Reports

A 2000-Year Tree Ring Record of Annual Temperatures in the Sierra Nevada Mountains

Science  05 Mar 1993:
Vol. 259, Issue 5100, pp. 1433-1436
DOI: 10.1126/science.259.5100.1433

Abstract

Tree ring data have been used to reconstruct the mean late-season (June through January) temperature at a timberline site in the Sierra Nevada, California, for each of the past 2000 years. Long-term trends in the temperature reconstruction are indicative of a 125-year periodicity that may be linked to solar activity as reflected in radiocarbon and auroral records. The results indicate that both the warm intervals during the Medieval Warm Epoch (∼A.D. 800 to 1200) and the cold intervals during the Little Ice Age (∼A.D. 1200 to 1900) are closely associated with the 125-year period. Significant changes in the phase of the 125-year temperature variation occur at the onset and termination of the most recent radiocarbon triplet and may indicate chaotic solar behavior.

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