Seasonal sea ice cover during the warm Pliocene: Evidence from the Iceland Sea (ODP Site 907)

• Published in: Earth and planetary science letters Vol. 481; pp. 61 - 72
• Main Authors: Clotten, Caroline, Stein, Ruediger, Fahl, Kirsten, De Schepper, Stijn
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2018
• Subjects: alkenones; East Greenland Current; IP25; Pliocene; sea ice; sterols; IP25; sterols; East Greenland Current; alkenones; Pliocene; sea ice
• ISSN: 0012-821X; 1385-013X
• DOI: 10.1016/j.epsl.2017.10.011

Sea ice is a critical component in the Arctic and global climate system, yet little is known about its extent and variability during past warm intervals, such as the Pliocene (5.33–2.58 Ma). Here, we present the first multi-proxy (IP25, sterols, alkenones, palynology) sea ice reconstructions for the Late Pliocene Iceland Sea (ODP Site 907). Our interpretation of a seasonal sea ice cover with occasional ice-free intervals between 3.50–3.00 Ma is supported by reconstructed alkenone-based summer sea surface temperatures. As evidenced from brassicasterol and dinosterol, primary productivity was low between 3.50 and 3.00 Ma and the site experienced generally oligotrophic conditions. The East Greenland Current (and East Icelandic Current) may have transported sea ice into the Iceland Sea and/or brought cooler and fresher waters favoring local sea ice formation. Between 3.00 and 2.40 Ma, the Iceland Sea is mainly sea ice-free, but seasonal sea ice occurred between 2.81 and 2.74 Ma. Sea ice extending into the Iceland Sea at this time may have acted as a positive feedback for the build-up of the Greenland Ice Sheet (GIS), which underwent a major expansion ∼2.75 Ma. Thereafter, most likely a stable sea ice edge developed close to Greenland, possibly changing together with the expansion and retreat of the GIS and affecting the productivity in the Iceland Sea. •First multi-proxy reconstruction of sea ice in the Pliocene Iceland Sea.•Seasonal sea ice occurred in the Iceland Sea during Late Pliocene (3.5–3.0 Ma).•A sea ice edge likely shifts with Greenland Ice Sheet waxing/waning after 2.75 Ma.