This month I had the pleasure of hearing Lester Brown (environmental analyst and founder of both the Worldwatch Institute and the Earth Policy Institute) speak at a Population Connection board meeting. Many of his remarks centered around energy resources but interestingly enough, rather than climate change, Brown sees aquifer depletion as the largest threat to the earth and its population.

Aquifers are underground layers of rock that can store large amounts of water. Storing water in aquifers, whether it is there naturally or was pumped in, is far more efficient than storing it in reservoirs because aquifer water does not evaporate.

Around the world aquifers are a crucial source of water for drinking and irrigation yet many countries are depleting them faster than they can be replenished. As aquifer resources are exploited, pumping water becomes more costly and requires more energy because the water is farther underground. As of 2005, nearly half of the world’s population (over 3.2 billion people at that time) lived in countries that were overpumping aquifers. Today the situation is even more dire. Consider the following information about aquifer depletion:

• In Iran, citizens are abandoning villages as wells run dry from overpumping, resulting in a stream of “water refugees.”
• The Indian state of Tamil Nadu is home to over 62 million people. The irrigated farmland in the state has been cut in half over the last decade, as decreasing water tables have caused 95% of wells owned by small farmers to run dry.
• Due to lower water levels, some areas in China are pumping water from as deep as 300 meters (almost 1,000 feet) underground, an expensive undertaking that is impacting wheat production in the country.
• In addition to increased prices, drilling deeper to reach the lowering water table also creates land subsidence, which is when the ground compacts and drops lower due to a lack of structural support from water. In the United States, land subsidence has caused hundreds of millions of dollars in damage to states such as California, Florida, and Texas.

Aquifer depletion is already a significant issue facing the global population, and it is an issue that will be exacerbated by climate change and population growth.

Brown, L. (2013). Aquifer depletion. Retrieved from http://www.eoearth.org/view/article/150159