Narrator: This is Science Today. Oceanographers and meteorologists from the University of California, San Diego 's Scripps Institution of Oceanography are traveling further inland to better understand the climate system. In the Sierra Nevada mountain range, these scientists are studying old trees because records of growth in tree rings provide clues to long-term natural cycles of drought and heavy rains. Dr. Wolf Berger, a professor of oceanography at Scripps, says historical weather records have not provided very much information.
Berger: The problem, especially here on the West coast, is that are records are not very good. That what people have measure and what they have written down usually goes back fifty years in any detail and maybe a hundred years with less detail. And that we'd really like to know what things are like over 200 year period, 300 year period – maybe over a thousand years.
Narrator: The researchers can take samples from living trees known to be sensitive to weather change by using thin cores that can be bored without hurting the tree. For Science Today, I'm Larissa Branin.