Peak water: what happens when the wells go dry?


Could the world be facing peak water? Or has it already peaked?


Peak oil has generated headlines in recent years, but the real threat to our future is peak water. There are substitutes for oil, but not for water. We can produce food without oil, but not without water.

We drink on average four litres of water per day, in one form or another, but the food we eat each day requires 2,000 litres of water to produce, or 500 times as much. Getting enough water to drink is relatively easy, but finding enough to produce the ever-growing quantities of grain the world consumes is another matter.

Grain consumed directly supplies nearly half of our calories. That consumed indirectly as meat, milk, and eggs supplies a large part of the remainder. Today roughly 40 per centof the world grain harvest comes from irrigated land. It thus comes as no surprise that irrigation expansion has played a central role in tripling the world grain harvest over the last six decades.

During the last half of the twentiethcentury, the world’sirrigated area expanded from close to 250 million acres (100 million hectares) in 1950 to roughly 700 millionin 2000. This near tripling of world irrigation within 50 years was historically unique. But since then the growth in irrigation has come to a near standstill, expanding only 10 per centbetween 2000 and 2010.

In looking at water and our future, we face many questions and few answers. Could the world be facingpeak water? Or has it already peaked?

Key points

  • Peak water poses a greater threat to our future than peak oil. We can produce food without oil but not without water.
  • Overpumping of aquifers has created water-based food bubbles, which will burst once aquifers are depleted. Among the countries currently overpumping their aquifers are the world’s three biggest grain producers- China, India and the United States- which together, produce half of the world’s grain.
  • As competition for water resources from urban and industrial sources increases, agriculture will become the residual claimant on water supplies. As countries approach or arrive at peak water, aquifer depletion and shrinking grain harvests could lead to peak grain.
  • Water, not land, has emerged as the principle constraint on the expansion of food supplies.


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