Oxygen Isotope Ratios in Trees Reflect Mean Annual Temperature and Humidity

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Science  27 Mar 1981:
Vol. 211, Issue 4489, pp. 1417-1419
DOI: 10.1126/science.211.4489.1417


Values of the oxygen isotope ratios18O) in tree-ring cellulose closely reflect the δ18O values in atmospheric precipitation and hence mean annual temperature. The change in δ18O in cellulose is 0.41 per mil per degree Celsius for selected near-coastal stations. The values of δ18O in precipitation and cellulose also change with altitude, as demonstrated for Mount Rainier, Washington. A temperature lapse rate of 5.2° ± 0.5°C per 1000 meters calculated from cellulose δ18O values agrees with the accepted mean annual lapse rate of 5°C per 1000 meters for this region. Cellulose δ18O values and δ18O values of carbon dioxide equilibrated with leaf water differ by a fixed 16 per mil.