A 23,000-year record of surface water pH and PC[O.sub.2] in the Western Equatorial Pacific Ocean

The oceans play a major role in defining atmospheric carbon dioxide (C[O.sub.2]) levels, and although the geographical distribution of C[O.sub.2] uptake and release in the modern ocean is understood, little is known about past distributions. Boron isotope studies of planktonic foraminifera from the western equatorial Pacific show that this area was a strong source of C[O.sub.2] to the atmosphere between approximately 13,800 and 15,600 years ago. This observation is most compatible with increased frequency of La Nina conditions during this interval Hence, increased upwelling in the eastern equatorial Pacific may have played an important role in the rise in atmospheric C[O.sub.2] during the last deglaciation.