Possibility of Climatically Induced Variations in the 14C and 13C Enrichment Patterns as Recorded by a 3000-Year-Old Norwegian Pine

Abstract

The secular patterns of Deltaand delta-13C measured in wood cellulose are compared with a palaeotemperature index published for the immediate growth region. 14C enrichment shows an overall decrease of ca 20 per mil (Delta) during the 18th and 19th centuries with shorter term (decade) variations superimposed on the general trend. Measured Delta values correlate significantly with the average mean summer temperatures and indicate a linear coefficient of ca -10.2 per mil C-1. Short-term variations in the natural concentration of 14C which are closely related to climatic change may reflect the latitudinal dependence for atmospheric mixing. The secular trend in delta-13C covers a range of 2 per mil but variations of this magnitude reflect influences other than those directly associated with climatic change, eg, possible assimilation of recycled biospheric CO2 during early life and post AD 1850 anthropogenic effects. No evidence was found to suggest a significant correlation between delta-13C and the mean atmospheric temperature during summer growth periods.