Deep-water temperature reconstruction of sediment core MD99-2334

Results indicate greatly reduced T(dw) in the deep Northeast Atlantic during the last glaciation until ~15 cal. ka BP, when T(dw) warmed abruptly to near-modern values in parallel with the onset of the Bølling-Allerød interstadial. Subsequently, Tdw reverted to cold glacial values between ~13.4 and ~11.4 cal. ka BP, in parallel with the Younger Dryas cold reversal and the H0 ice-rafting event. Similar millennial-scale T(dw) changes also occurred during the last glaciation.

Indeed, throughout the last ~34 cal. ka, millennial delta18O(dw) and T(dw) changes have remained well coupled and are linked with IRD pulses coincident with Heinrich events 3, 2, 1, and the Younger Dryas, when transitions to lower T(dw) and delta18O(dw) conditions occurred. In general, millennial T(dw) and delta18O(dw) variations recorded in MD99-2334K describe an alternation between colder, low-delta18O(dw) and warmer, high delta18O(dw) conditions, which suggests the changing local dominance of northern-sourced North Atlantic Deep Water (NADW) versus southern-sourced Antarctic Bottom Water (AABW).

The observed similarity of the T(dw) and GISP2 delta18O(ice) records would therefore suggest a common component of variability resulting from the coupling of NADW formation and Greenland climate. A link between Greenland stadials and the incursion of cold, low-delta18O(dw) AABW in the deep Northeast Atlantic is thus implied, which contributes to the relationship between Greenland climate and the millennial benthic delta18O(cc) signal since ~34 cal. ka BP.