A DEEP DIVE INTO THE SOUTH PACIFIC OCEAN DURING THE LAST ICE AGE

Late Pleistocene ice ages transformed Earth’s surface and set the stage for the modern era. The drivers of these global climate shifts remain unclear, including the relative roles of insolation, atmospheric CO₂, and other factors. We present new deglacial benthic foraminiferal temperature records from the Southwest Pacific Ocean in the context of both terrestrial and marine paleo records. Collectively, the evidence points to rapid, synchronous warming at intermediate-water depths (~1 km) in both Northern and Southern Hemispheres ~18,000 years ago with no detectable lags (cal yr BP). The pattern and pace of these changes are consistent with the idea that the atmosphere may have driven changes that ultimately launched the planet out of the last ice age. A mechanism involving shifts in the position and strength of the austral westerlies provides an intriguing prediction that is assessed in light of our new ocean temperature records. Temperature records from deeper sites (1.6 and 2.5 km) in the Southwest Pacific Ocean are also paired with oxygen isotope records to estimate changes in seawater density and assess hypothesized links between ocean stratification and carbon storage.