Multimedia Gallery
September 3, 2009
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A tree is cored in Alaska to retrieve its tree rings, which reflect historical temperatures.
Coring tree: A hemlock tree is bored by a researcher (T. Daigle) in south-central Alaska. The width of the annual rings of trees can be used to infer past changes in growing season temperatures.
Credit: Darrell Kaufman, Northern Arizona University.
Images credited to the National Science Foundation, a federal agency, are in the public domain. The images were created by employees of the United States Government as part of their official duties or prepared by contractors as "works for hire" for NSF. You may freely use NSF-credited images and, at your discretion, credit NSF with a "Courtesy: National Science Foundation" notation.
Additional information about general usage can be found in Conditions.
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