Characterization of the last deglacial transition in tropical East Africa: Insights from Lake Albert

Abstract

New biomarker analyses from Lake Albert, East Africa spanning ~15–9 ka show the most extreme, abrupt, multi-stage climate and environmental shifts during the last deglacial transition of anywhere in Africa. Records of hydroclimate expressed in compound specific δD values from terrestrial leaf waxes and a TEX86 paleotemperature record support multiple stages of pronounced drying and cooling from 13.8 to 11.5 ka and demonstrate the dynamic behavior of the low latitude tropics during the deglaciation. The vegetation response, illustrated by compound specific δ13C values and fossil pollen records, was an expansion of C4 grassland when the region was cool and arid. These results advance our understanding of a spatially and temporally complex regional response to global climate forcing, suggesting weakening of the Indian Ocean monsoon at the end of the Pleistocene that coincides with a minor decrease in the rate of the Atlantic Meridional Overturning Circulation (AMOC) and during a time of stepwise cooling in the northern high latitudes.