Global nature of the Younger Dryas cooling event inferred from oxygen isotope data from Sulu Sea cores

THE Younger Dryas, an approximately 1,000-year-long return to near-glacial conditions, interrupted the glacial/Holocene climate transition during which most of the Northern Hemisphere ice sheets melted. Evidence for the Younger Dryas event has been found mainly in sediments from the North Atlantic Ocean and northwest Europe, and this has led to the idea that the event was caused by an injection of meltwater into the North Atlantic Ocean^1-3. This model, however, has been recently questioned in the light of coral-reef data on the rate of sea level changes during this transition⁴. Here we present high-resolution oxygen isotope records from benthic and planktonic foraminifera from two radiocarbon-dated cores in the Sulu Sea, showing that the Younger Dry as occurred synchronously in the surface and deep waters of the Sulu Sea and the northern Atlantic Ocean. By combining our results with other palaeoclimate data, we suggest that the Younger Dry as event was a global phenomenon, and we believe it to have been caused by low atmospheric CO₂concentrations.