Wired Science

Too Many People, Not Enough Water

Water shortages are a looming potential crisis in the American Southwest (See Peak Water for that story). But they're already a dangerous reality in many other parts of the world where populations are growing and freshwater supplies are shrinking.

Nearly one-third of the world's inhabitants don't have reliable access to clean water, according to the International Water Management Institute; supplies are either unsafe,  unaffordable or just not there. Some 3 million people - most of them children - die every year from diseases spread by contaminated water.

Without drastic changes, the picture will only get uglier. By 2025, 1.8 billion people will live in countries with "absolute water scarcity," according to a report released this year by the United Nations Environment Program.

"We've created a crisis that's the equivalent on the ground of greenhouse gas emissions in the air," says Maude Barlow, author of the just-released book, "Blue Covenant: The Global Water Crisis and the Coming Battle for the Right to Water".

In fast-growing China's densely-populated north, home to about 500 million people, the underground aquifers that supply most the region's water are rapidly becoming tapped out. The water table beneath Beijing has dropped by nearly 200 feet in the last two decades. India is in similarly dire straits. The giant country has 20 percent of the earth's population, but only four per cent of its water.  Water tables are dropping fast in some of India's main agricultural areas, and in those of nearby Iran and Pakistan. The mighty Indus and Ganges rivers are tapped so heavily that, except in rare wet years, they no longer reach the sea. The same is true of Egypt's Nile and China's Yellow River.

As water supplies decrease, competition to control them is intensifying. Several major rivers are shared uneasily by countries with a history of hostilities: the Tigris-Euphrates (Turkey, Syria and Iraq), the Nile (Egypt, Ethiopia and Sudan), the Ganges (India and Bangladesh), the Mekong (Cambodia, Laos, Thailand and Vietnam) and the Jordan (Syria, Israel and Jordan). Rival nations have come to blows many times in the last 50 years to protect their water supplies - from Israel and Syria swapping artillery shells over control of the Jordan River to armed skirmishes between Ecuador and Peru over access to the Cenepa River.

But countries, at least, have international institutions in which to address competing claims. "We're much more likely to see violence over water at the sub-national level," says Peter Gleick, head of the Pacific Institute, a California-based water policy think tank. Battles have broken out in recent years between armed groups of farmers in China, India, Afghanistan, Somalia and elsewhere over access to rivers and wells. In Sudan's Darfur region, water shortages have rendered much farm land useless, exacerbating conflict between tribal groups over what remains. 

Population growth is the prime culprit behind the growing water shortages. Since 1950, the number of people on the planet has mushroomed from 2.5 billion to 6 billion. All those mouths need food - and generating all that food requires enormous quantities of water. Seventy per cent of all the water humans use goes to support agriculture.

That heavy use, in turn, is dictated in large part by what people eat. The world's most popular grain is rice - an irrigation-intensive crop that is often grown with extraordinary inefficiency. Rice farmers in India typically get less than half the yield per acre that their counterparts in China do - and they use 10 times more water than necessary to get it. Economic development in some ways makes matters worse. As people's living standards rise, they tend to eat more meat. But it takes tremendous quantities of water to raise animals for food. Growing a ton of grain requires 1,000 tons of water; a ton of beef takes 15,000. Around 1,300 gallons of water are used to generate a single hamburger.

Climate change also seems to be exacerbating matters. Reduced rainfall and massive droughts in Africa's Sahel region since the 1970s are widely attributed to changes caused by a warming of the ocean's surface. Many scientists also believe rising temperatures are part of the reason for the decline of the Sierra Nevada snowpack, source of much of the Colorado River water that feeds America's Southwest. Similarly, a recent United Nations report warns that melting Himalayan glaciers may mean less water in the future for India, Nepal, Pakistan and China.

Nonetheless, many hydrologists believe there is still plenty of water for everyone. The issue, they argue, is less one of supply than distribution. After all, unlike oil, water doesn't disappear after it's been used. After being poured in a glass or on a field, water eventually winds up in the ground or the ocean where it will evaporate, join a cloud and return to Earth again somewhere else. The problem is where that "somewhere else" tends to be. There's no shortage of rainfall in places like Canada; but many of the fastest-growing cities - in the United States and elsewhere - are in arid areas. 

Still, there are plenty of ways most parts of the world could be making better use of whatever aquatic resources they have. More efficient farming techniques - better irrigation systems, better chosen and perhaps genetically engineered crops - could make a major difference. Simply cutting avoidable losses would help; some cities lose as much as half their water through leaky pipes. Huge amounts of wastewater  could also be recycled, or treated and reused. (Technology can sometimes provide an unexpected boost: satellite images recently led to the discovery of what may be a vast, untapped aquifer under Darfur.)

All of these measures, though, take money - and political will. "If we act smarter, with more commitment and more aggressively, we can seriously reduce the threat of water-borne diseases and scarcity," says Gleick. "I just don't know that we will."