but a period of two or more consecutive years of drought, even followed by a longer period of normal years, will be catastrophic to this farmer.

Figure 3. An increase in consecutive years of extremes is expected.

There exists little information on the conditions under which adaptation measures are likely to be adopted. The limited research to date indicates that producers rarely respond to climate change alone, and that adaptation to climate change risks would be undertaken as part of ongoing production and risk management decision making.

Please feel free to contact the Project Leader of this project for more information.