On May 27 2010 I posted on an excellent article in the Economist involving threats society faces with respect to water resources; see
Today, I want to highlight another article in the same issue. The article is
For want of a drink [subscription required]
The entire article with its figures is worth reading. Indeed, this article should be required reading in any introductory class in water resources and in climate. Examples of the valuable summary presented in this article include
Water is indeed scarce in many places, and will grow scarcer. Bringing supply and demand into equilibrium will be painful, and political disputes may increase in number and intensify in their capacity to cause trouble. To carry on with present practices would indeed be to invite disaster.
Why? The difficulties start with the sheer number of people using the stuff. When, 60 years ago, the world’s population was about 2.5 billion, worries about water supply affected relatively few people. Both drought and hunger existed, as they have throughout history, but most people could be fed without irrigated farming. Then the green revolution, in an inspired combination of new crop breeds, fertilisers and water, made possible a huge rise in the population. The number of people on Earth rose to 6 billion in 2000, nearly 7 billion today, and is heading for 9 billion in 2050. The area under irrigation has doubled and the amount of water drawn for farming has tripled. The proportion of people living in countries chronically short of water, which stood at 8% (500m) at the turn of the 21st century, is set to rise to 45% (4 billion) by 2050. And already 1 billion people go to bed hungry each night, partly for lack of water to grow food.
Scarce or plentiful, water is above all local. It is heavy—one cubic metre weighs a tonne—so expensive to move. If you are trying to manage it, you must first divide your area of concern into drainage basins. Surface water—mostly rivers, lakes and reservoirs—will not flow from one basin into another without artificial diversion, and usually only with pumping. Within a basin, the water upstream may be useful for irrigation, industrial or domestic use. As it nears the sea, though, the opportunities diminish to the point where it has no uses except to sustain deltas, wetlands and the estuarial ecology, and to carry silt out to sea.
The emphasis on water has an essential resource supports and reinforces the viewpoint that we are emphasizing in the new set of books to be published by Elsevier in which I am Editor in Chief (more on this in later posts). I presented this perspective in my blog post
where I wrote
“There are 5 broad areas that we can use to define the need for vulnerability assessments : water, food, energy, health and ecosystem function. Each area has societally critical resources. The vulnerability concept requires the determination of the major threats to these resources from climate, but also from other social and environmental issues. After these threats are identified for each resource, then the relative risk from natural- and human-caused climate change (estimated from the GCM projections, but also the historical, paleo-record and worst case sequences of events) can be compared with other risks in order to adopt the optimal mitigation/adaptation strategy.”
A set of articles in the Economist on the other four resources (food, energy, health and ecosystem function) would be very valuable.