Stationarity is Dead. What’s Next?

Stationarity is not the kind of word you hear in every day conversation, yet an article in the Feb 1, 2008 issue of Science caught my attention when it proclaimed in tall block letters, Stationarity is Dead. It also said that stationarity was a casualty of climate change, and the death of stationarity requires an entirely new approach for water management.

Stationarity turns out to be “the idea that natural systems fluctuate within an unchanging envelope of variability.” To put it another way, stationarity says that water supplies will vary from year to year, but the average supply and the standard deviation in supply will remain constant.

This article asserts that climate change has changed all this. The average supply, and the standard deviation in supply, are both shifting. It is even pointless to think of these parameters as constants.

If this view is correct, this has enormous consequences. Water infrastructure in the U.S. is massive – think dams, reservoirs, wells, canals, pumping stations, treatment facilities. It is also incredibly expensive and much of it needs to be replaced. This poses difficult scientific and political-economic questions. On the one side, can we develop theories and tools for predicting future water supplies? On the other, can we redesign traditional institutions and infrastructure so that they will better serve our needs in a changing world?