Four Climate Cycles of Recurring Deep and Surface Water Destabilizations on the Iberian Margin
Belen Martrat,1
Joan O. Grimalt,1*
Nicholas J. Shackleton,2
Lucia de Abreu,2
Manuel A. Hutterli,3,4
Thomas F. Stocker4
Centennial climate variability over the last ice age exhibits
clear bipolar behavior. High-resolution analyses of marine sediment
cores from the Iberian margin trace a number of associated changes
simultaneously. Proxies of sea surface temperature and water
mass distribution, as well as relative biomarker content, demonstrate
that this typical north-south coupling was pervasive for the
cold phases of climate during the past 420,000 years. Cold episodes
after relatively warm and largely ice-free periods occurred
when the predominance of deep water formation changed from northern
to southern sources. These results reinforce the connection
between rapid climate changes at Mediterranean latitudes and
century-to-millennial variability in northern and southern polar
regions.
2 Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK.
3 British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK.
4 Climate and Environmental Physics, Physics Institute, University of Bern, CH-3012 Bern, Switzerland.
Deceased.
* To whom correspondence should be addressed. E-mail: jgoqam{at}cid.csic.es
