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 15

A Review of Abrupt Climate Change Events in the Northeastern Atlantic Ocean
(Iberian Margin): Latitudinal, Longitudinal, and Vertical Gradients

Antje H. L. Voelker

Unidade de Geologia Marinha, Laboratorio Nacional de Energia e Geologia, Amadora, Portugal
CIMAR Associate Laboratory, Porto, Portugal

Lucia de Abreu 1

Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, UK
Unidade de Geologia Marinha, Laboratorio Nacional de Energia e Geologia, Amadora, Portugal
CIMAR Associate Laboratory, Porto, Portugal

The Iberian margin is a key location to study abrupt glacial climate change, and
regional variability is studied combining published and new records. Looking at the
trend from marine isotope stage (MIS) 10 to 2, the planktic foraminifer data,
conforming to Martrat et al. [2007], show that abrupt events, especially Heinrich
events, became more frequent and their impacts stronger during the last glacial
cycle. However, there were two older periods with strong impacts on the Atlantic
meridional overturning circulation: the Heinrich-type event associated with termi-
nation IV and the one occurring during MIS 8 (269 to 265 ka). During Heinrich
stadials, the Polar Front reached the northern Iberian margin (approximately 41°N),
while the Arctic Front was located in the vicinity of 39°N. During all glacial
periods, there existed a boundary at the latter latitude, either the Arctic Front during
extreme cold events or the Subarctic Front during less strong coolings or warmer
glacials. Along with the fronts, sea surface temperature (SST) increased southward
by about 1°C per 1° latitude leading to steep SST gradients. Glacial hydrographic
conditions were similar during MIS 2 and 4 but much different during MIS 6. MIS
6 was a warmer glacial with subtropical waters reaching as far north as 40.6°N. In
the vertical structure, Greenland-type oscillations were recorded down to 2465 m
during Heinrich stadials, i.e., deeper than in the western basin, due to the admixing
of Mediterranean Out

ow Water. It is evident that latitudinal, longitudinal, and

1 Now at Camberley, UK.

Abrupt Climate Change: Mechanisms, Patterns, and Impacts
Geophysical Monograph Series 193
Copyright 2011 by the American Geophysical Union.
10.1029/2010GM001021

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