IP25 and Uk'37 proxy records from sediment cores from the subarctic Pacific and the Bering Sea, supplement to: Méheust, Marie; Stein, Ruediger; Fahl, Kirsten; Gersonde, Rainer (2018): Sea-ice variability in the subarctic North Pacific and adjacent Bering Sea during the past 25 ka: new insights from IP25 and Uk′37 proxy records. In: O'Cofaigh, C., Kirchner, N., Federov, G., Noormets, R. and de Vernal, A. (Eds.), Arctic environmental change beyond instrumental records, Special PAST Gateways issue of arktos, arktos - The Journal of Arctic Geosciences, 4(1)

• Main Authors: Méheust, Marie, Stein, Ruediger, Fahl, Kirsten, Gersonde, Rainer
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2018
• Subjects: Paleoenvironmental Reconstructions from Marine Sediments @ AWI AWI_Paleo; Arctic; Bering Sea; Pacific; Phytoplankton; Sea ice; Subarctic
• Online Access: https://dx.doi.org/10.1594/pangaea.887833; https://doi.pangaea.de/10.1594/PANGAEA.887833

This study focusses on the last glacial-deglacial-Holocene spatial and temporal variability in sea-ice cover based on organic geochemical analyses of marine sediment cores from the subarctic Pacific and the Bering Sea. By means of the sea ice proxy "IP25/PIP25" and phytoplankton-derived biomarkers (specific sterols and alkenones), we reconstruct the spring sea-ice conditions, (summer) sea-surface temperature (SST) and primary productivity, respectively. The large variability of sea ice was explained by a combination of local and global factors, such as solar insolation, global climate anomalies and sea-level changes controlling the oceanographic circulation and water mass exchange between the subarctic Pacific and the Bering Sea. During the Last Glacial Maximum, extensive sea-ice cover prevailed over large part of the subarctic Pacific and the Bering Sea. The following deglaciation is characterized by a rapid sea-ice advance and retreat. During cold periods (Heinrich Stadial 1 and Younger Dryas) seasonal sea-ice cover generally coincided with low alkenone SSTs and low primary productivity. Conversely, during warmer intervals (Bølling/Allerød, Early Holocene) reduced sea ice or ice-free conditions prevailed in the study area. In the northern Bering Sea continental shelf a late-Early/Mid Holocene shift to marginal sea-ice conditions is in line with the simultaneous wide-spread sea-ice recovery observed in the other Arctic marginal seas and is likely initiated by the lower Northern Hemisphere insolation and surface-water cooling.