“If the wars of this century were fought over oil, the wars of the next century will be fought over water — unless we change our approach to managing this precious and vital resource.” Ismael Serageldin first gave this warning in 1995, a year before he helped found the Global Water Partnership. As the regional effects of climate change continue to ramp up, we’re seeing this prediction come true in many parts of the world.
Now a new study in the Proceedings of the National Academy of Science calculates humanity’s “water footprint.” Much like the carbon footprint used to determine an individual’s contribution to global warming through the burning of greenhouse gases, the concept of the water footprint is being used to measure and compare water usage by nations, industry and individuals.
The paper notes that “[t]he Earth’s freshwater resources are subject to increasing pressure in the form of consumptive water use and pollution. Until recently, issues of freshwater availability, use, and management have been addressed at a local, national, and river basin scale. The recognition that freshwater resources are subject to global changes and globalization has led a number of researchers to argue for the importance of putting freshwater issues in a global context.”
The authors cite some interesting, if not terribly surprising figures. The water footprint of the average American is 2,842 m3/y (i.e., cubic metres per year, where one cubic metre is equal to one thousand litres, or several hundred gallons). This is more than twice the global average of 1,385 m3/y, and close to three times the use of most Chinese or Indian consumers (1,071 and 1,089 m3/y, respectively).
However, just like one’s carbon footprint is determined by more than just how much gas one personally burns (i.e., the consumer products one buys may have high carbon costs due to both shipping and manufacturing, one’s electrical use may be tied into a carbon-producing grid through coal plants), one’s water footprint can’t simply be counted by a meter on one’s tap.
Water is required to produce many different kinds of food. Grain is particularly greedy for water, followed closely by meat. Dairy is surprisingly low.
Non-food consumer products also require water in the manufacturing process. Sometimes enormous amounts. Everything from production of construction materials to basic household goods use water. And when we say water is “used up” in the production of something, that can be, at times, literally true. Wastewater produced from some manufacturing processes is too polluted to be simply returned to water systems and used again. Water usage in the oilsands, for example, is intense, and essentially lost to additional use afterwards. Thus a nation’s water and carbon footprints are sometimes linked.
One of the important conclusions of the study is that national water conservation policies are incomplete, since they don’t take into account the movement of “virtual water” around the world. In a global economy, the people of one country are actually consuming water resources across the world (for example, Americans are consuming Chinese water) because of water consumption/pollution as a direct result of manufactured imports into the country.
The authors also note that rainwater is not always considered in water policy, yet rainwater is related through the water cycle to other sources both above and underground. And it is thus equally vulnerable to pollution, over-consumption and climate-related drought.
The data and tools described in this study could be of great use in informing water management across the world. Besides using (and renewing) our freshwater more carefully, there are some individuals and groups who are being creative in dealing with their water shortages. In Guatemala, which has been experiencing a drought, indigenous communities have begun using a technique called “fog-harvesting” to make up for rain shortfalls.
At Penn State, researchers have turned to the miracle tree, Moringa oleifera, as an easy and affordable way of purifying bacterial and sedimented water for human use. Hey, it’s cheaper than a water treatment plant. Expect to hear more and more about these kinds of technologies as time goes on and water scarcity becomes a more significant issue.
Unfortunately, expect militaries the world over to take a keener interest in “securing” water resources, as well. As time goes on, it will become ever more apparent that our cavalier water usage cannot be sustained.
Photo credit: Fir0002 under a GNU 1.2 License