Variations of Radiocarbon in Tree Rings: Southern Hemisphere Offset Preliminary Results

The Queen's University of Belfast, Northern Ireland and University of Waikato, Hamilton, New Zealand radiocarbon laboratories have undertaken a series of high-precision measurements on decadal samples of dendrochronologically dated oak ( Quercus patrea ) and cedar ( Libocedrus bidwillii ) from Great Britain and New Zealand, respectively. The results show a real atmospheric offset of 3.4 ± 0.6% (27.2 ± 4.7 14 C yr) between the two locations for the interval ad 1725 to ad 1885, with the Southern Hemisphere being depleted in l4 C. This result is less than the value currently used to correct Southern Hemisphere calibrations, possibly indicating a gradient in Δ 14 C within the Southern Hemisphere.