David Molden, BBC Green Room 10 Feb 09
Rising populations and growing demand is making the world a thirsty planet, says David Molden. In this week's Green Room, he says the solution lies in people reducing the size of their "water footprints".
Today, one-third of the world's population has to contend with water scarcity, and there are ominous signs that this proportion could quickly increase.
Up to twice as much water will be required to provide enough food to eliminate hunger and feed the additional 2.5 billion people that will soon join our ranks.
The demands will be particularly overwhelming as a wealthier, urbanised population demands a richer diet of more meat, fish, and milk.
The water required for a meat-eating diet is twice as much needed for a 2,000-litre-a-day vegetarian diet.
Cities and industries will also demand more water. Ironically, even new endeavours pursued in the cause of environmental preservation, such as producing biofuels, will place even more pressure on dwindling water supplies.
Clearly, we are heading toward a tipping point that could soon bring us to a day of reckoning when we will have literally made one too many trips to the planetary well.
Given the current rate of development, we will not be able to provide water for producers to grow enough food and sustain a healthy environment.
The only solution is to learn how to live with less water by making much better use of what we have.
Better water management is good for farmers, good for the environment and good for all of us. We already know many of the ingredients to make this happen; the big question is why isn't it happening?
Trickle effect
The good news is that it does happen.
People are reaching for tools - new and old - to produce more food with less water.
They are adopting more precise irrigation practices, such as drip and sprinkle irrigation.
For example, many farmers in Nepal and India now regularly use low-cost drip irrigation to grow vegetables.
In sub-Saharan Africa, just a little water - combined with improved crop varieties, fertiliser and soil management - can go a long way.
Farmers can double the yield per hectare they currently harvest, and double the amount of food produced per unit of water.
Over the last two decades in Asia, sales of pumps that allow farmers to more reliably and precisely apply water to their crops, have skyrocketed.
Rice farmers in the region are now also saving water by a practice known as "wet and dry" irrigation, rather than following the traditional practice of keeping rice fields constantly flooded.
Also, many farming communities are getting organised into associations for more effective irrigation management.
But the bad news is that change isn't happening fast enough.
For example, there are still far too many ill-maintained and poorly operated irrigation systems across Asia that use two times more water than is really needed.
In sub-Saharan Africa, the problem is not water being wasted, but the simple yet devastating issue of access.
Despite water being available in nature, many farmers routinely lack enough water to produce food to feed their families.
'Water miles'
Why is it that some areas use water so carelessly?
One problem lies with public policies that fail to connect the interests of different user groups.
For example, farmers may see little self-interest in being more conservative with water if the benefits flow to cities and not to them.
Although, broadly speaking, water is a precious commodity, for many users its costs are negligible, so there is no incentive to conserve.
Many countries do not invest enough in water to enable poor rural communities to grow more food.
In the US and Australia, annual per capita water storage is more than 4,000 cubic metres. Yet in much of sub-Saharan Africa it is less than 100 cubic metres; poor countries simply cannot afford investments in large hydraulic infrastructure.
Nonetheless, the International Water Management Institute (IWMI) and other research organisations have identified new and more affordable opportunities for low-cost water investment.
For example, resource-poor farmers can afford low-cost drip irrigation kits, whereas conventional irrigation, which costs more than $4,000 per hectare, is well beyond their means.
Unfortunately, while we think we know the answers, reality is more complex.
We have dramatically altered natural water systems in the quest for more water control.
Unwittingly, we have created salinity problems, dried up rivers and have caused groundwater tables to decline.
Institutions that govern water have not adapted to address these issues. Added to this is the fact that we don't fully understand what new water problems will result from climate change.
While we desperately need to know more about water resources, basic data and knowledge are hard to get because of a lack of investment.
The industrialised world is quick to point its finger at agricultural producers, blaming them for water woes, but it is our food habits that drive the problem.
When 50% of food is wasted after it leaves farmers' fields, it leads to an equivalent water waste of 50% because wasted food is also wasted water.
Action is urgently required on several fronts: we must continue to encourage the many local actions that are having a positive impact now; we must establish policies that create incentives for farming communities to invest in better water management; and we must invest in the infrastructure and the knowledge systems needed to manage complex water systems for the benefit of all.
Each of us can make a difference if we first consider the water implications of our lifestyles and the "water footprint" we are leaving behind.
Dr David Molden is deputy director of research for the International Water Management Institute (IWMI)
The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website
