A new hydrogen-isotope approach to understand North African monsoon changes in the Holocene (HYDRACENE)

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This project aimes at a better understanding of the hydrologic evolution of the North-West African monsoon system over the Holocene, in particular during abrupt climate changes, and resolving causal factors, such as shifts in the monsoonal rain belt due to sea surface temperature gradients and atmosphere-vegetation feedbacks. As a new scientific approach, we analyze the hydrological signal based on compound-specific hydrogen isotope compositions of plant lipids in marine sediments from North-West African key sites in high temporal resolution. These isotope analyses are complemented by detailed climate simulations, which include an explicit modeling of isotopic fractionations within the hydrological cycle and in leaf water. First project results reveal a very good agreement between isotope data and model results, both for a present-day spatial isotope gradient along the North-West African coast as well as for temporal isotope variations related to the Sahel drought during the last century. For the forthcoming project period we propose continuing this successful scientific work and extending our analyses towards Holocene climate variations. Modeling experiments will be performed for selected time-slices and sensitivity test will be conducted to unravel significant forcing factors. The outcome of this project will lead to improved insights into the occurrence of large-scale continental hydrologic changes in North-West Africa and their causal processes.