A Multiproxy Paleoclimate Reconstruction over the Last 250 kyr from Marine Sediments: The Northwest African Margin and the Western Mediterranean Sea

Abstract

Marine sediments are one of the best archives of past climate change because they are essentially continuous in character and their age can be determined relatively easily. The study of grain-size and geochemical composition of marine sediments off the shore of the Northwest (NW) African margin and in the western Mediterranean during the past years has shed some light on the forcing mechanisms for dust input and wind strength in the North Canary Basin, and the climatic teleconnections between high and low latitudes during the glacial--interglacial transitions. On an orbital scale, the records show that changes in insolation associated with precession and eccentricity cycles are the major drivers in controlling dust input to the North Canary Basin. A particular response is observed during glacial terminations when maxima in productivity and grain-size are detected as a likely consequence of subtropical anticyclonic circulation intensification due to higher insolation but lower sea surface temperature (SST) over the North Atlantic. Then, the strengthened trade winds forced upwelling and had the ability to carry coarser particles at terminations. On a millennial timescale, Saharan dust variations appear to be strongly related to periods of strengthened atmospheric circulation in high northern latitudes, that is Dansgaard-Oeschger (D/O) cold stadials. Therefore, the study of marine sediments off the coast of NW Africa and in the Alboran Sea provides evidence of changes in climate and landscape distribution on land during the last 250 kyr that can be useful for understanding the origin of human populations and the patterns of their dispersal out of Africa ca. 50 ka.