Effect of the equatorial Pacific upwelling on atmospheric CO2 during the 1982‐1983 El Niño

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Abstract

The 1982‐1983 El Niño event perturbed the otherwise steady growth in atmospheric CO2 due to fossil fuel combustion. Compared to the recent average growth rate in atmospheric CO2 of about 1.5 ppm per year, the growth rate in late 1982 fell to about zero. During this strong El Niño event, additional sinks for atmospheric CO2 operated. By late 1983, the growth rate rebounded to above average, indicating the presence of new sources. To a large extent, the relative roles of the possible actors have eluded us. In this study, box models of the ocean‐atmosphere carbon cycle are used to isolate and estimate the effects of the collapse and return of the upwelling in the equatorial Pacific during an El Niño. The models capture the major trends during the El Niño for sea surface temperature, nutrients, and ΔpCO2. The drop in ΔpCO2 in the normally strong source of the equatorial Pacific can account for a partial amount (probably less than 30%) of the decrease in the growth rate in atmospheric CO2 centered around late 1982. The recovery to normal equatorial conditions plays an even smaller and nearly negligible role in any growth rate overshoot later in El Niño. Changes in the higher‐latitude oceans and disequilibrium in the terrestrial cycle of photosynthesis and respiration continue as major potential agents behind the perturbation.

Original languageEnglish (US)
Pages (from-to)267-279
Number of pages13
JournalGlobal Biogeochemical Cycles
Volume3
Issue number3
DOIs
StatePublished - Sep 1989

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Environmental Science(all)
  • Atmospheric Science

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