Water covers about two-thirds of the Earth’s surface, but precious little can be used by human beings. Only 2.5 percent — a veritable drop — of the world’s water is not salty, and two-thirds of that is frozen in the ice caps and glaciers. Of the remaining third, 20 percent is located in remote places, and much of the rest is delivered via floods and monsoons, which means it is often unusable or wasted. Do the math and the results are grim: We can use less than 0.08 percent of the water on the planet.

At the same time, the demand for water is expanding explosively. Water use is expected to increase 40 percent over the next two decades. About 3 billion people will face water shortages by then. There are several reasons for the surge. Populations are rising, but more important is the rising level of affluence worldwide. As people acquire more wealth, their environmental footprint grows larger. Quite simply, the modern lifestyle demands more inputs and puts a greater strain on natural resources. While world population tripled in the last century, water use increased six times.

The main culprit is agriculture. Seventy percent of the water that is used today is used for agriculture. Moreover, changing tastes — and the modern agricultural techniques required to feed them — use more water. Another important contributor is pollution. Development not only increases demand for water but also renders unusable other supplies. Waste, the byproduct of modern industry, diminishes the amount of water available for more basic needs.

As a result, the World Water Council estimates that the gap between the amount of water needed to feed the world and the amount that will be available worldwide will be about 17 percent. According to the United Nations Environment Program, water shortages and global warming are the greatest environmental challenges of this millennium.

A shortfall could have disastrous consequences. Water shortages already have deadly effects. Twenty percent of the world’s population has no access to safe drinking water, and 50 percent have poor sanitation. Nearly half a million infants die annually as a result.

Shortages will be felt in different ways. Severe shortages could trigger population movements as desperate populations move to less arid regions. Just as alarming is the prospect of international conflicts as governments try to claim scarce resources. A key concern in Israel has been the water rights that accrue to the possessor of the Golan Heights. Several nations in Southeast Asia worry about water flow in the Mekong River; China’s development is diverting an increasing amount of water and posing serious challenges to downstream consumers. In Central Asia, water shortages are second only to extremist groups as a cause of tension among nations. Uzbekistan is reported to have carried out military exercises that practice seizing neighboring water reservoirs. These tensions are found elsewhere around the globe.

Technology offers a partial solution. Large-scale desalination could help ease shortages, but it would create large quantities of brine that would have to be disposed of. Moreover, it is likely to be expensive, which would mean that it would do little to help the poor who need water the most — and can afford it least.

Many experts believe that better management of water resources is the solution to future problems. Cutting pollution would be one immediate boon. In agriculture, outdated irrigation systems result in the loss of as much as 50 percent of the water used for crops. The acknowledgment that water is a public good — a shared resource — would go a long way toward minimizing cross-border frictions created by water scarcity.

Unfortunately, better water management requires political will. Publics, and especially those in the developed world, have to become aware of their profligate ways. Governments must adopt policies that encourage more efficiency; if that is difficult in the developed world, it is even more difficult in developing nations that have less to spend on more efficient technologies and more stringent use policies. Clearly, technological cooperation and the sharing of expertise and knowledge will be critical to future progress.

There have been some promising signs. Ten Asia-Pacific nations recently signed a joint statement calling for ways to halt the waste of water. The statement will be presented at the World Summit for Sustainable Development in Johannesburg, South Africa, in August, and at the Third World Water Forum which will be held in Kyoto next March. The record of such conferences, however, offers little grounds for hope of a sustainable solution.

In a time of both misinformation and too much information, quality journalism is more crucial than ever.
By subscribing, you can help us get the story right.