ENSO-like Forcing on Oceanic Primary Production During the Late Pleistocene

ENSO-like Forcing on Oceanic Primary Production During the Late Pleistocene

Luc Beaufort, Thibault de Garidel-Thoron, Alan C. Mix, Nicklas G. Pisias

Science, Vol 293, Issue 5539, 2440-2444 , 28 September 2001

[DOI: 10.1126/science.293.5539.2440]

Late Pleistocene changes in oceanic primary productivity along the equator in the Indian and Pacific oceans arerevealed by quantitative changes in nanoplankton communities preserved in nine deep-sea cores. We show that variations in equatorial productivity are primarily caused by glacial-interglacial variability and by precession-controlled changes in the east-west thermocline slope of the Indo-Pacific. The precession-controlled variations in productivity are linked to processes similar to the Southern Oscillation phenomenon, and they precede changes in the oxygen isotopic ratio, which indicates that they are not the result of ice sheet fluctuations. The 30,000-year spectral peak in the tropical Indo-Pacific Ocean productivity records is also present in the Antarctica atmospheric CO₂ record, suggesting an important role for equatorial biological productivity in modifying atmospheric CO₂.