Fresh Water Impacts: Threatened Drinking and Irrigation Water from Regional Drying and
Saltwater Intrusion
Scientists predict that changes in precipitation, saltwater intrusion into fresh water reservoirs, higher temperatures, and other
impacts of global warming will have major impacts on regional water resources (Fankhauser, 1995, p. 40; IPCC, 1995b, p.
6). In some areas, greater precipitation will lead to excess runoff, erosion, and flooding; in others, less precipitation, increased
evaporation, and reduced winter snowpack will dramatically reduce water supplies. In each case, the costs to society will
likely be enormous.
While they were not necessarily the result of global warming, recent floods illustrate the devastating impacts that too much
water can place on economies — and lives. For example, the Midwest flood of 1993 surpassed all previous U.S. floods in
terms of precipitation amounts, record river stages, flood duration, persons displaced, crop and property damage, and
economic impact (CEQ, 1995, p. 59). Flood damages in the nine affected states were an estimated $15.6 billion, and at least
38 people died as a direct result of the flooding. Even Western states that are usually stricken with drought could face their
share of floods (CEQ, 1995, p. 60). The 1993 winter floods in the Southwest yielded damages of $392 million ($228.9 million
in Arizona and $163.7 million in California), and led to 17 deaths. If global warming continues, such losses could become
much more commonplace.
Droughts can also have serious economic and social implications. The potential economic impacts alone are significant.
Decreased water supplies will affect agriculture, fisheries, recreational opportunities, and the ability of river barges to transport
goods efficiently. For example, low flow conditions in the Mississippi River during the 1988 drought brought barge traffic to a
halt, disrupting the movement of numerous commodities including coal, agricultural chemicals, and petroleum products, causing
economic losses of millions of dollars (Glantz, 1988, p. 243). And years of drought in California have contributed to numerous
fires, including the 1991 fire in Oakland that destroyed 3,000 homes, killed 25 people, and caused an estimated $1.5 billion in
damages (Smithsonian Institution, 1994, p. 110). If the frequency and severity of droughts increases as a result of global
warming, the costs will be much higher. A recent study on the effects of global warming in California suggests that a 30 percent
decrease in stream flows could cause direct economic damages amounting to over $225 million per year by the year 2020
(Knox, 1991, p. 82).
The impacts of reduced water supplies will go well beyond the dollar costs. Poor countries, in particular, will likely face
substantial social and environmental costs as the frequency and severity of droughts increases. In developing countries, severe
drought is often accompanied by malnutrition and starvation. For example, the persistent drought of the 1980s in the Sahelian
region of Africa caused millions of deaths and brought tens of millions more to the brink of starvation (McMichael, 1993, p.
151). Droughts have also led to considerable civil strife. As precipitation patterns shift due to global warming, and as
population growth places additional strains on water resources, the impacts will likely be devastating.
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