Agriculture will remain the dominant user of water at the global level. In many countries, in particular those situated in the arid and semi-arid regions of the world, this dependency can be expected to intensify. Water appropriation by agriculture experienced strong growth with the Green Revolution. The contribution of irrigated agriculture to food production is substantial but the rate of growth will be lower than in the past. Both irrigated and non-irrigated agriculture still have scope for increasing productivity, including water productivity. Arguably, the expansion of irrigated agriculture protected people on the nutritional fringe from premature death, and preserved tracts of land under forest and wetlands from encroachment by hard-pressed farmers. However, pressures to encroach on such lands persist.
Within the current demographic context, the global food security is slowly improving and towards 2050, the increased world population could enjoy access to food for all. The fact that close to 800 million people are at present ravaged by chronic undernourishment in developing countries is not due to a lack of capacity of the world to produce the required food, but to global and national social, economic and political contexts that permit, and sometimes cause, unacceptable levels of poverty to perpetuate. Malnutrition is being alleviated, albeit slowly, and as the share of food slips lower in household budgets, the prospects for agriculture to internalize its costs may improve. Water still has a large unmet potential to help alleviate poverty and undernourishment. In taking this direction, agricultural-water management will continue to require better integration with rural household water uses, and to make more positive contributions in environmental management. Food for all could be achieved much earlier than present projections indicate, provided that the necessary policies are backed with the necessary resources. The economic, social and environmental cost of continued food insecurity for hundreds of millions of people is high.
Agriculture can use water more efficiently than present practices indicate. Technology for efficient transport of water from the site of abstraction to the field, and for delivering it to the crop plants with a minimum of losses, is available and is being progressively applied where water is scarce. Irrigation-water-use efficiency increases when the right policy and market incentives are in place. As competition for limited water resources and pressure to internalize environmental impacts intensify in a number of countries, agriculture and, in particular, irrigation comes under growing pressure to review and adapt its policies and institutions, including the water rights and allocation system. Under such circumstances as in the Near East/North Africa region, current water efficiency is relatively high and projected to further increase. Data show an aggregate low-water-use efficiency in the water-rich Latin America region, and it is not seen as increasing significantly in the future because no other large-scale users compete with agriculture; locally, however, wherever water is scarce, high efficiency is also obtained in that region. Agriculture can also increase the use of recycled water and of water stemming from non-conventional sources.