After watching the news last night, I decided to pull out these paragraphs from a book I started back in the 1990s at the insistence of a gentleman named Jim Starry. The book was entitled “Simple Solutions” and it was based on Starry’s engineering ideas and innovations. This excerpt is somewhat dated, of course, but it’s part of the intro to his material on filtration systems and the global supply of water.
Approximately 100,000 cubic miles of water evaporates each year from the Earth’s surface, 85% of it from the ocean. And that’s the easy part to comprehend. What happens next becomes our economic and political issues. What happens, of course, is that water returns to Earth in a frustratingly natural, highly heterogeneous, manner, that is, according to wind currents, latitudes, geographic features such as land masses and mountain ranges, and season. In turn, this heterogeneity dictates and distributes variations in agricultural economies, heavy industrial economies, energy and power utilization, navigation, public health, climax vegetation, recreation, tourism, cultural phenomena, including art and literature, and natural disasters.
About 1/4 of a cubic mile of this water is, at any one time, currently tied up in human bodies. This figure would not be a particularly impressive one were it not for the fact that about 5 trillion gallons of water flows through us each day, collectively, which converts into about 2 quadrillion gallons a year, a figure that will double in the next century. And that’s only in terms of urine. As with all natural resources, however, humans use water indirectly, and in a global economy, they use it globally. Water is similar to oil, lumber, and metals, in that our consumption of them leaves a footprint on Earth, but our individual footprint is scattered in many countries and takes many forms. The last time someone ate a banana in Brooklyn, for example, he or she used water that fell somewhere in Latin America. And during the course of a typical day that same person baths, brushes teeth, flushes a toilet, drinks pop which is mostly water, eats foods grown under irrigation and cooked in water, puts on clothes that have been through the laundry, and does many other seemingly routine acts that consume water directly or indirectly.
Scaling up our individual water use to that of a nation gives anyone a peek into Jim Starry’s thoughts. A truly simple calculation will likely show that if everyone who brushed his or her teeth in the United States turned off the water instead of letting it run, as a nation we’d save at least a hundred million gallons a day. To a person whose daily thoughts span hundreds of millions of years and square miles, society’s seeming pre-occupation with the immediate is always a little bit frustrating. If Jim Starry has any advice to science teachers around the world, it would be to give your best efforts to this task of teaching us to think in large scales and long terms. Or at least to translate our daily experiences into those of all humanity, those of our children, and those of our grandchildren. Tricks to accomplish this seemingly daunting task are as numerous and freely accessible as our ideas. A trip to the grocery stores produces apple, orange, and grapefruit counts and measurements. A thirty minute squeeze job, or a weigh-in before and after drying, produces an estimation of the water content of common fruit. The scale up is a simple lesson in ecological arithmetic; the phone book yellow pages lets a sixth grader estimate how much water is tied up in oranges on any one day in his or her city.
But the amount of water actually tied up in fruit is only the tip of a very large iceberg. For example, in the early 1980s, world citrus production was about 50 million tons per year, 35 million of which were oranges and tangerines. Citrus groves covering about 7 million acres. About half of this production occurs in North and Central America and around the Mediterranean. In the San Joaquin Valley of California, where in the middle 90s irrigation water cost between $60 and $100 per acre-foot, mature orange groves yielded about 547 cartons per acre, a typical acre supporting 110 trees. Each tree gets 10 gallons an hour when the irrigation system is operating. These estimates, as well as the following, are from a U.S. Cooperative Extension bulletin for 1995, entitled “Sample costs for establishing an orange orchard and producing oranges (low volume irrigation),” available on the web.* Up to the time of a tree’s maturity, however, i.e. the first three years, there are no oranges per acre; in the 4th year the harvest is something less than 30 cartons per acre, and in the 5th slightly over 200 per acre, until the mature yield is achieved. Irrigation costs range from about $30 per acre for first year trees, up to about $94 per acre at maturity. Frost protection, including water, would be another $164 per acre for mature trees. Drip irrigation systems depreciate at $63/acre/year, and interest on the irrigation systems can be expected to run about $43/acre/year.
How does a sixth grade teacher in Idabel, Oklahoma, or Gallup, New Mexico, convert all these cooperative extension data into an ecological arithmetic lesson Jim Starry would approve of? Easy. Walk down to the local store, go back to the produce department, and ask one of the people working back there how many oranges there are in a carton. That one number lets anyone who can multiply and divide at elementary school level to calculate not only how much water is in an orange, but how much water it took to get that small amount of water stored in a form (orange) it could be shipped around the world. I promise; trust me: do the calculations yourself, and you’ll never look at another orange with quite the same naiveté as before. Suddenly apples, grapefruit, tomatoes, bananas, grapes, in fact all fruits and vegetables, will also look different. What will they look like? They’ll look like a gigantic water problem for the next millennium.
See also TEN MINUTE ECOLOGIST and INTELLIGENT DESIGNER: EVOLUTION FOR POLITICIANS both available as paperbacks from createspace and as e-books from kindle and smashwords.