Comprehensive analysis of Atlantic Circulation during Heinrich-Event 1 & 2

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The dynamic of the Atlantic Meridional Overturning Circulation (AMOC) is one of the key players in the global climate system. It crucially influences the redistribution of heat and carbon from surface into the deep sea and vice versa. Therefore, assessing the sensitivity of the AMOC is a major challenge for paleoclimatology. Here the focus is set on how excessive freshwater input through melting of continental ice can affect its overturning vigour and, hence, heat supply to high northern latitudes. Such forcing can be tested by investigating its behaviour during extreme iceberg discharge events into the open North Atlantic during the last glacial period, so called ¿Heinrich-Events¿. In recent years numerous studies have provided a wealth of 231Pa/230Th measurements in marine sediments, successfully demonstrating the important value of this tracer for the reconstruction of the natural variability of the AMOC. In this project we measure Pa/Th in numerous sediment cores across Heinrich events 1 and 2 thus strongly augmenting the available database of Pa/Th for the investigation of the Atlantic Ocean deep circulation studies. These measurements are accompanied by the determination of the biogenic opal content of the sediment samples. Strength and geometry of the AMOC before, during and after the Heinrich-Events 1 and 2 can be derived from this new database in an inverse model approach. By this we are aiming for answering the question if Heinrich-Events either caused cessations of AMOC or if maybe in contrast Heinrich-Events are the result of AMOC changes. Thus, in the context of potential ice shield melting and increasing precipitation in the northern North Atlantic, Heinrich-Events may display a model scenario improving our understanding of the upcoming response of AMOC on climate changes.