A Floating Planet

The failure to provide drinking water and adequate sanitation services to all people is perhaps the greatest development failure of the 20th century.

The presence of water

Of all the water on earth, 97.5 per cent is too salty to drink. Two-thirds of the remaining 2.5 per cent is locked in the ice caps at the poles or in snow, though these areas are shrinking with the impact of global warming. There is water in the air – water vapour and then rain – and there is water held inside plants and other living beings, like ourselves. That leaves 16 million cubic kilometres, much of which is trapped in sedimentary rock too far underground to access. A further 90,000 cubic kilometres is in rivers and lakes. 500,000 cubic kilometres per year evaporate from the sea and from living plants, though about 60 per cent of that is returned in the form of snow or rain. The water held underground in aquifers, groundwater, has taken millions of years to accumulate. So the main source of fresh water, other than aquifers, is 'run-off, the water that seeps through the soil into rivers and lakes from their banks. This represents something like 34,000 cubic kilometres, which is about twice what is currently used. Rainfall amounts to some 110,000 cubic kilometres of which half is trapped by vegetation and around 30 per cent falls into rivers and lakes. The problem is that the gross figures for rainfall and river flows do not show how unevenly distributed that rainfall is, nor the differing rates at which aquifers, lakes and rivers assimilate the run-off. The flow from river bank into rivers is visibly rapid, though the speed of flow will be affected by the condition of the river banks, the amount of vegetation and the number of trees. The recharging of water into the shallower aquifers through the soil takes longer, and is not to be hurried, but penetration into the deeper water basins can take centuries, or never happen at all. Fred Pearce estimates that some 14,000 cubic kilometres are really accessible. Rivers, after all, flow through networks which when seen from the air resemble the jumble of veins in our hand; they are systems rather than single courses flowing neatly down a predetermined route. Indeed if the meandering of a river is disturbed, or the course of the river is straightened, and shortened, swamps will be drained and the run off will rush to the sea more quickly instead of penetrating the soil. In some seasons of the year their flow turns to flood, expanding across flood plains; at others it dries up. Rivers are by definition anarchic, and a great deal of human effort and resourcefulness over time has gone into attempting to control or direct their flow to guarantee stable supplies of water, especially for irrigation. One result has been the proliferation of dams across the world, built in the optimistic expectation that they would guarantee water supply and energy provision for generations; their unforeseen consequences are now emerging in the form of huge displaced populations, the accumulation of silt which would previously have flowed with the river and dispersed on deltas and flood plains, and which reduces the amount of water in reservoirs, the spread of poisonous algae as a result of inadequate oxygenation of the water, and the stagnant water and rotting materials expelling methane gas into the air from the surface of the reservoirs, among others. In the USA these monuments are now being rapidly dismantled; elsewhere, and particularly in China, they continue to be built on an increasingly massive scale, with accelerating negative consequences.

And the problem is even more complex than that. Humanity has controlled and contained rivers – it has also polluted them. The refusal of rivers to acknowledge national frontiers has produced other kinds of conflict, to which we shall return. The rain, while replenishing the planet's resources, falls unevenly – flooding here, while leaving deserts there. And the supply of water from rivers, even after the construction of dams, has proved inadequate for the needs of industry, agriculture and people, so attention has turned to the giant aquifers beneath the ground. The current statistics for the depletion of aquifers are truly alarming, especially in the knowledge that the deeper water basins are pretty much inaccessible.

It is easy to be blinded, or depressed, or confused (or all three) by statistics, especially with these astronomical numbers. What we need to know is how much water is available to us, where that water is, how it is currently used, and how we can use it differently. It is more than an issue of conservation – though there is clearly an urgent need to husband, control and conserve our water supplies over time. Recent studies have begun to speak more and more insistently about 'peak water', drawing an analogy with the argument about 'peak oil'. There is an undoubtedly catastrophist element to these discussions. We know that fossil fuels do have a tangible limit, although there are immense reserves still to be exploited – in Venezuela, Iran, Bolivia, Saudi Arabia for example; but the reality is that oil cannot be regenerated and that its available quantities are finite. Fracking has opened a new avenue of supply, but with consequences for the stability of the planet about which we still know very little, and with disastrous consequences for the water table which remain to be calculated, although a recent report in the United States indicates that the water used in the extraction process shows a level of benzene contamination that is 'off the charts'. The analogy between oil and water, however, does not apply, for one very simple reason. Water is a renewable resource – though with humanity's sometimes diabolical ingenuity, it is probably possible that it could be contaminated to such a degree that large numbers of people could be denied the most essential component of survival. One prediction has it, for example, that two-thirds of world's population will live in water-stressed conditions by 2025, if current consumption continues. But that will occur only to the extent that we allow the current system of production, with its uncontrolled and unregulated use of water, to continue. 'Peak water' is not the consequence of limited supply but of a specific pattern of use – and that is what has to be urgently addressed.

Six countries have between them half of the world's renewable fresh water: Brazil, Canada, Russia, Indonesia, China and Colombia. Some 14,000 cubic kilometres of water are in rivers; the Amazon, the Congo and the Orinoco hold 25 per cent of the total, but none of them are in areas that are easily accessible. River water that can easily be reached and used probably amounts to around 9,000 cubic kilometres. Boiled down to...