Three Myths about Water t is all about the WATER. It is not global warming that will wake the U.S. up to climate change. (They rather like the warmer temperatures in Minnesota.) Instead, it will be the extremes in water resources that will shake our denial. Let us examine three myths about water that expose the myopia.
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Myth #1. Water is a Static Resource Wrong. Most of the U.S. experienced significant increases in precipitation and streamflow (and decreases in drought) during the second half of the 20th century (The Effect of Climate Change on Agriculture, Land Resources, Water Resources and Biodiversity, The U.S. Climate Change Science Program, 2009; www.climatescience.gov/Library/sap/sapsummary.php). That is what prompted Milly et al. (Science 2008, 319, 573-74) to comment, “Stationarity is dead.” Statistical norms from 100 y records at gauging stations are not completely worthless, but the magnitude and frequency of extreme events is changing so rapidly that one does not have much certainty, say, to map 100 y flood plains and to plan communities. In general, arid areas are getting drier and humid areas are getting wetter over the entire planet. The average person thinks climate change is something that egghead scientists prognosticate for the distant future, like the year 2100. But it is real now. People are living with a changing water environment right now. Intense precipitation events (defined as the heaviest 1% of all events) have increased 31% in the Midwest and 67% in the Northeast U.S. in the past 50 y (Global Climate Change Impacts in the United States, U.S. Global Change Research Program, 2009; www. globalchange.gov). It is raining more, and the streamflow is amplified further by rapid runoff (low evapotranspiration and recharge). Floods are the clearest manifestation of this climate change and floods make a strong impression on people. If there’s a record flood in Bangladesh, we may think that is climate change. But when there’s a record flood inundating your own home, that is a freaking disaster.
Myth #2. Water is a Renewable Resource Not really. Not in the way we are using it. The term “renewable” implies continual replacement of a damaged or decaying resource. That connotes a limitless resource, but it is really not. Groundwater resources are a poignant example. We are overpumping groundwater worldwide, and recharge rates are not sufficient to replenish the aquifers. In the U.S., the poster child for groundwater mining is the Ogallala (High Plains) Aquifer which runs from 1516 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / March 1, 2010
South Dakota down to the panhandle of Texas. It once contained the equivalent water of Lake Huron, ∼1% of the world’s available freshwater (in lakes). But the Ogallala has been pumped-down 15-30 m (50-100 ft) in places and has begun to drain the hydraulically connected Republican River. The Republican River runs through Colorado, Nebraska, and Kansas and it, too, is being depleted every step of the way. Ironically, federal farm payments and corn-ethanol subsidies pay (indirectly) to mine a precious natural wonder, the Ogallala. And it is not only unconfined aquifers like the Ogallala, which are threatened. Confined aquifers like the Cambrian-Ordovician unit in the Midwest are also in jeopardy. Municipalities west of Chicago have pumped it down 244 m (800 ft), amounting to a loss of storage and pressure in the system that can only be recharged through decades to centuries. Surprisingly, it is not the overuse of nonrenewable resources that is most glaringly unsustainable in this world. It is the overuse of “renewable resources” which become depleted by unsustainable practicesslike the mining of groundwater, contamination of surface waters and sediments, overfishing of seas, and clear-cutting of forests.
Myth #3. We Can Always Desalinate the Ocean for More Water Unlikely and very costly. It will require massive amounts of energy and will generate enormous volumes of brine to desalinate seawater. Singapore is a city-state of 4.6 million people who catch and utilize every drop of precious water that falls on their island. Still, they need to import about half of all their water supply from Malaysia. In the face of such water insecurity, Singaporeans made a plan 20 y ago to build a water industry that would be a model for the world, while simultaneously solve their own water shortages. They planned to build five new desalination plants using brackish groundwater or seawater as a source, but a funny thing happened on their way to water independence: They discovered it was far cheaper to reuse wastewater (both industrial and domestic) and to treat it thoroughly to drinking water standards, rather than to employ desalination of seawater. In the future, nations will routinely reuse wastewater through advanced treatment, aquifer and reservoir storage and recovery, while employing both direct and indirect potable reuse. Careful management of the entire water cycle is the key to husbandry of our precious water resource. World Water Day is March 22. U.N. Deputy Secretary-General Asha-Rose Migiro has reminded us, “More than 1.4 billion people live in river basins where their use of water exceeds minimum recharge levels, leading 10.1021/es100264g
2010 American Chemical Society
Published on Web 02/08/2010
to desiccation of rivers and the depletion of groundwater.” As population continues to grow and as glaciers melt, there will be more widespread and more desperate shortages of water. In The Immense Journey, noted essayist Loren Eiseley wrote, “If there is magic on this planet, it is contained in water.” Let’s hope we can overcome the myths and use water sustainably as the magical resource that it is.
Jerald L. Schnoor Editor*
[email protected] March 1, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 1517
