Environmental response to past and recent climate variability in the Trondheimsfjord region, central Norway - A multiproxy geochemical approach

Abstract

Norwegian fjords have a great potential for providing high-resolution sedimentary records that reflect local terrestrial and marine processes and therefore, fjords offer unique opportunities for the investigation of sedimentological and geochemical climatically induced processes. However, the complexity of fjord systems in terms of bathymetry and oceanography requires a profound knowledge of the fjord environmental setting before starting to interpret past climatic signals in Holocene sediment sequences. For this reason we first provide a comprehensive overview of the Trondheimsfjord environmental system by applying a multiproxy analysis on sixty surface sediments samples and compare our findings with available geochemical data from the fjords drainage area. Next we use the achieved knowledge to identify possible organic and inorganic geochemical climate proxies for changes in paleoproductivity and terrestrial run-off. Evidence for their consistency is provided by comparing a geochemical record of fifty years with instrumental data of temperature, precipitation, and river discharge in the Trondheimsfjord region as well as the NAO. Finally, a NAO reconstruction from past changes in paleoproductivity in the Trondheimsfjord is presented for the last 2,800 years.