Postglacial paleoceanography of the western Barents Sea: Implications for alkenone-based sea surface temperatures and primary productivity

Type Article
Date 2019-11
Language English
Author(s) Łącka Magdalena1, Cao Min2, 3, Rosell-Melé Antoni3, 4, Pawłowska Joanna1, Kucharska Małgorzata1, Forwick Matthias5, Zajączkowski Marek1
Affiliation(s) 1 : Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81-712, Sopot, Poland
2 : Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing, 400715, China
3 : Institute of Environmental Science and Technology (ICTA-UAB), Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
4 : Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
5 : Department of Geosciences, UiT The Arctic University of Norway in Tromsø, N-9037, Tromsø, Norway
Source Quaternary Science Reviews (0277-3791) (Elsevier BV), 2019-11 , Vol. 224 , P. 105973 (14p.)
DOI 10.1016/j.quascirev.2019.105973
WOS© Times Cited 7
Keyword(s) Alkenones, Stratification, Holocene, Sea ice decrease, Global warming, North Atlantic Current, Arctic
Abstract

The increasing influence of Atlantic Water (AW) in the Barents Sea, a process known as “Atlantification”, is gradually decreasing sea ice cover in the region. Ongoing global climate warming is likely to be one of its drivers, but to further understand the role of natural variability and the biogeochemical impacts of the inflow of AW into the western Barents Sea, we reconstructed sea surface temperatures (SSTs) and primary productivity in Storfjordrenna, a climatically sensitive area south of Spitsbergen, between approximately 13,950 cal yr BP and 1300 cal yr BP. The alkenone proxy has been applied to reconstruct SSTs, and the alkenone accumulation rate in marine sediments has been used to infer changes in primary productivity. Our data show that the SST increase was concomitant with the progressive loss of sea ice cover and an increase in primary productivity in the western Barents Sea. We interpret these changes as reflecting the increasing influence of AW in the area as the ice sheets retreated in Svalbard. The transition from the Arctic to the Atlantic domain first occurred after 11,500 cal yr BP, as the Arctic Front moved eastward of the study site but with considerable variability in surface ocean conditions. High SSTs at approximately 6400 cal yr BP may have led to limited winter surface cooling, likely inhibiting convective mixing and the return of nutrients to the euphotic zone and/or enhanced organic matter consumption by zooplankton due to an earlier light signal in the ice-free Storfjordrenna. During the late Holocene (3600-1300 cal yr BP), low insolation facilitated sea ice formation and thus brine production. The former may have launched convective water mixing and increased nutrient resupply to the sea surface, consequently enhancing primary productivity in Storfjordrenna. We propose that, on the basis of the paleoceanographic evidence, the modern increasing inflow of warm AW and the disappearance of pack ice on the Eurasian continental shelf are likely to weaken convective water mixing and decrease primary production in the region.

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Łącka Magdalena, Cao Min, Rosell-Melé Antoni, Pawłowska Joanna, Kucharska Małgorzata, Forwick Matthias, Zajączkowski Marek (2019). Postglacial paleoceanography of the western Barents Sea: Implications for alkenone-based sea surface temperatures and primary productivity. Quaternary Science Reviews, 224, 105973 (14p.). Publisher's official version : https://doi.org/10.1016/j.quascirev.2019.105973 , Open Access version : https://archimer.ifremer.fr/doc/00585/69740/