Ocean-atmosphere interconnections from the last interglacial to the early glacial: An integration of marine and cave records in the Iberian region

Abstract

This study explores the climatic variability in the Iberian Peninsula (IP) and its surrounding seas from 140 to 65 kyr BP. Marine sediment cores and cave speleothems are used to reconstruct changes in sea surface water conditions, deep sea current intensities and atmospheric moisture availability based on stable isotopes, trace elements, grain size and XRF-elemental analysis. Oxygen isotopes in both terrestrial and oceanic archives recorded a large-scale precessional climatic rhythm that suggests a common modulation. This signal is interpreted as changes of the isotopic composition in the rainwater source area that is later transmitted into the cave. In terms of millennial-scale variability, the records trace the sequence of events defined for the North Atlantic region. The marine records show an intense sea-surface freshening and cooling related to Heinrich Event 11. During the Last Interglacial (LIG), the sea surface temperature evolution was heterogeneous around the IP with gradients larger than those from today. The LIG ended earlier in the Cantabrian Sea than in the western Mediterranean Sea, which it was coincident with an accelerated aridification phase that marked the glacial inception in a Minorca speleothem at 116.5 kyr BP and preceding the GS25. This was the first of a series of stadials that punctuated the early glaciation and where the sea thermal gradient almost disappeared around the IP. These intense cooling during stadials led the development of drier but intense westerlies over southern European latitudes, reflected in a Pyrenees speleothem record, and favouring enhanced deep convection in the western Mediterranean Sea. In contrast to this stadial regional homogeneity among the studied records, the interstadials periods are distinguished by their rather heterogeneous patterns around the IP pointing to much complex ocean-atmosphere interconnections during warm intervals.