In 1956, Shell Oil geologist M. King Hubbert presented a paper to the American Petroleum Institute in which he argued that United States oil production would hit its all-time highest rate of production sometime between 1965 and 1970.

Though widely derided at the time, Hubbert’s prediction turned out to be correct: U.S. oil production peaked in 1970, at roughly 9.6 million barrels of oil per day. Today the United States produces only about 5.3 million barrels per day, a decline of nearly 40 percent, even as consumption has continued to rise. To meet the demand, the U.S. has been forced to import ever larger quantities of crude oil from overseas, with profound consequences for foreign policy, global security and sustainability.

Today, a growing number of scientists argue that global peak oil may be upon us—an argument that would seem to be supported by the increasingly heroic measures oil companies are taking (such as the ultra-deepwater drilling in the Gulf of Mexico) to keep up with global oil demand. Given the world’s dependence on oil, a global production decline has enormous implications.

Until recently, Hubbert’s modeling techniques were applied only to oil and other non-renewable resources. But in the last few years, researchers of other resources have begun to examine whether consumption of some renewable resources follows Hubbert’s model.

So how useful is the concept of “peak water”?

Noted water expert Dr. Peter Gleick of the Pacific Institute, spoke on the issue at the Columbia Water Center last February.

The World's Water Crisis- Peak Water and Moving to a Sustainable World from Earth Institute on Vimeo.

As Dr. Gleick makes clear, there are important differences between fresh water and crude oil. Practically any use of oil, he says, is “consumptive” – that is, once the energy in it is extracted and used, its quality is degraded and it is effectively gone forever. Water, on the other hand, is never really lost to the hydrologic cycle. Thus it is not literally possible to experience global “peak water”.

But insofar as water is extracted from a particular stock faster than nature can replenish it, the potential for regional peak water is very real. Many underground aquifers and even some surface water stored in lakes and glaciers can indeed be thought of as non-renewable—and thus subject to peak and decline–because they can be depleted faster than the natural recharge rate.

Gleick also introduces the concept peak “ecological” water – the point past which a watershed’s water supply is depleted to the point of causing irreversible damage to local ecosystems that depend on it. The history of human-caused desertification attests to the very real dangers of irresponsible regional water use.

Finally, in peak oil circles, researchers often speak not of the “the end of oil” but of “the end of cheap, easy to access” oil. Looked at from this perspective, the global water situation is indeed analogous to that of oil.

The end of cheap, easy oil is here. The end of cheap, easy water is here too. Now what are we going to do about it?