On the relation between atmospheric CO2 and equatorial sea-surface temperature

Associations between the sea-surface temperature (SST) in the eastern equatorial Pacific (0°-10°S, 180°-80° W) and changes in atmospheric CO₂ concentration have been examined. The CO₂ records at Mauna Loa and the South Pole of the Scripps Institution of Oceanography, and the shorter records of the Geophysical Monitoring for Climatic Change program at Barrow, Samoa, the South Pole and Mauna Loa, were used after the annual cycles and the growth due to fossil fuel emissions had been removed.

We find that warmer than average SST precedes above-average increases in CO₂ by about one season at Mauna Loa and two seasons at the South Pole. The shorter records at Samoa and Barrow support longer lags - 2 to 3 seasons at Samoa and 3 to 5 seasons at Barrow. The correlations and their lags change with time, however, there being periods of relatively high correlation associated with El Niño events and periods of lower correlation when El Niño is not present. Furthermore, there is a seasonal preference for these high correlations. At Mauna Loa, the change of CO₂ from (NH) fall to spring is better correlated with antecedent SST than the changes from spring to fall. At the South Pole, a similar pattern is found with a one-season shift.