Colin Chartres, BBC Green Room 20 Aug 08;
Limited availability of fresh water is often overlooked as a cause of food scarcity and environmental decline, according to Colin Chartres. Governments should be ramping up efforts to make sure we have enough to grow crops as well as enough to drink, he argues.
This year, the world and, in particular, developing countries and the poor have been hit by both food and energy crises.
As a consequence, prices for many staple foods have risen by up to 100%.
When we examine the causes of the food crisis, there are many contributing factors: a growing population, changes in trade patterns, urbanisation, dietary habits, biofuel production, climate change and regional droughts.
Thus, we have a classic increase in prices as a result of high demand and low supply. However, few commentators specifically mention the declining availability of water that is needed to grow irrigated and rain-fed crops.
According to some, the often mooted solution to the food crisis lies in plant breeding that produces the ultimate high yielding, low water-consuming crops.
While this solution is important, it will fail unless attention is paid to where the water for all the food, fibre and energy crops is going to come from.
Thirsty world
The causes of water scarcity are essentially identical to those of the food crisis.
There are serious and extremely worrying factors that indicate water supplies are close to exhaustion in some countries.
Population growth over the next four decades will see the number of people in the world increase from 6.5 billion up to 9.0 billion.
Essentially, every calorie of food requires a litre of water to produce it.
So on average, we require between 2,000 and 3,000 litres of water per person to sustain our daily food requirements.
We will have 2.5 billion extra mouths to feed by 2050, so finding the extra water each year will not be an easy task, given that it is more than double what is currently used in irrigation.
We also have to bear in mind that the availability of new fertile land in humid areas for rain-fed farming is extremely limited.
Recent studies, as part of the Comprehensive Assessment of Water Management in Agriculture, have indicated that we will not be able to produce all the food, feed and fibre required in 2050 unless we improve the way we manage water.
Invest and survive
A few years ago, the International Water Management Institute (IWMI) demonstrated that many countries are facing severe water scarcity, either as a result of a lack of available freshwater, or as a consequence of a lack of investment in 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 undernourished people live.
However, there are potential solutions. These include more water storage, improved management of irrigation systems and increasing water productivity in irrigated and rain-fed farming systems.
All of these will require investment in knowledge, infrastructure and human capacity.
Better water storage has to be considered. Ethiopia, which is typical of many sub-Saharan African countries, has a storage capacity of 38 cubic metres per person.
In contrast, Australia has almost 5,000 cubic metres per person, an amount that in the face of current climate change impacts may be inadequate.
Whilst there will be a need for new large and medium-sized dams to deal with this critical lack of storage in Africa, other simpler solutions will also be part of the equation.
These include the construction of small reservoirs, sustainable use of groundwater systems 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.
The redesign of both the physical and institutional arrangements of some large and often dysfunctional irrigation schemes will also bring the required productivity increases.
Safe, risk-free re-use of wastewater from growing cities will also be needed.
Of course, these actions need to be paralleled by development of drought-tolerant crops, and the provision of infrastructure and facilities to get fresh food to markets.
Resource competition
Since the formulation of the UN Millennium Development Goals (MDGs), much of the water agenda has been focused around the provision of drinking water and sanitation.
This puts demand on the same resources as agricultural water; and as we urbanise and improve living standards, increasing competition for drinking water from domestic and other urban users will put agriculture under further pressure.
While improving drinking water and sanitation is vital with respect to health and living standards, we cannot afford to neglect the provision and improved productivity of water for agriculture.
Current estimates indicate that we will not have enough water to feed ourselves in 40 years time, by when the current food crisis may turn into a perpetual crisis.
Just as in other areas of agricultural research and development, investment in the provision and better management of water resources has declined steadily since the Green Revolution.
My water science colleagues and I are raising a warning flag that significant investment in both research and development and water infrastructure development is needed if dire consequences are to be avoided.
Dr Colin Chartres is director-general of the Sri Lanka-based International Water Management Institute (IWMI), a not-for-profit research organisation focusing on the sustainable management of water resources for food, livelihoods and the environment
To read the summary of "Water for Food, Water for Life", visit http://www.iwmi.cgiar.org/Assessment
The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website
