Tree rings tell tale of a 60-year drought
By: Jennifer Tramm
Issue date: 6/13/07 Section: News
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A recent project conducted in the basin by members of the UA Laboratory of Tree-Ring Research to reconstruct historic stream flow has expanded the known record to the year 762, more than doubling the length of information previously known about the area (about the year 1400), said Dave Meko, associated research professor at the lab.
Included in the findings is the discovery of a drought that lasted 62 years in the 1100s. During this time, the Colorado River was running at a level below normal, and thus the period was marked by a series of dry years.
This knowledge can now help water managers predict water flow and different ways to handle droughts when they occur, Meko said, which is particularly important because the area is currently in a drought.
"It's not enough to tell water managers it was dry for so long," Meko said, adding that they want to know how dry it was and what could tweak the climate system to cause such a long drought.
The lab's role in that dialogue is to give water managers the most accurate picture of climate variability, Meko said.
A tree ring measures one year of a tree's life. Measuring and observing these rings helps dendrochronologists, or tree-ring scientists, to more accurately determine things such as what the climate was like in a given location and how old an archaeological site is.
Tree rings can pinpoint an archaeological site down to the exact year, according to the tree-ring lab's Web site.
Tree-ring research gives people a long-term picture of climate change, rather than the relative snapshot of 100 years or so from the instrumental records, Meko said.
To get this larger picture, he said, the research team had to take core samples from living trees and match up the rings with samples of older, dead trees in a chain until it formed a record all the way back to 762.
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