|Mixed-layer deepening during Heinrich events: A multi-planktonic foraminiferal δ18O approach|
Rashid, H.; Boyle, E.A. (2007). Mixed-layer deepening during Heinrich events: A multi-planktonic foraminiferal δ18O approach. Science (Wash.) 317(5845): 10.1126/science.1146138
In: Science (Washington). American Association for the Advancement of Science: New York, N.Y. ISSN 0036-8075, more
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Proxies from Greenland ice cores and North Atlantic marine sediment cores document repeated extreme climate swings of a few decades to millennia, including Heinrich massive ice-rafting events (HEs). We have found similar oxygen isotope from mixed-layer and thermocline-dwelling planktonic foraminifera during HEs 0, 1, and 4, suggesting that three foraminiferal taxa calcified their shells at similar temperatures in a homogenized upper water column. This implies that the surface mixed layer was deeper during HEs. Similar deepening can be seen in a published dataset from the northern margin of the ice-rafted debris belt, implying that these deep mixed layers during HEs were widespread in the region. We suggest that an increase in storminess during HEs intensifies vertical mixing of meltwater from ice-rafting in the upper ocean.