UC Irvine

The Suess Effect is a gradual decrease of the 14C/12C ratio in tree rings from 1870 to 1950 that is attributed mostly to the burning of 14C- free fossil fuels for energy. In contrast, pre-nuclear bomb high-precision measurements of 14C/12C ratios in banded corals from the North Atlantic Ocean do not exhibit the expected Suess Effect. Instead, large biennial-to- decadal shifts in the 14C/12C ratios appear throughout the coral records. This pattern indicates that rapid pulses of increased mixing between surface and subsurface waters occurred in the North Atlantic Ocean during the past century.