While climate change is generally regarded as the most immediate environmental threat, some experts argue that we are much closer to a world water crisis. In the world today, 600 million people already face water scarcity, and it is estimated that between 2.7 and 3.2 billion people may be living in water scarce or water stressed situations within the next 20 years. Much of this threat is thought to be in third-world countries, but we are already seeing water crises arise closer to home, such as the current drought the American southwest is facing. A recent study has found that Lake Mead, the reservoir created by the Hoover Dam, could dry up completely within 13 years.
The looming water crisis is in part caused by changing precipitation patterns resulting from climate change, but increasing demand for and pollution of water by society are the main driving forces. As the population and economy grow, the amount of fresh water required from the environment increases, which first creates stress on available water from lakes and streams. A growing population and economy also generate more waste and inevitably lead to greater degrees of pollution in these same lakes and rivers from which water is drawn. In turn, increased consumption and increased pollution of surface waters lead us to increase consumption of groundwater to satisfy our demands. As a result, many aquifers are being rapidly depleted, especially under cities, which have lower surface permeability. The problem is further exacerbated by water loss from drainage basins in the form of exported bottled water and high water intensity crops.
One partial solution for water crises is the use of desalination plants that turn saltwater from the ocean into fresh water. These plants require large amounts of power, however, which can further exacerbate the problem if the power is generated in ways that will increase climate change. Furthermore, this solution does not provide a solution for inland regions facing water shortages. Finally, the intakes for desalination plants disrupt aquatic life on the ocean floor, and cannot provide natural ecosystems with the water resources needed to remain healthy. A truly sustainable approach to water will be centered on conservation, both in terms of consumption and the way we treat our aquatic ecosystems.