Drought

This is one of the most interesting Argus Leader pieces I've read in a long time.  The science involved is based on samples from Devil's Lake, North Dakota (a great ice fishing lake).  Excerpt:

If the past 2,000 years are any guide, the Upper Midwest is due for the worst drought since European settlement, worse than the "dirty '30s" or any other in modern memory, a new study says.

The study of microscopic creatures at the bottom of Devils Lake in North Dakota shows a reliable wet-dry cycle of about 95 years that goes back 1,000 years. That puts North Dakota, and probably an area from South Dakota to Kansas, on schedule for a crippling water shortage in the next few decades, say researchers from the Energy and Environmental Research Center in Grand Forks, N.D.

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The scientists were able to reconstruct history using microscopic lake creatures called diatoms, whose bodies are made mostly of silica. When they die, they settle to the bottom and remain in the sediment indefinitely.

Different species of diatoms prefer different water conditions, so researchers can discover how those conditions changed by looking at what kinds of diatoms are in the different sediment layers. In this case, they reconstructed the salinity of Devils Lake, which closely reflects how wet or dry the region was, Solc said.

For the past 1,000 years, they found an average of 95 years between droughts and wet periods. That diatom history agrees with other studies and even the oral history of the Crow Indian Tribe.

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The implications for the future are dire. Cities, power plants and farms could run out of water stored in underground aquifers, stunting the economy.