The role of the ocean in driving the glacial reduction in atmospheric carbon dioxide remains an enigma. Several recent hypotheses have invoked a redistribution of oceanic alkalinity as a possible cause of the glacial-to-interglacial atmospheric pCO2 change [Boyle, 1988a, b; Broecker and Peng, 1989]. Here I attempt to use paleo-barium data derived from Ba/Ca of benthic foraminifera to reconstruct chemical changes in glacial Circumpolar Deep Water (CPDW). These new data indicate that glacial CPDW was enhanced in Ba by up to 20%, presumably due to the elimination of the low-Ba North Atlantic Deep Water (NADW) flux to the southern ocean. This change in Ba can be used to constrain changes in CPDW alkalinity due to circulation changes alone; the Ba data suggest glacial CPDW alkalinity was perhaps 20 to 25 &mgr;equiv/kg higher than in the modern ocean. Following the polar alkalinity hypothesis, this difference could account for about one-third of the pCO2 drop [Broecker and Peng, 1989]. The new Ba data further confirm the homogeneous deepwater distribution of Ba during the last glacial maximum. Of the three paleochemical tracers of circulation recorded in benthic foraminifera (Cd/Ca, &dgr;13C, Ba/Ca), the glacial Ba/Ca data appear to record the most marked reduction in the influence of nutrient depleted NADW in the deep oceans. ¿ American Geophysical Union 1993