Geomorphological and environmental responses to rapid hydrological changes in the Atlas Mountains (Morocco) during the last 30,000 years

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The Western Mediterranean and the North African desert margin are hotspots of global warming that is likely to include increased heat stress, reduced precipitation and more frequent occurrence of droughts. Holocene and Last Glacial archives indicate centennial to millennial-scale changes of the Western Mediterranean hydro-climate, although dating inaccuracies, sensitive but different environmental response mechanisms of investigated parameters, and insufficient chronological resolution lead to many uncertainties.The major aim of our project is to develop the understanding of environmental sensitivities and responses to climatic variability in the zone of the Western Mediterranean-Saharan transition. The follow-up project will extend knowledge of palaeohydrology, palaeoecology and dust dynamics beyond the Holocene, including the Late Glacial and Last Glacial Maximum (LGM). We aim to recover continuous and well-resolved lacustrine sequences spanning the last 30 ka. We will improve understanding of abrupt environmental responses during Holocene Rapid Climate Changes (e.g. LIA, 4.2 and 8.2 ka), the Holocene-Late Glacial transition and LGM cooling events at centennial to millennial time-scales.We will establish a spatial focus on the Middle to High Atlas mountainous desert margin from the sub-humid Northeast to the semiarid Southwest. As a desert margin this zone is highly sensitive to precipitation changes as reflected in the dynamics of environmental systems. For the first time, we will apply a hydro-climatic gradient approach with an identical suite of multi-proxy techniques at centennial-scale resolution. Our objectives are:O1: to retrieve and date new lake sediment cores along the hydro-climatic gradient. We will focus on two lakes: Sidi Ali in the sub-humid Middle Atlas and Tislit in the semiarid High Atlas. We will apply 210Pb dating, 14C pollen and macrofossil dating, luminescence dating techniques and Bayesian age modelling.O2: to constrain past rainfall and evaporation regimes. We will identify lake level and hydro-climatic proxies using biological (ostracods, aquatic pollen) and biogeochemical parameters including TOC, carbonates and δ13C/δ18O on ostracods.O3: to quantify past variability in Saharan dust supply. We will apply grain size end-member modelling, element and trace isotopes analyses.O4: to document catchment-scale responses (vegetation, fire, erosion) to rapid climate changes. We will constrain shifts in plant available moisture and regional temperature through the development of new pollen and particulate charcoal records. Silici-clastic parameters will be used as proxies for soil erosion.O5: to apply for the first time a hydro-climatic gradient approach. We will use multi-proxy statistics for the detection of temporal and spatial variability in environmental and aeolian responses along the North Saharan desert margin.