Why early-historical radiocarbon dates downwind from the Mediterranean are too early

Abstract

Several authors have claimed that radiocarbon dates in the Ancient Near East are too early. Herein, a hypothesis that might explain this is presented. Marine degassing of "old" carbon (i.e. 14C-deficient C), induced by upwelling of old subsurface water, has been observed, in modern times, to cause century-scale 14C ages in the surface atmosphere. A review of the Mediterranean Sea post-ice-age circulation concludes that the subsurface waters became very old, primarily due to millennia-long stagnation. It is hypothesized that as the stagnation ended, subsurface waters were brought towards the surface, where they degassed old carbon. Additionally, Anatolian dendrochronology is shown to not contradict the hypothesis.