Water Shortages Due To Climate Change
According to a new study 70 percent of counties in the United States may face climate change-related risks to their water supplies by 2050. The conclusions are based on climate modeling, predicted precipitation, historical drinking water consumption as well as water use by industry and for electrical generation. States at the highest risk include Arizona, California, Nevada and Texas as well as parts of Florida. Similar reports concluded that parts of Asia and South America would also face water shortages in areas that are supplied by melting ice caps and glaciers. The main points of these articles are that rising temperatures mean that not only will there be more rain and less snow in the mountains, but also that snow will melt earlier in the year, resulting in rivers and streams carrying more water, much earlier than normal. Therefore, in areas that are not capable of capturing this early snow melt will lose the water to the ocean. Areas that are dependent upon water from glaciers will also be affected by the high temperatures, especially developing countries if their water infrastructure is weak. In addition to the western United States and Canada, hard-hit regions include parts of Europe, South America west of the Andes, and much of central Asia from northern India across to China and Russia. About one-sixth of the world's population (over 1 billion people) inhabit these areas. The regions at risk also account for about a quarter of the world's economic output. Policy makers need to take all this information into consideration and begin preparing for this event by evaluating new types of infrastructure and new ways to use water resources more efficiently.
The city of San Francisco gets its water from snow melt stored in the Hetch Hetchy Reservoir. Los Angeles gets most of its water from the Colorado River, which relies on Rocky Mountain snowfall. Phoenix, Denver, and Salt Lake City all get all or most of their water from snowmelt. San Diego purchases water from the Sacramento River which is fed from the Sierra snow pack. The Fresno metropolitan area has traditionally pumped water from deep artesian wells, but as the aquifer drops and is polluted by agricultural chemicals, the close to a million people in this area have started to compete directly with agriculture for an increasing share of the melt water. Hotter drier summers also affect water availability by increasing the rate of evaporation from the reservoirs (it is currently estimated that about 10% of stored water is lost) at the same time that crops demand more water to survive.
This video link discusses possible water shortages on a local level, specifically in San Diego: http://www.youtube.com/watch?v=VzXkwJ5hcM8
Sources:
http://www.grist.org/article/u.s.-faces-climate-change-caused-water-shortages/
http://www.scidev.net/en/news/millions-face-water-shortages-due-to-climate-chang.html
http://news.nationalgeographic.com/news/2005/11/1121_051121_warming_water.html
Some changes in water usage will be needed to offset changes in supplies. There are still many things that can be done to reduce residential usage in the affected areas (efficient use indoors and less water intensive landscaping), but agriculture, which uses ~70% of the water, will need to seek ways of irrigating and using water more efficiently.
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