The link between the El Nino-El Viejo cycle and changes in the concentration of atmospheric carbon dioxide is investigated by comparing CO2 anomalies, sea surface temperature and sea level (SL) from 1959 to 1993. A correlation is shown to exist between variations in SL and CO2 anomaly. SL in the eastern Pacific lags CO2 by about 2 months, whereas SL in the central Pacific leads CO2 by 1-2 months. El Nino and El Viejo are defined using SL at Galapagos Island. El Nino events often account for minima in the CO2 anomaly whereas the El Viejo events more often account for maxima. Relatively large changes in CO2 can occur during rapid transitions between these two extremes of ENSO. We hypothesize that the 1991-93 El Nino was the cause of stalled CO2 growth after 1990 and that its recent termination will result in a rapid return to the previous upward trend in atmospheric CO2.
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