When the Rivers Run Dry

My own hunch is that climate change is going to be a major issue over the next few decades, but we will experience it less through warming itself – changes in temperature – and more through changes to, if you like, the hydrological cycle. In other words, more droughts, longer droughts, occasionally more floods, rising sea-levels. In other words, it’s water that’s going to be the prism if you like through which we see and experience global warming. And if you add that to damage to our soils and the land around the world, which again is going to be exacerbated by water shortages, I think water becomes the focal point. I think many environmental issues are going to hit us most seriously through water shortages. — Fred Pearce

We learned of Fred Pearce’s book from an excellent podcast interview [MP3] by Tom Keene’s Bloomberg on the Economy. There are a number of reviews of the book — try this one at Salon, which begins:

Pearce, a longtime editor for New Scientist, who is now an environmental consultant for the magazine, calculates that it takes 40 gallons of water to grow the ingredients for the bread in a single sandwich, not to mention 265 gallons to produce a glass of milk and 800 gallons for a hamburger. And that’s just what’s for lunch. Don’t get him started on what you wear to this water-rich feast. Even a simple cotton T-shirt bearing some hopeful green slogan like “Save the Bay” is a huge water user. Pearce figures it takes 25 bathtubs-full of water to grow the scant 9 ounces of cotton for such a shirt.

Water is the ultimate renewable resource, literally falling from the sky back to earth after it evaporates. And since it’s so heavy and cumbersome to move great distances, it’s also a local resource. Yet, start quantifying the water embedded in foods and goods, the “virtual water” as economists call it, and water is fast becoming a global commodity like oil. There’s Brazilian water in the coffee beans grown for an American latte; there’s Pakistani water in the cotton in that T-shirt.

…If there are 650 gallons of water in a pound of cheddar cheese, is it futile to make small gestures like turning off the water when you brush your teeth in the name of saving it?

It helps with water bills, so it makes sense in that way. And it may make sense with local water resources, which may be constrained, just within a small town, or even a community.

At the global scale, no, it doesn’t make much difference. Most of the water that each one of us uses comes from the water used to irrigate the crops that we consume. That’s principally food, but not only. Cotton for our clothing is a major user of water around the world.

The irrigation water usage is about 2/3 of the global water consumption.

There is a good introduction to Pearce’s research in this interview by Jim Puplava at FinancialSense.com — quoted above. Another interview to read is at the California Literary Review — this excerpt discusses one of my favorite worries, the Yellow River:

You call the Yellow River in China, the “hanging river.” What does that mean and what is the potential for disaster?

For thousands of years, the Chinese have controlled the Yellow River as it crosses its floodplain on its last several hundred miles’ journey to the sea, by constraining it within artificial banks, levees. The idea is to prevent floods. But the river is the world’s siltiest and through time it deposits this silt on its channel bed, which rises higher and higher above the surrounding floodplain. The Chinese have kept the river on its course by raising the levees ever higher. Hence the term “hanging river”. But this is a “double-or-quits” strategy. Chinese history is peppered with disasters when the river breaks its levees and floods across the land. But the worst disaster happened deliberately, in 1938, during the Sino-Japanese war. To halt advancing Japanese troops Chinese generals dynamited the levees and flooded the land. The Japanese were only held up for a few weeks, but the floods were so great that almost a million Chinese died. It is said to have been the most destructive single act of war ever. And it took engineers ten years to put the river back into its old channel.Today the risks are if anything higher. A combination of persistent drought and rising demand for water for irrigation leaves the river virtually empty by the time it reaches the “hanging river” zone. That sounds comforting. But the slow, feeble river drops even more of its silt on its channel than before. So the hanging river has been rising ever higher (it is now in places 70 feet above the floodplain) and, despite constant levee raising, the capacity of the channel is diminished. The risk is that one year there will be major upstream floods that dams cannot contain, and the levees on the floodplain will once again be overwhelmed, with dreadful consequences. Chinese engineers have been trying to manage dams on the river so as to create an artificial flood to flush out some of the silt and increase the capacity of the channel. But this has had only limited success, however.