Holocene relative water level and storminess variation recorded in the coastal peat bogs of the Vistula Lagoon, southern Baltic Sea

The history of regional sea-level changes is critically important for building global environmental reconstruction models and identifying major driving forces. The coastal peatlands located on the terraces of the Vistula Lagoon (Gulf of Gda.nsk, southern Baltic Sea) are one of the most valuable, and not yet fully explored, archives of the regional history of sea- level and storminess changes during the middle and late Holocene. The comprehensive analysis of peat and gyttja allowed establishing radiocarbon calibrated time series of stable carbon isotope composition (delta C-13), pollen and diatom data. The results indicate that the sea-level increased from similar to 20 to 8 m below present sea level between 9000 and 7000 yr b2k at an average rate of similar to 6 mm/year. Around 5000 yr b2k, the sea-level was similar to 2.5 m lower than at present, which indicates a decrease in the rate of sea-level rise to similar to 2.75 mm/year between 7000 and 5000 yr b2k. During the last 5000 years, the sea-level had risen at similar to 0.5 mm/year to the present position. Changes in brackish diatoms, Pediastrum sp. concentrations, and maxima of delta C-13 suggest ten periods of increased rates of sealevel rise and storminess between 7000 and 1500 yr b2k. Increased sea-levels and stormy surges on the peat surface occurred mainly during cold periods or the periods of transitions. These observations are in good agreement with climate fluctuations in the Northern Hemisphere related to the variations in total regional solar irradiation. (C) 2022 The Authors. Published by Elsevier Ltd.

Automated summary

The study of the coastal peatlands in the Vistula Lagoon provides valuable insights into the regional sea-level and storminess changes during the middle and late Holocene. The analysis of peat and gyttja revealed the sea-level rise from 20 to 8 meters below present sea level between 9000 and 7000 years ago at an average rate of 6 mm/year. The rate of sea-level rise decreased to 2.75 mm/year between 7000 and 5000 years ago, with the sea-level being 2.5 meters lower than present around 5000 years ago. In the last 5000 years, the sea-level has risen at a rate of 0.5 mm/year to its current position. The study also identified ten periods of increased sea-level rise and storminess between 7000 and 1500 years ago, which were mainly associated with cold periods or transitions and linked to variations in regional solar irradiation.