Detection of El Nino and decade time scale variations of sea surface temperature from banded coral records: implications for the carbon dioxide cycle.
Stable oxygen isotope ratios from annually banded corals are correlated with historical records of sea surface temperature in the central and eastern tropical Pacific ocean. El Nino events between 1929 and 1976 are detected using this method, but there are discrepancies between the records of El Ninos from corals and those determined using historical hydrographic and meteorologic data. The average annual description of delta 18O during El Nino events is greater at the Galapagos Island sites (0.45per mille) than at the Fanning and Canton Island sites in the mid-Pacific (0.20-0.30per mille and less than 0.2per mille, respectively). Of prime importance is evidence of decade time scale variability of sea surface temperature (SST) in the tropical Pacific. In particular, annually averaged SST appears to have been 0.5o-1oC higher in the eastern tropical Pacific during the 1930's than during subsequent years. A significant net flux of CO2 from the surface ocean to the atmosphere is envisioned during these periods of higher SST.-Author