Records of ice-rafted detritus (IRD) concentration in deep-sea cores from the southeast Atlantic Ocean reveal millennial-scale pulses of IRD delivery between 20,000 and 74,000 years ago. Prominent IRD layers correlate across the Polar Frontal Zone, suggesting episodes of Antarctic Ice Sheet instability. Carbon isotopes (delta(13)C) of benthic foraminifers, a proxy of deepwater circulation, reveal that South Atlantic IRD events coincided with strong increases in North Atlantic Deep Water (NADW) production and inferred warming (interstadials) in the high-latitude North Atlantic. Sea level rise or increased NADW production associated with strong interstadials may have resulted in destabilization of grounded ice shelves and possible surging in the Weddell Sea region of West Antarctica.

Quaternary Research 56 (2001) 191-198. doi:10.1006/qres.2001.2252Received by publisher: 2000-09-19Harvest Date: 2016-01-04 12:20:38DOI: 10.1006/qres.2001.2252Page Range: 191-19

Quaternary Research 52 (1999) 369-380. doi:10.1006/qres.1999.2072Received by publisher: 1999-05-14Harvest Date: 2016-01-04 12:20:38DOI: 10.1006/qres.1999.2072Page Range: 369-38

[1] The last glacial to interglacial transition was studied using down core records of stable isotopes in diatoms and foraminifera as well as surface water temperature, sea ice extent, and ice-rafted debris (IRD) concentrations from a piston core retrieved from the Atlantic sector of the Southern Ocean. Sea ice is the first variable to change during the last deglaciation, followed by nutrient proxies and sea surface temperature. This sequence of events is independent of the age model adopted for the core. The comparison of the marine records to Antarctic ice CO 2 variation depends on the age model as 14 C determinations cannot be obtained for the time interval of 29.5-14.5 ka. Assuming a constant sedimentation rate for this interval, our data suggest that sea ice and nutrient changes at about 19 ka B.P. lead the increase in atmospheric pCO 2 by approximately 2000 years. Our diatom-based sea ice record is in phase with the sodium record of the Vostok ice core, which is related to sea ice cover and similarly leads the increase in atmospheric CO 2 . If gas exchange played a major role in determining glacial to interglacial CO 2 variations, then a delay mechanism of a few thousand years is needed to explain the observed sequence of events. Otherwise, the main cause of atmospheric pCO 2 change must be sought elsewhere, rather than in the Southern Ocean.