Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates

Considerable work has gone into developing high-precision radiocarbon (¹⁴C) chronologies for the southern Levant region during the Late Bronze to Iron Age/early Biblical periods (∼1200-600 BC), but there has been little consideration whether the current standard Northern Hemisphere ¹⁴C calibration curve (IntCal13) is appropriate for this region. We measured ¹⁴C ages of calendar-dated tree rings from AD 1610 to 1940 from southern Jordan to investigate contemporary ¹⁴C levels and to compare these with IntCal13. Our data reveal an average offset of ∼19 ¹⁴C years, but, more interestingly, this offset seems to vary in importance through time. While relatively small, such an offset has substantial relevance to high-resolution ¹⁴C chronologies for the southern Levant, both archaeological and paleoenvironmental. For example, reconsidering two published studies, we find differences, on average, of 60% between the 95.4% probability ranges determined from IntCal13 versus those approximately allowing for the observed offset pattern. Such differences affect, and even potentially undermine, several current archaeological and historical positions and controversies.