AS IT SCOURS the universe for signs of extraterrestrial life, nasa has a motto-cum-mission-statement: "Follow the water". About 70% of the human body is made up of water, it says, and 70% of Earth's surface is covered in the stuff. "Water creates an environment that sustains and nurtures plants, animals and humans, making Earth a perfect match for life in general." If water is a proxy for life itself, it is perhaps not surprising that worries about the health and availability of supplies here on Earth can take on apocalyptic overtones. A scorching, arid future marked by a fierce, bloody struggle for a few drops of water is a standard theme of dystopian fiction and film-making. This report will examine how close such nightmares are to reality. It will look at the state of the world's freshwater and at the increasing demands on it, and consider the ways they can be met. The first thing to recognise is that the 70% figure is largely irrelevant to the debate. The sea it represents is salty, accounting for 97.5% of all the water on Earth. A further 1.75% is frozen, at the poles, in glaciers or in permafrost. So the world has to rely on just 0.75% of the planet's available water, almost all of which is subterranean groundwater, though it is from the 0.3% on the surface that it draws 59% of its needs (see chart on next page). This report will argue that misuse of water may indeed lead to a series of catastrophes. But the means to dodge them are already known, and new technologies are constantly evolving to help.
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