“A single Northern Hemisphere calibration curve has formed the basis of radiocarbon dating in Europe and the Mediterranean for five decades, setting the time frame for prehistory,” Manning and co-authors write. “However, as measurement precision increases, there is mounting evidence for some small but substantive regional (partly growing season) offsets in the same-year radiocarbon levels.”
A recent study suggests that the current basis for radiocarbon dating in the Middle East may be relying on an erroneous calibration based on sources outside of the Middle East. This site also reports on the study and includes a video on radiocarbon dating.