Atlantification at the Arctic Gateway: Past and Present Dynamics

Reconstructing climate patterns from the Common Era is necessary for placing modern human-driven climate changes within the context of natural climatic variations. This is particularly relevant for the Arctic, which is warming faster than any other. This global trend is tied to rapid sea ice loss and the increasing influx of Atlantic waters into the Arctic basin, a phenomenon called "Atlantification". In this context, we reconstruct the last centuries paleoenvironmental changes in the Arctic region from sediment cores strategically located along the Barents Sea (HH1141, 74.015°N 21.071°E, -285 m; HH1181, 74.081°N 21.362°E, -298 m water depth; HH969, 76.765°N 35.831°E, -174 m water depth), and on the northern margin of the Svalbard Archipelago (KH21-234-04 (80.3531ºN 16.308ºE, -394 m water depth), based on geochronological and geochemical analyses, benthic foraminiferal data and organic biomarkers. The Age-depth are based on excess ²¹⁰Pb, and are extrapolated down-core, assuming stable sediment accumulation rates (SAR) before the 20th century. The results allow us to identify two main oceanographic intervals. Pre-1900 ys CE, the dominance of Elphidium clavatum, Cassidulina reniforme, Islandiella helenae, Islandiella norcrossi, Stainforthia feylingi, Stainforthia loeblechi, together with a high concentration of biomarker (spring sea ice biomarker IP₂₅, and alkenones), indicate cold conditions. The second interval, corresponding to the 20th century, is characterized by the presence of Adercotryma glomeratum, Trifarina angulosa, Nonionellina labradorica, Globobulimina auriculata, Melonis barleanus, Buccella frigida, documenting warm water mass inflow related to the expand incursion of Atlantic waters. Moreover, biomarker analyses provide further details of the paleoceanographic conditions showing less seasonal sea ice influence in the region and the intrusion of Atlantic waters within the Arctic domain. This work sets another milestone in our understanding of the “Atlantification” process that is crucial to forecasting the environmental changes in this region that are susceptible to heat transport through the Atlantic gateways, which affects climate and ecosystems.