Sporadic shutdown of North Atlantic deep water production during the Glacial–Holocene transition?

Abstract

Pulsations in the production of North Atlantic deep water (NADW) have been implicated in generating drastic climatic fluctuations during the Glacial–Holocene (G/H) transition^1–3. The stable isotope record of benthic foraminifera in high-resolution cores from the Norwegian Sea suggests that such pulsations did occur⁴. Although the question of exact timing (and mechanism) is still open there is little doubt that NADW pulsations were important in climatic history because the rate of NADW production influences the rate of advection of heat to the northern North Atlantic⁵. Here we report that a sporadic shutdown of NADW may be recognizable in deep-sea carbonates with normal (low) sedimentation rates. Hence the possibility arises that relatively short-lived events (∼1,000–2,000 yr) in deep circulation can be mapped over large areas of the sea floor, despite the detrimental effects of bioturbation on signal resolution.