STABLE ISOTOPES IN TREE-RING CELLULOSE AND CLIMATIC-CHANGE

Relationships between the stable isotope contents (delta-H-2, delta-C-13) in dendrochronologically dated tree rings of firs (Abies alba, Black Forest) and air temperature, relative humidity, as well as precipitation rate were investigated for the period 1959 to 1980. Only the late wood of each ring was used, since isotope data from early wood, grown during spring, does not unambiguously reflect the climate of the respective growth season. The delta-C-13-values, but not the delta-H-2-values show significant correlations with temperature, humidity, and precipitation. Based on this observation, delta-C-13-values were used to construct a paleoclimatic record for the past millenium. This required correction for anthropogenic C-13-inputs since about 1850. The reconstructed temperatures are largely in agreement with presently-accepted variations in the recent past, whereby a "climatic optimum" appears during the Early Middle Ages with August temperatures about 0.5-degrees-C higher than today.