Figure 7: Investigation of the effect of variable ΔR on the calibrated age.

This example uses corals from Barbados^82,83 with both U-series and radiocarbon dates. U-series ages (red, filled squares) are recalculated assuming a closed system and the decay constants of Cheng et al.²⁹. Radiocarbon data are recalibrated using ΔR values: (left panel) of the original authors (dark blue, open circles); the original authors and a±100 year uncertainty (blue, filled circles); ΔR=0 (green, filled triangles) and preindustrial value of ΔR=−27±11 years derived from Reimer and Reimer (ref. 56) (orange, filled diamonds). In the right panel, the U-series ages are compared to the recalibrated radiocarbon ages using ΔR values from the model of Butzin et al.⁸⁴: ΔR=200±100 years using a Gaussian (blue, open circles) and uniform (blue, filled diamonds) distribution; ΔR=900±100 years using a Gaussian (dark blue, open circles) and uniform (green, filled diamonds) distribution; a variable ΔR (yellow, filled circles).