NOAA/WDS Paleoclimatology - Urvina Bay Radiocarbon and Oxygen Isotope Data for 1939-1954

We present seasonal D14C and d18O measurements from a Galapagos coral sequence that grew during the early 20th century. Our results show that both D14C and d18O values are correlated with sea surface temperature in the Niño 3.4 region and are indicators of El Niño/Southern Oscillation. There is a significant inverse correlation between D14C and d18O values when D14C is lagged by ~2 months, indicating that sea surface temperature changes precede upwelling changes at this eastern equatorial location. We find that cold season low D14C values were higher after the Pacific Decadal Oscillation (PDO) changed from a positive to a negative phase. Cold season high d18O values were significantly higher after the PDO shift, as well. These findings suggest that there are two sources of low D14C waters that upwell at the Galapagos, Subantarctic Mode Water and shallow overturning water from the subpolar North Pacific.