Evidence from the high-latitude North Atlantic for variations in Antarctic Intermediate water flow during the last deglaciation.

We present evidence that the characteristic chemical signature (based on coupled benthic foraminiferal\ud Cd/Ca and d13C) of Antarctic Intermediate waters (AAIW) penetrated throughout the intermediate depths\ud of the Atlantic basin to the high-latitude North Atlantic during the abrupt cooling events of the last\ud deglaciation: Heinrich 1 and the Younger Dryas. AAIW may play the dynamic counterpart to the ‘‘bipolar\ud seesaw’’ when near-freezing salty bottom waters from the Antarctic (AABW) sluggishly ventilate the deep\ud ocean. Our data reinforce the concept that interglacial circulation is stabilized by salinity feedbacks\ud between salty northern sourced deep waters (NADW) and fresh southern sourced waters (AABW and\ud AAIW). Further, the glacial ocean may be susceptible to the more finely balanced relative densities of\ud NADW and AAIW, due to either freshwater input or a reversal of the salinity gradient, such that the ocean\ud is poised for NADW collapse via a negative salinity feedback. The unstable climate of the glacial period\ud and its termination may arise from the closer competition for ubiquity at intermediate depths between\ud northern and southern sourced intermediate waters