Interglacial Climate Over the Last 1 Ma in the SW Iberian Margin

The Iberian Margin is a key location to understand major past climatic and oceanographic changes because it is very sensitive to high and low latitude processes. We combine the MD01-2443/4 with new data from Site U1385 "Shackleton site" (37°34.285'N, 10°7.562' W, at 2587 mbsl), recovered during IODP Expedition 339, to present the long-term evolution of Sea Surface Temperature (alkenone derived) on the Iberian Margin over the last 1 Ma. This record shows a clear and strong linkage between the Iberian Margin SST and insolation forcing, ultimately controlled by the Earth's orbital parameters. Interglacials are characterized by surface water temperatures close to 20°C throughout the last 1 Ma, with the warmest temperatures occurring during interglacial MIS 5e and MIS 19, whereas coldest interglacial was recorded during MIS 23. The SST record from the Iberian Margin shows no evidence for the "luke warm" interglacials observed in Antarctic ice cores beyond 400 ka. On the Iberian Margin, interglacials were equally warm before and after 400 ka despite relatively low CO2 concentrations such as during MIS 15, 17 and 19. Furthermore, interglacials over the last 1 Ma exhibit complex structure, including some cases of multiple warm periods separated by abrupt and significantly cold episodes. These episodes occurred mainly during glacial inceptions which are climatically unstable periods marked by strong millennial-scale fluctuations in SST linked to freshwater input. Terminations at the Iberian margin show more abrupt and higher amplitude SST oscillations from MIS 22 to 17 (Termination X, IX and VIII) than after MIS 17. This period (from 900 to 650 ka) is a critical period of the Mid Pleistocene Transition that coincides with the onset of strong glaciations in the North Atlantic.