Calibration of the ¹⁴C Record

Radiocarbon (¹⁴C) ages are converted, or calibrated, to the calendar timescale using a curve of ¹⁴C values derived from measurements of known-age material. The extension of calibration curves beyond the end of dendrochronologically dated tree-rings has been made using ¹⁴C measurements of U-Th-dated coral and foraminifera from both varve-counted and nonvarved sediments. Example calibrations are given for a single ¹⁴C age, a wiggle-match for a time series of tree-ring ¹⁴C ages, and a stratigraphic sequence of samples. Additional complexities such as variations in marine reservoir ages, marine carbon in the diet, and regional offsets require consideration. The potential for future refinements to the calibration curve is discussed.