But few mention the declining supply of water that is needed to grow irrigated and rain-fed crops.
An often-mooted solution to the food crisis is to breed plants that produce the ultimate high-yielding, low water-consuming crops. While this is important, it will fail unless we also pay attention to where the water for all our food, fibre and energy crops is going to come from.
Essentially, every calorie of food requires a litre of water to produce it. So those of us on Western diets use about 2,500-3,000 litres per day. The expected addition of a further 2.5 billion people to the world by 2030 will mean that we have to find over 2,000 more cubic kilometres of fresh water per year to feed them. This is not any easy task, given that current water usage for food production is 7,500 cubic kilometres per year and supplies are already scarce.
Facing severe water scarcity
A few years ago, my organisation, the International Water Management Institute (IWMI), demonstrated that many countries are facing severe water scarcity, either because insufficient fresh water is available or because they lack investment in water infrastructure, such as dams and reservoirs. What makes matters worse is that this scarcity predominantly affects developing countries where the majority of the world's 840 million under-nourished people live.
Serious and extremely worrying evidence indicates that water supplies are steadily being used up. And the causes of water scarcity are much the same as those of the food crisis: demand exceeds a finite supply.
The world's population is projected to grow from 6 billion to 8.5 billion by 2030 and unless we change the way we use water and increase water productivity — ie. produce more 'crop per drop' — we will not be able to feed them. That is the conclusion of the IWMI's recent Comprehensive Assessment of Water Management in Agriculture and its book, Water for Food, Water for Life, which drew on the work of 700 scientists.
Compared with the long-term threat of climate change, this problem is coming fast upon us. The latest estimates indicate that in 25 years' time we will not have enough water to feed ourselves and the current food shortage could become a perpetual food crisis. Yet, although the effects of water scarcity will be profound, very little is being done about it in most countries. Indeed, just as in other areas of agricultural research and development, investment in providing and managing water resources has declined steadily since the Green Revolution. This must now change.
Since the UN Millennium Goals were formulated in 2000, much of the water agenda has focused on providing drinking water and sanitation. This water comes from the same sources as agricultural water. As we urbanise and improve living standards, there will be increasing competition for drinking-quality water, putting agriculture under further pressure. While improving drinking water and sanitation is vital for raising health and living standards, we cannot afford to neglect provision and improved productivity of water for agriculture.
There are potential solutions. Better water storage has to be considered. Ethiopia, which is typical of many sub-Saharan African countries, has a water-storage capacity of 38 cubic metres per person. By comparison, Australia has almost 5,000 cubic metres per person, yet, in the face of current climate change, even that may be inadequate. We will certainly need to build new large- and medium-sized dams to deal with the critical lack of storage in Africa.
Other simpler actions are also part of the solution. These include constructing small reservoirs and using groundwater systems sustainably, including artificial groundwater recharge and rainwater harvesting for smallholder vegetable gardens.
Improved year-round access to water will help farmers maintain their own food security using simple supplementary irrigation techniques. Redesigning both the physical and institutional arrangements for some large, and often dysfunctional, irrigation schemes will bring productivity increases. Safe, risk-free re-use of wastewater from growing cities will also be needed. Of course, drought-tolerant crops and the infrastructure to get fresh food to markets must be developed in parallel.
I and my water science colleagues are raising a warning flag. Significant investment in both R&D and water infrastructure development are needed if dire consequences are to be avoided.
by Colin Chartres