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 Gdańsk, 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 (δ¹³C), pollen and diatom data. The results indicate that the sea-level increased from ∼20 to 8 m below present sea level between 9000 and 7000 yr b2k at an average rate of ∼6 mm/year. Around 5000 yr b2k, the sea-level was ∼2.5 m lower than at present, which indicates a decrease in the rate of sea-level rise to ∼2.75 mm/year between 7000 and 5000 yr b2k. During the last 5000 years, the sea-level had risen at ∼0.5 mm/year to the present position. Changes in brackish diatoms, Pediastrum sp. concentrations, and maxima of δ¹³C suggest ten periods of increased rates of sea-level 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.