Late Holocene shift towards enhanced oceanic variability in a high-Arctic Svalbard fjord (79°N) at 2500 cal. yr BP

Paleoclimate records are crucial for understanding current changes taking place in the Arctic, e.g., the amplified warming and associated changes in sea-ice cover. However, paleoclimate and -oceanographic reconstructions, especially from the high Arctic, are scarce. Here, we present a reconstruction of sea surface and paleoenvironmental conditions from a Holocene marine sediment core collected from a high-Arctic fjord, Isvika Bay, Nordauslandet, Svalbard (79°N). Our proxies include qualitative diatom assemblage data [focusing on the Marginal Ice Zone (MIZ) taxa], a quantitative diatom-based August sea surface temperature (aSST) reconstruction, sediment grain-size distribution, and ice-rafted debris (IRD) spanning the period from 4200 cal. yr BP to the Little Ice Age (LIA) at ca. 200 cal. yr BP. The results reveal cold and stable, glacier-proximal conditions for the beginning of the late Holocene (from 4200 to 2500 cal. yr BP). Then, at 2500 cal. yr BP, the environment shifted into distinctly more fluctuating conditions, where colder and warmer aSSTs alternated in a glacier-distal environment. During the latter part of the late Holocene, sea-ice cover was extensive, yet variable, negatively co-varying with aSST. Based on our diatom data, we observe a clear increase in the influence of Atlantic water in Isvika Bay during the last ca. 600 years.