We can cut carbon emissions by one third by replacing fossil fuels with renewable energy sources for electricity and heat production." –Lester R. Brown, Janet Larsen, Jonathan G. Dorn, and Frances Moore, Time for Plan B: Cutting Carbon Emissions 80 Percent by 2020
Chapter 4. Emerging Water Shortages: Introduction
Africa’s Lake Chad, once a landmark for astronauts circling the earth, is now difficult for them to locate. Surrounded by Cameroon, Chad, Niger, and Nigeria—all countries with fast-growing populations—the lake has shrunk 96 percent in 40 years. The region’s soaring demand for irrigation water coupled with declining rainfall is draining dry the rivers and streams that feed the lake. As a result, Lake Chad may soon disappear entirely, its whereabouts a mystery to future generations. 1
The shrinkage of Lake Chad is not unique. The world is incurring a vast water deficit—one that is largely invisible, historically recent, and growing fast. Because the deficit comes largely from aquifer overpumping, it is often discovered only when wells go dry.
This global water deficit is the result of demand tripling over the last half-century. The drilling of millions of irrigation wells has pushed water withdrawals beyond recharge rates, in effect leading to groundwater mining. The failure of governments to limit pumping to the sustainable yield of aquifers means that water tables are now falling in countries that contain more than half the world’s people, including the big three grain producers—China, India, and the United States. 2
Beyond these traditional sources of water insecurity, climate change is now affecting water supplies. Rising temperatures are boosting evaporation rates, altering rainfall patterns, and melting the glaciers that feed rivers during the dry season. As the glaciers melt, they are threatening to convert perennial rivers such as the Ganges in India and the Yellow in China into seasonal rivers, increasing both water and food insecurity. With the earth’s climate system and its hydrological cycle so intertwined, any changes in climate will alter the hydrological cycle. 3
Among the more visible manifestations of water scarcity are rivers running dry and lakes disappearing. A politics of water scarcity is emerging between upstream and downstream claimants both within and among countries. Water scarcity is now crossing borders via the international grain trade. Countries that are pressing against the limits of their water supply typically satisfy the growing need of cities and industry by diverting irrigation water from agriculture and then importing grain to offset the loss of productive capacity.
The link between water and food is strong. We each drink on average nearly 4 liters of water per day in one form or another, while the water required to produce our daily food totals at least 2,000 liters—500 times as much. This helps explain why 70 percent of all water use is for irrigation. Another 20 percent is used by industry, and 10 percent goes for residential purposes. With the demand for water growing in all three categories, competition among sectors is intensifying, with agriculture almost always losing. While most people recognize that the world is facing a future of water shortages, not everyone has connected the dots to see that this also means a future of food shortages. 4
1. U.N. Environment Programme (UNEP), Africa’s Lakes: Atlas of Our Changing Environment (Nairobi: 2006); M. T. Coe and J. A. Foley, “Human and Natural Impacts on the Water Resources of the Lake Chad Basin,” Journal of Geophysical Research (Atmospheres), vol. 106, no. D4 (2001), pp. 3349–56; population information from U.N. Population Division, World Population Prospects: The 2006 Revision Population Database, at esa.un.org/unpp, updated 2007.
2. Water use tripling from I. A. Shiklomanov, “Assessment of Water Resources and Water Availability in the World,” Report for the Comprehensive Assessment of the Freshwater Resources of the World (St. Petersburg, Russia: State Hydrological Institute, 1998), cited in Peter H. Gleick, The World’s Water 2000–2001 Production, Supply and Distribution, electronic database, at www.fas.usda.gov/psd/psdonline, updated 11 June 2007. (Washington, DC: Island Press, 2000), p. 52; grain production from U.S. Department of Agriculture (USDA),
3. Emily Wax, “A Sacred River Endangered by Global Warming,” Washington Post, 17 June 2007; Clifford Coonan, “China’s Water Supply Could be Cut Off as Tibet’s Glaciers Melt,” The Independent (London), 31 May 2007.
4. Jacob W. Kijne, Unlocking the Water Potential of Agriculture (Rome: U.N. Food and Agriculture Organization (FAO), 2003), p. 26; water use from Shiklomanov, op. cit. note 2, p. 53
Copyright © 2008 Earth Policy Institute