Varying climate and human activity altered the Baltic Sea ecosystem and left their footprint in the physical, biological and chemical properties of its sediments. Particularly, the partly fine-laminated sediments from the deep basins are valuable archives of these changes, because of their sub-decadal resolution.

Understanding the processes behind the recorded environmental changes requires (i) knowledge about their temporal progression, i.e. the exact timing of the succession of changes within an event and the time-span from event to event, and (ii) to put them in a regional to hemispheric context. This knowledge is for Baltic Sea sediments presently hampered due to centennial-scale chronological uncertainties. Therefore, utilizing the down to sub-decadal environmental information in deep Baltic Sea sediments necessitates their placement in an improved chronological framework. Globally common production rate variations of the cosmogenic radionuclides ¹⁰Be and ¹⁴C can provide a novel tool for constructing such a framework.

A pilot ¹⁰Be time-series covering the Mid-Holocene enabled the synchronization of Baltic Sea sediments from the Western Gotland Basin to the absolute dated ¹⁴C production record from the IntCal20 calibration curve. This alignment reduced the existing centennial chronological uncertainties to ± 10-15 years.

Within this proposal, we aim at the establishment of a continuous decadal-scale ¹⁰Be record from sediments of the Western Gotland Basin, as well as its alignment to the atmospheric ¹⁴C record for the complete brackish Littorina Stage of the Baltic Sea, i.e. the last 8000 years. In addition, the project will apply the common cosmogenic radionuclide production rate variations to synchronize the new ¹⁰Be record to existing cosmogenic radionuclide time-series from sediment and ice core archives in the Circum-Baltic region and across the Northern Hemisphere.