01347nas a2200205   4500000000100000000000100001008004100002260001800043100001800061700001700079700002400096700001900120700002000139700001900159245009900178856006000277300001200337490000800349520078400357       2007                            d  cJuly 27, 20071 aBelen Martrat1 aJoan Grimalt1 aNicholas Shackleton1 aLucia de Abreu1 aManuel Hutterli1 aThomas Stocker00aFour Climate Cycles of Recurring Deep and Surface Water Destabilizations on the Iberian Margin  uhttp://www.sciencemag.org/content/317/5837/502.abstract  a502-5070 v3173 aCentennial 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.