Ask students: What is drought? Elicit or explain that drought is a prolonged period of abnormally low rainfall.
Explain that California is facing an historic drought. The drought is in its fourth year, and scientists suggest that it's the worst in 1200 years. 2014 was the driest year in California since records have been kept (200 years). About 90 percent of the state is in "severe drought" and 40 percent in "exceptional drought."
The mountain snowpack, which melts in spring and feeds the rivers and streams and fills the reservoirs, is just 5 percent of its normal height. The reservoirs themselves are at 65 percent of their normal volume. NASA estimates that California needs 11 trillion gallons of water to end the drought.
Until recently, the state was asking for voluntary water conservation. On April 1, 2015, Governor Jerry Brown announced California's first mandatory water restrictions. The rules require cities, businesses, farms and property owners to reduce their water use. Water for private lawns, golf courses, and cemeteries will be restricted.
This drought is controversial in at least four ways.
1. Farm vs City
Question: What percentage of water used in California is used for agriculture?
Though agriculture accounts for 80 percent of water use in the state, virtually all the mandatory water restrictions apply to urban districts. Farms are required to develop plans for conservation, but no specific requirements were announced. The drought has already cost California farmers $1.5 billion and led to 17,000 farmworkers losing their jobs.
2. Almonds vs. Broccoli
Question: Which requires more water to grow: a pound of almonds or 10 pounds of broccoli?
Answer: A pound of almonds requires as much water as 56 lbs. of broccoli.
Almonds are a controversial crop, because they require an enormous amount of water and account for 10% of all water used in California. Every pound of shelled almonds requires about 2100 gallons of water to grow. That’s in the range of beef, which requires up to 2500 gallons of water per pound. Activists working for a more sustainable economy make the case that meat production is so inefficient that it is unsustainable.
3. Surface water vs Underground water
True or False: Supplies of underground water are replenished by water from the surface of the earth.
Answer: Yes and no. The deeper sources of water will never be replenished.
In times of drought, farmers look for water underground. In normal years, 40 percent of California's water comes from underground sources; with the drought, it's 60 percent. These underground reservoirs (or aquifers) are being used up at a rate that is not sustainable. Wells that used to supply water at 500 feet now don’t produce water till they reach a depth of 1000 feet.
4. People vs. the Earth
True or False: Global climate change makes droughts worse.
True: Warmer temperatures increase the rate of evaporation and decrease the snowpack, which feeds the rivers and reservoirs. There is some evidence that California’s recent weather pattern, which produces little precipitation, is the result of human-caused climate change.
California has faced droughts throughout history--many worse than the present one. Two facts make this drought different. First, droughts are made worse by higher temperatures. With temperatures rising because of human-made carbon emissions (global climate change), scientists predict longer and drier droughts in the coming years. Second, past civilizations survived mega-droughts in part because their numbers were so small. Today, 38 million people live in an area that might not have enough water for them.
- Should California cut back on the amount of water farms can use? Should farmers change some of their crops to those using less water?
- Some people propose raising the price of water. Is this a good idea?
- Long-term sustainability will probably involve a drastic reduction in animal farming. Can you live without hamburgers?
- How might California's drought affect the rest of the country?