Radiocarbon ages were converted to calendar ages using Calib 5.1 IntCal (Reimer et al., 2004). Years B.P., years before A.D. 1950. By using the assigned stratigraphic age (converted to years B.P.), the contemporaneous age difference (Rsurf) between the atmosphere 14C age (calculated using IntCal04) and the measured 14C age of the surface marine sample (planktonic foraminifera samples) can be calculated. Error estimates for DR include lab error in 14C measurement, uncertainty in the 14C calibration curve, error in NGRIP age, and an estimate of error for picking midpoints/tephra layers based on sedimentation rates and modeled mixing intervals.