Tundi Agardy, Ph.D.
Freshwater as a resource
Freshwater is one of the most important provisioning services the planet’s ecosystems provide mankind. Drinking water is necessary to sustain life, of course, but so too is water needed to provide sanitation, irrigate crops, tend livestock, sustain freshwater aquaculture, support industry, and generate electricity. Contemporary withdrawal uses 25% of the continental run-off to which the majority of the population has access each year2. However, only 15% of the global population lives in relative water abundance, and that figure will drop as population pressures mount and water-overuse threatens renewable water sources.
Demand for potable water is on the rise as the world population approaches 7 billion; clean and sanitary water supplies are increasingly in short supply and are leading to serious conflict in many parts of the world. The World Bank estimates that one quarter of the world’s low income population lacks adequate access to freshwater (20 liters of dependable water per day), while 1.1 billion people do not have access to clean drinking water3. The annual health burden on the global population caused by inadequate water, sanitation, and hygiene is 1.7 million premature deaths and loss of more than 50 million years of life4.
Water quality is less important an issue for agriculture, within limits. Contaminated water supplies used to irrigate food crops can cause serious disease outbreaks, and farm animals can fall prey to water-borne diseases. Conversely, water quantity is the main issue for other uses of freshwater, such as for energy generation or transport, although sediment pollution does impact hydropower operations.
As freshwater supplies dwindle and water wars erupt in arid hot-spots around the globe, desalination of seawater is increasingly looked to as an alternative source of water. However, desalination has significant environmental, as well as substantial economic, costs. A recent report suggests that desalination capacity will increase 61% worldwide between 2006 and 2010 and a total of 140% by 2015. Most of the growth in capacity will occur in the Middle East and northern Africa, but capacity will also increase in China, India, Australia, Spain, the U.S., and even the U.K.5
Reports analyzing desalination at the global scale, throughout the U.S., and in California suggest that the operations may contribute significantly to greenhouse gas emissions and may have dramatic ecological impacts due to the release of large quantities of brine laced with water treatment chemicals6. A recent report by the National Academy of Sciences (US) urges caution in the development of new desalination facilities, and outlines key avenues of research that should be undertaken before desalination is scaled up to meet our ever-increasing water needs.
2 Millennium Ecosystem Assessment (MEA). 2005 Ecosystems and Human Well-Being. . Ch. 7 Fresh Water. Island Press, Washington p 167
3 World Health Organization/UNICEF 2004. Meeting the MDG Drinking Water and Sanitation target: A Midterm Assessment of Progress. WHO Geneva
4 MEA (2005) p 195
5 Kristin, C. 2008. Environmental costs of desalination. Environmental Science &Technology 41(16) :4837
6 WWF. 2007. Making water: Option or distraction for a thirsty world? WWF Gland, Switzerland; National Research Council (US) 2008. Desalination: A National Perspective. National Academies Press, Washington, DC; Cooley, H., P.H. Gleick and G. Wolff. 2006. Desalination, with a grain of salt: A California perspective. Pacific Inst. Available at http://www.pacinst.org/reports/desalination/desalination_report.pdf
