Radiocarbon/ tree-ring calibration, solar activity, and upwelling of ocean water.

Abstract

Least-squares fitted smooth curves to radiocarbon versus tree-ring calibration data for the period AD 1140 to 1950 are compared with climatic warming and cooling of the North Atlantic (Little Ice Age), and with recorded sunspot numbers over the period AD 1670 to 1950. Calibration curves from different parts of the globe are not identical, and appear to be determined by a combination of variable solar activity and variable oceanic upwelling of (super 14) C-depleted water, with the variable upwelling itself partly determined by solar activity.