Southern Ocean sediments reveal a spike in authigenic uranium 127,000 years ago, within the last interglacial, reflecting decreased oxygenation of deep water by Antarctic Bottom Water (AABW). Unlike ice age reductions in AABW, the interglacial stagnation event appears decoupled from open ocean conditions and may have resulted from coastal freshening due to mass loss from the Antarctic ice sheet. AABW reduction coincided with increased North Atlantic Deep Water (NADW) formation, and the subsequent reinvigoration in AABW coincided with reduced NADW formation. Thus, alternation of deep water formation between the Antarctic and the North Atlantic, believed to characterize ice ages, apparently also occurs in warm climates.

Supplement to: Hayes, Christopher T; Martínez‐García, Alfredo; Hasenfratz, Albin; Jaccard, Samuel L; Hodell, David A; Sigman, Daniel M; Haug, Gerald H; Anderson, Robert F (2014): A stagnation event in the deep South Atlantic during the last interglacial period. Science, 346(6216), 1514-1517