March 18, 2014



Scott: The West has been struggling after years of drought scorched by soaring temperatures and a historic dry season. But a group of scientists are looking to the past in order to come up with clues for the future. Tom Hanson has the story.

Tom: From crops to livestock to land, to say the least, years of drought are taking a toll on California and other western states.

During California’s wet season, the water should rise to this point on this tree. This is a watermark where, typically, this part of the tree is submerged underwater when the reservoir is full.

California is the driest it has been in more than 400 years. The drought started three years ago but new research shows it could last a lot longer.

Lynn Ingram: Historically, if we go back several thousand years we’ve seen that droughts can last over a decade and, in some cases, they can last over a century.

Tom: Scientist Lynn Ingram uses sediment cores, samples of layers of earth and rock, to study the history of drought in the West. She says we could be in for a mega-drought, a dry period that can last for decades. And Ingram and her team of scientists from UC Berkeley are finding evidence of these dry periods in San Francisco Bay. To do the tests, they remove the sediment from the bay and nearby marshes.

Ingram: What you notice is that the vegetation shifts to more salt-tolerant type vegetation.

Tom: Which means plants are adapting to a lack of freshwater. And tree rings on ancient stumps show the same, narrow rings during decades of drought. Some trees have no rings at all.

Ingram: These patterns tend to repeat themselves. I mean we can expect that this will happen again.

Tom: Scientists now believe the 20th century was one of the wettest in more than a thousand years. During that time, we built massive dams, rerouted rivers, we used water to build major cities and create a $45 billion agriculture industry in a place that used to be a desert. Water has led our country to prosper and it is something we have depended heavily on in modern times. Even after heavy rains in the past weeks, the drought continues. And Ingram believes California should be prepared for a 100-year dry period.

Tom Hanson, Channel One News.


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