A Review of Abrupt Climate Change Events in the Northeastern Atlantic Ocean (Iberian Margin): Latitudinal, Longitudinal, and Vertical Gradients - Abrupt Climate Change: Mechanisms, Patterns, and Impacts - page 26

Plate 2. Vertical gradients in the upper water column at site MD95-2041 during MIS 2 [Voelker et al., 2009] and 4 [this
study]. Plots and foraminifer species are as in Plate 1.

of the core MD99-2339 during Heinrich stadial 4 (Figure 3).
Thus, a boundary again existed between 38°N and 40°N,
but this time, it was clearly the Subarctic Front. Percent
N. pachyderma (s) values during Heinrich event 11 reached
90% at site SU92-03 [Salgueiro et al., 2010] and 100% in
the Bay of Biscay [Toucanne et al., 2009]. So the Polar
Front still reached the Iberian margin but only in the north-
ernmost ( ≥ 43°N) section and was located farther to the north
than during the last glacial cycle.
For glacial MIS 8, data for core MD95-2040 exist only
between 253 and 266 ka. Within this interval, percent N.
pachyderma (s) levels exceeded 70% and reached 90% and

thus were in the range of those recorded during the Heinrich
stadials of the last glacial cycle. Conditions stayed cold for
an extended period (261.6 to >266 ka), lasting longer than a
typical Heinrich event. Long-lasting cold was also recorded
in the Bay of Biscay [Toucanne et al., 2009], mostly with
levels close to 100% N. pachyderma (s) and reminding of the
hydrographic conditions observed for the Heinrich stadials.
Within age constraints, this interval coincided with a Heinrich-
type ice rafting event recorded at Integrated Ocean Drilling
Program Site U1308 [Hodell et al., 2008], so that similar
forcing mechanisms and responses in the AMOC can be
assumed. The low benthic δ

13 C values recorded at sites