Learning from the past: Impact of the Arctic Oscillation on sea ice and marine productivity off northwest Greenland over the last 9,000 years

• Published in: Global Change Biology
• Main Authors: Limoges, Audrey, Weckström, Kaarina, Ribeiro, Sofia, Georgiadis, Eleanor, Hansen, Katrine Elnegaard, Martinez, Philippe, Seidenkrantz, Marit-Solveig, Giraudeau, Jacques, Crosta, Xavier, Massé, Guillaume
• Other Authors: Department of Earth Sciences, University of New Brunswick, University of New Brunswick (UNB), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Geological Survey of Denmark and Greenland (GEUS), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Department of Geoscience Aarhus, Aarhus University Aarhus, Takuvik International Research Laboratory, Université Laval Québec (ULaval)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: diatoms; highly branched isoprenoid (HBI) biomarkers; marine sediment; phytoplankton; paleoceanography; Arctic Oscillation; Baffin Bay; climate change; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDV.EE.BIO]Life Sciences [q-bio]/Ecology; environment/Bioclimatology; Arctic; Greenland; arctic cryosphere; Baffin; Climate change; Phytoplankton; Sea ice
• Online Access: https://hal.science/hal-02991688; https://hal.science/hal-02991688/document; https://hal.science/hal-02991688/file/Limogesetal2020_preprint.pdf; https://doi.org/10.1111/gcb.15334

International audience Climate warming is rapidly reshaping the Arctic cryosphere and ocean conditions, with consequences for sea ice and pelagic productivity patterns affecting the entire marine food web. To predict how ongoing changes will impact Arctic marine ecosystems, concerted effort from various disciplines is required. Here, we contribute multi-decadal reconstructions of changes in diatom production and sea-ice conditions in relation to Holocene climate and ocean conditions off Northwest Greenland. Our multiproxy study includes diatoms, sea-ice biomarkers (IP 25 and HBI III) and geochemical tracers (TOC, TOC:TN, δ 13 C, δ 15 N) from a sediment core record spanning the last ca. 9000 years. Our results suggest that the balance between the outflow of polar water from the Arctic, and input of Atlantic water from the Irminger Current into the West Greenland Current is a key factor in controlling sea-ice conditions, and both diatom phenology and production in northeastern Baffin Bay. Our proxy record notably shows that changes in sea-surface conditions initially forced by Neoglacial cooling were dynamically amplified by the shift in the dominant phase of the Arctic Oscillation (AO) mode that occurred at ca. 3000 yrs BP, and caused drastic changes in community composition and a decline in diatom production at the study site. In the future, with projected dominant positive AO conditions favored by Arctic warming, increased water column stratification may counteract the positive effect of a longer open-water growth season and negatively impact diatom production.