Interhemispheric Anti-phased Climate Changes During the Last Deglaciation

We have obtained a high-resolution oxygen isotopic record of cave calcite from Gruta Do Padre (PAD), central Brazil. The chronology was determined by 20 U-Th ages from 2 stalagmites. Tests for equilibrium conditions show that oxygen isotopic variations are primarily caused by climate change. We interpreted the PAD record, spanning the last 16 thousand years, in terms of meteoric precipitation changes at this low-latitude location. The oxygen isotopic profile shows clear abrupt millennial-scale variations with amplitudes as large as 3 per mil. Using independent age scales, we compare the record to contemporaneous records from caves in eastern China and high latitude ice cores. During the last deglaciation, PAD calcite δ18O anti-correlates remarkably with δ18O in the Hulu Cave (Wang et al., 2001, Science), indicating that precipitation histories at the two sites are anti-phased, similar to our previous observations from southern Brazil speleothems. As Greenland temperature has been shown to correlate with Hulu precipitation, PAD precipitation anti-correlates with Greenland temperature. The timing of the main transition at PAD is synchronous within error with the Hulu and Greenland records. For instance, the rapid PAD transitions into a dry "Bolling-Allerod", and the beginning and the end of a wet "Younger Dryas", occur at about 14620±60 yr B.P., 12750±60 yr B.P., and 11600±100 yr B.P., respectively. Such anti-correlations support the bipolar see-saw mechanism through the last glacial-interglacial transition. However, the millennial-scale climate variability probably involves both ocean thermohaline and atmospheric circulation changes.