A Thirsty World

The U.S. intelligence community believes that by 2015 nearly half of the world’s population—more than 3 billion people—will be living in countries that lack sufficient water. They estimate that even more genetically modified crops or projects to desalt seawater will not substantially help. The population is not only growing but using more water, even though the world’s total supply remains the same. This scarcity could put a major brake on the world’s development this century. If states substantially invest in water-related infrastructure and management policies, we can expect the projections presented below.

Yet despite these efforts, many countries will still face “physical water scarcity in 2025:” their water needs will outstrip supplies no matter what measures are taken. Others will be faced with “economic water scarcity:” they will lack the financial and institutional capacity required to increase their water supplies by 25 percent. Since 1900, world population has doubled yet the amount of fresh water used has increased more than six-fold. Agriculture is by far the largest consumer of water, mostly because of the spread of irrigation. Two-thirds of all the water consumed in the world goes to farming, a share expected to shrink only slightly by 2025. More efficient irrigation techniques are clearly the first and crucial step to reducing water use. Today, there is about 6,800 m3 of water available per person on a yearly basis.

If current trends continue, only 4,800 m3 will be available in 2025. This is an optimistic calculation because it is based upon estimates of all the water flowing in rivers after evaporation and infiltration into the ground. It does not take into account the minimum required to maintain river ecosystems, for example. Nor does it reflect the difficulty in accessing all of this water or its extremely unequal distribution. When per capita water supply is less than 1,700 m3 per year, an area suffers from “water stress” and is subject to frequent water shortages. In many of these areas today, water supply is actually less than 1,000 m3 per capita which causes serious problems for food production and economic development. Today, 2.3 billion people live in water-stressed areas. If current trends continue, water stress will affect 3.5 billion—or 48 percent of the world’s projected population—in 2025.