Monday, June 17, 2013

Peak Water and Food Bubbles

The concept of peak oil has been much discussed over the past several decades. Less note has been taken of the concept of "peak water." Whereas peak oil was related to an anticipated depletion of the total supply of oil, peak water is a more nuanced concept. Peter Gleick provides a discussion in an article on Is the U.S. Reaching Peak Water? 

"To be clear, "peak water" doesn’t mean the U.S. or the world is running out of water. Overall, there is plenty of water on the planet and it is (mostly) a renewable resource. But there are serious physical, environmental, and economical constraints on water availability that make regional water problems increasingly urgent."

Gleick provides three categories of water usage to illustrate different issues: peak renewable water, peak non-renewable water, and peak ecological water. The first concerns surface or rapidly-renewed subsurface water supplies.

"For a number of major river basins, we have reached the point of peak renewable water limits, including the Colorado River in the United States. All of the water of the Colorado (indeed, more than 100% of the average flow) is already spoken for through legal agreements with the seven US states and Mexico and in a typical year river flows now often fall to zero before they reach their ends. This is true for a growing number of rivers around the world."

The nonrenewable category refers to sources that are accessible, but for geologic reasons are effectively non-rechargeable. Usage of these sources ultimately leads to depletion and increased costs for extraction.

"This kind of unsustainable groundwater use is already occurring in the Ogallala Aquifer in the Great Plains of the United States, the North China plains, parts of California’s Central Valley, and numerous regions in India. In these basins, extraction may not fall to zero, but current rates of pumping cannot be maintained. Worldwide, a significant fraction of current agricultural production depends on non-renewable groundwater. This is extremely dangerous for the reliability of long-term food supplies."

Water use affects not only humans, but all of nature.

"By some estimates, humans already appropriate almost 50% of all renewable and accessible freshwater flows, leading to significant ecological disruptions. Since 1900, half of the world’s wetlands have disappeared. The number of freshwater species has decreased by 50% since 1970, faster than the decline of species on land or in the sea. The term "peak ecological water" refers to the point where taking more water for human use leads to ecological disruptions greater than the value that this increased water provides to humans."

Gleick suggests that the US has already exceeded "peak" conditions in all three categories. He provides this supporting data:

Water use peaked over 30 years ago. One must conclude that if more water could have been economically extracted from the environment, it would have been.

Gleick is interested in business and investment issues. He sounds an alarm by indicating the potential risk to food supplies from over-extraction of water, but finishes on a high note by pointing out that even though water usage has leveled off, our economy has continued to grow. In other words, water productivity has continued to increase and it is not yet clear that water availability has been a hindrance to the economy.

Lester R. Brown, president of the Earth Policy Institute, is directly concerned with the security of the world’s food supply in his book Full Planet, Empty Plates: The New Geopolitics of Food Security. He is greatly concerned about the tendency to use water in an unsustainable manner because the ability to produce food is tied to the water supply. If water usage is unsustainable, then food production is unsustainable. He refers to such a condition as living in a "food bubble."

"We live in a world where more than half the people live in countries with food bubbles based on overpumping. The question for each of these countries is not whether its bubble will burst, but when."

Brown provides this list of the "bubble" countries.

Note that most countries in the Middle East make his list. The causes and political ramifications of food shortages in that region have been discussed in Climate change, Food security, and Revolution.

Brown provides a short summary of the water/food supply issues in the major countries. A measure of a country’s capability to utilize water supplies to produce food is its ability to increase or maintain land under irrigation.

"In most of the leading U.S. irrigation states, the irrigated area has peaked and begun to decline. In California, historically the irrigation leader, a combination of aquifer depletion and the diversion of water to fast-growing cities has reduced the irrigated area from nearly 9 million acres in 1997 to 8 million acres in 2007. In Texas, the irrigated area peaked in 1978 at 7 million acres, falling to some 5 million acres in 2007 as the thin southern end of the Ogallala aquifer that underlies much of the Texas panhandle was depleted."

In China, Brown is concerned about the long-term health of agriculture in the North China Plain, an area that produces half of its wheat and a third of its corn. The region receives little rainfall and is dependent on groundwater.

"China has had ample warning. A groundwater survey done more than a decade ago by the Geological Environment monitoring institute (GEMI) in Beijing found that under Hebai Province, in the heart of the North China Plain, the average level of the deep aquifer dropped 2.9 meters (nearly 10 feet) in 2000. Around some cities in the province, it fell by 6 meters in that one year alone."

"....concerns are mirrored in the unusually strong language of a World Bank report on China’s water situation that foresees ‘catastrophic consequences for future generations’ unless water use and supply can quickly be brought back into balance."

Of most concern to Brown is India, a country of over a billion in population that is barely able to feed its people today, yet is expected to add another half billion before its population tops out.

"In this global epicenter of well drilling, where farmers have drilled 21 million irrigation wells, water tables are dropping in much of the country....The wells, powered by heavily subsidized electricity, are dropping water tables at an accelerating rate. In North Gujarat, the water table is falling by 6 meters, or 20 feet, per year. In some states half of all electricity is now used to pump water."

"In communities where underground water sources have dried up entirely, all agriculture is rainfed and drinking water is trucked in. Tushaar Shah, a senior fellow at the International Water Management Institute, says, ‘When the balloon bursts, untold anarchy will be the lot of rural India’."

Brown expresses this fear:

"For the world as a whole, the near simultaneous bursting of several national food bubbles as aquifers are depleted could create unmanageable food shortages."

And he leaves us with this ominous note:

"Underlying the urgency of dealing with the fast-tightening water situation is the sobering realization that not a single country has succeeded in arresting the fall in its water tables."

A declining water supply competes with soil erosion, desertification, population growth, global warming, and diversion of food stocks to fuel as threats to world food security. Brown’s book was intended to warn us of the danger of following such an unsustainable path.

"Scientists and many other concerned individuals have long sensed that the world economy had moved onto an environmentally unsustainable path....It now seems that the most imminent effect will be tightening supplies of food. Food is the weak link in our modern civilization—just as it was for the Sumerians, Mayans, and many other civilizations that have come and gone. They could not separate their fate from that of their food supply. Nor can we."

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