Storminess reconstruction in the northeastern Baltic Sea region over the past 7600 years based on aeolian sand influx into coastal bogs

Abstract

This study aims to reconstruct the changes in storminess during the past 7600 years in the northeastern Baltic Sea region. For storminess reconstructions, aeolian sand influx (ASI) in coastal peat bog deposits was applied as an indicator of the past storminess. We analyzed cores from four peat bogs in the western and northern coastal areas of Estonia: the cores from Hiiumaa N, Hiiumaa SW, Saaremaa and Juminda study sites covered the past 3700, 3750, 2400, and 8400 years, respectively. The sediment chronologies were established using 36 14C dates. Image-analysis method ( ImageJ) was used to count and measure the grain size of all sand particles at every centimeter to gain high-resolution ASI records. Although minor site-to-site variations exist, all four ASI records were in general consistent, suggesting that stormier periods occurred around 7300, 6600, 5900, 4600, 3600, 2900, 2400, 2100, and 1600 cal yr BP and over the last 1200 years. The results and comparisons with other storminess and climate studies indicate a shift in climatic conditions around 2500 cal yr BP when stormy periods became more frequent. The ASI values were also high during the last millennium, suggesting either higher storminess or more suitable transport mechanisms for sand into the coastal bogs: the niveo-aeolian transport mode could have been favored in winters, especially during the Little Ice Age, and human impact on landscapes has probably increased over the past centuries.