For more than two decades, coral skeletons have been used to reconstruct records of isotopic and chemical ratios in surface seawater (for reviews, see Druffel, 1997a; Gagan et al., 2000). Here I demonstrate how high precision 14C records (±3) reveal information regarding regional mixing of surface and subsurface waters. Climatic variability on many time scales (e.g. El Niño, Pacific Decadal Oscillation, and the North Atlantic Oscillation) are detected in the corals by small changes in Δ14C. Radiocarbon records in corals have also been used to reconstruct the input of fossil fuel CO2 into the subtropical and tropical regions of the Pacific and Atlantic Oceans.