Seasonal climate variations in the Baltic Sea during the Last Interglacial based on foraminiferal geochemistry. (15th November 2021)

• Record Type: Journal Article
• Authors: Ni, S.; Quintana Krupinski, N.B.; Chonewicz, J.; Groeneveld, J.; Knudsen, K.L.; Seidenkrantz, M.-S.; Filipsson, H.L.
• Is Part Of: Quaternary science reviews. Volume 272(2021)
• Publication Date: 2021-11-15
• Subjects: The Last Interglacial -- Seasonality -- Hydrography -- Benthic foraminifera -- The Baltic Sea -- The Skagerrak; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2021.107220
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: Climate during the Last Interglacial period (LIG, Marine Isotope Stage 5e) was on average warmer than the present, with a higher global sea level but also more unstable conditions. Today, the Baltic Sea interacts strongly with conditions in the North Atlantic region, and this interaction was likely even stronger during the LIG. We here present a reconstruction of seawater conditions during the LIG based on benthic foraminiferal geochemistry (stable isotopes and trace elements) and compare these records with modern marine monitoring data to evaluate seasonal hydrographic conditions in the western and southern Baltic Sea during the first half of the LIG (130–123 ka BP). Our reconstructions reflect the evolution of seasonal temperature and salinity, rather than annual mean conditions. The spring LIG bottom water temperatures in the Skagerrak and Kattegat were ∼2–3 °C higher compared to the modern spring bottom water temperatures. During the LIG, there was an increase in seasonality in bottom water temperature (progressively warmer summers and cooler springs) in the southern Baltic Sea, which can be linked to seasonal insolation changes. Moreover, our data suggest a decreased gradient of bottom water salinity along a transect through the Skagerrak-Kattegat-Danish Straits-southern Baltic Sea, supporting previous investigations inferring a stronger ocean-water influx into the Baltic Sea during the LIG than at present. Highlights: Seasonal hydrographic changes of the bottom water during the Last Interglacial as recorded by foraminiferal geochemistry. The seasonality of bottom water temperatures in the Baltic Sea increased during the first half of the Last Interglacial. Increased seasonality can be ascribed to the increase in summer insolation and potentially to the reduced spring insolation.