Sea-ice dynamics in an Arctic coastal polynya during the past 6500 years
- 419 Downloads
The production of high-salinity brines during sea-ice freezing in circum-arctic coastal polynyas is thought to be part of northern deep water formation as it supplies additional dense waters to the Atlantic meridional overturning circulation system. To better predict the effect of possible future summer ice-free conditions in the Arctic Ocean on global climate, it is important to improve our understanding of how climate change has affected sea-ice and brine formation, and thus finally dense water formation during the past. Here, we show temporal coherence between sea-ice conditions in a key Arctic polynya (Storfjorden, Svalbard) and patterns of deep water convection in the neighbouring Nordic Seas over the last 6500 years. A period of frequent sea-ice melting and freezing between 6.5 and 2.8 ka BP coincided with enhanced deep water renewal in the Nordic Seas. Near-permanent sea-ice cover and low brine rejection after 2.8 ka BP likely reduced the overflow of high-salinity shelf waters, concomitant with a gradual slow down of deep water convection in the Nordic Seas, which occurred along with a regional expansion in sea-ice and surface water freshening. The Storfjorden polynya sea-ice factory restarted at ~0.5 ka BP, coincident with renewed deep water penetration to the Arctic and climate amelioration over Svalbard. The identified synergy between Arctic polynya sea-ice conditions and deep water convection during the present interglacial is an indication of the potential consequences for ocean ventilation during states with permanent sea-ice cover or future Arctic ice-free conditions.
KeywordsArctic Storfjorden Polynya Holocene Sea ice
This work is a contribution to the CASE Initial Training Network funded by the European Community’s 7th Framework Programme FP7 2007/2013, Marie-Curie Actions, under Grant Agreement No. 238111. The research is part of the Centre for Arctic Gas Hydrate, Environment and Climate and was supported by the Research Council of Norway through its Centres of Excellence funding scheme Grant No. 223259. We thank the reviewers for their help improving the manuscript significantly.
- 7.Belt ST, Cabedo-Sanz P, Smik L, Navarro-Rodriguez A, Berben SMP, Knies J, Husum K (2015) Identification of paleo Arctic winter sea ice limits and the marginal ice zone: optimised biomarker-based reconstructions of late Quaternary Arctic sea ice. Earth Planet Sci Lett 431:127–139. doi: 10.1016/j.epsl.2015.09.020 CrossRefGoogle Scholar
- 10.Broecker WS, Peng T-H (1982) Tracers in the sea. Lamont-Doherty Geological Observatory Columbia University, New YorkGoogle Scholar
- 18.Funder S et al. (2011) A 10,000-year record of arctic ocean sea-ice variability-view from the beach. Science 333:747–750. doi: 10.1126/science.1202760
- 22.Jensen H (2000) Resultater av kjemiske analyser av prøver av Svalbard kull og tilgrensende bergarter over, under og mellom kull fløtsene. NGU, TrondheimGoogle Scholar
- 23.Jochum KP, Willbold M, Raczek I, Stoll B, Herwig K (2005) Chemical characterization of the USGS reference glasses GSA-1G, GSC-1G, GSD-1G, GSE-1G, BCR-2G, BHVO-2G and BIR-1G using EPMA, ID-TIMS, ID-ICP-MS and LA-ICP-MS. Geostand Geoanalytical Res 29(3):285–302. doi: 10.1111/j.1751-908X.2005.tb00901.x CrossRefGoogle Scholar
- 32.Ottesen RT et al (2010) Geochemical atlas of Norway, Part 2: Geochemical atlas of Spitsbergen. Chemical composition of overbank sediments. Norges geologiske undersøkelse/Norges vassdrags- og energidirektorat, TrondheimGoogle Scholar
- 42.Sarnthein M, Van Kreveld S, Erlenkeuser H, Grootes PM, Kucera M, Pflaumann U, Schulz M (2003) Centennial-to-millennial-scale periodicities of Holocene climate and sediment injections off the western Barents shelf, 75 degrees N. Boreas 32:447–461. doi: 10.1080/03009480310003351 CrossRefGoogle Scholar
- 44.Semenov VA, Park W, Latif M (2009) Barents Sea inflow shutdown: a new mechanism for rapid climate changes. Geophys Res Lett. doi:1029/2009gl038911Google Scholar
- 54.Wedepohl KJ (1991) The composition of the upper earth’s crust and the natural cycles of selected metals. Metals in natural raw materials. Natural resources. In: Merian E (ed) Metals and their compounds in the environment. VCH, Weinheim, pp 3–17Google Scholar