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Helena Filipsson, foto Erik Thor

Helena Filipsson

Professor

Helena Filipsson, foto Erik Thor

Last interglacial seasonal hydroclimate in the North Sea–Baltic Sea region

Author

  • S. Ni
  • Z. Lu
  • Q. Zhang
  • J. Groeneveld
  • Karen Luise Knudsen
  • M. S. Seidenkrantz
  • H. L. Filipsson

Summary, in English

The Last Interglacial (LIG) experienced substantial changes in seasonal insolation compared with the present day, which may have affected the hydrography and water-mass exchange in the North Sea and Baltic Sea region. Here we investigate the effects of solar radiation and greenhouse gas (GHG) forcing on the regional climate by analyzing model simulations of the LIG (127 ka BP), pre-industrial (PI, 1850 CE), and present-day (PD, 1990 CE) climates. We also interpret the reconstructed seasonal bottom water conditions using benthic foraminifera and geochemistry data. Our simulations reveal that during the LIG, the Baltic Sea region (including the Kattegat and the Danish Straits) experienced more saline and colder bottom waters than those in the PD, in agreement with the reconstruction data. This can be attributed to lower GHG levels and enhanced water exchange of cooler, saline North Sea water into the Baltic Sea during the LIG. The thermocline was stronger during the summer months in the LIG, mainly due to the higher sea surface temperature (SST) compared to that of the PD resulting from increased summer insolation. Further, the temperature anomalies (LIG–PD) show significant inverse correlations with the precipitation–minus–evaporation (P–E) at the Baltic Sea entrance. However, the P–E balance appears to have had minimal impact on salinity changes in the North Sea, the Baltic Proper, and the open sea area. Our findings indicate that monthly surface and bottom water salinity anomalies of LIG-PI exhibit strong positive correlations with the North Atlantic Oscillation (NAO) anomalies in the Baltic entrance region. During the LIG, a more positive phase of the NAO index in autumn played a crucial role in wind-driven major inflows and led to more intensive water exchange in the North Sea–Baltic Sea region compared to the late Holocene.

Department/s

  • Centre for Environmental and Climate Science (CEC)
  • MERGE: ModElling the Regional and Global Earth system
  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • Dept of Physical Geography and Ecosystem Science
  • Quaternary Sciences

Publishing year

2023-07-15

Language

English

Publication/Series

Quaternary Science Reviews

Volume

312

Document type

Journal article

Publisher

Elsevier

Topic

  • Climate Research
  • Oceanography, Hydrology, Water Resources

Keywords

  • Baltic Sea
  • Data-model comparison
  • EC-Earth model
  • Evaporation
  • Greenhouse Gas (GHG)
  • Hydrography
  • Insolation
  • North Atlantic Oscillation (NAO)
  • Paleoceanography
  • Precipitation
  • Salinity
  • Seasonality
  • Temperature
  • The Last Interglacial

Status

Published

Project

  • MERGE SP: Proxy-based reconstructions and model simulations of seasonal climate variations during the Last Interglacial in the Baltic Sea
  • Tracing hypoxia during warm periods in the Baltic Sea region - using synchrotron X-ray spectroscopy and plasma analytical methods

ISBN/ISSN/Other

  • ISSN: 0277-3791