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Holocene North Atlantic Overturning in an atmosphere-ocean-sea ice model compared to proxy-based reconstructions

Blaschek, M; Renssen, H; Kissel, C; Thornalley, D; (2015) Holocene North Atlantic Overturning in an atmosphere-ocean-sea ice model compared to proxy-based reconstructions. Paleoceanography , 30 (11) pp. 1503-1524. 10.1002/2015PA002828. Green open access

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Abstract

Climate and ocean circulation in the North Atlantic region changed over the course of the Holocene, partly because of disintegrating ice sheets and partly because of an orbital-induced insolation trend. In the Nordic Seas, this impact was accompanied by a rather small, but significant, amount of Greenland ice sheet melting. We have employed the EMIC LOVECLIM and compared our model simulations with proxy-based reconstructions of δ13C, sortable silt, and magnetic susceptibility (κ) used to infer changes in past ocean circulation over the last 9000 years. The various reconstructions exhibit different long-term evolutions suggesting changes in either the overturning of the Atlantic in total or of subcomponents of the ocean circulation, such as the overflow waters across the Greenland-Scotland ridge. Thus, the question arises whether these reconstructions are consistent with each other or not. A comparison with model results indicates that δ13C, employed as an indicator of overturning, agrees well with the long-term evolution of the modeled Atlantic meridional overturning circulation (AMOC). The model results suggest that different long-term trends in subcomponents of the AMOC, such as Iceland-Scotland overflow water, are consistent with proxy-based reconstructions and allow some of the reconstructions to be reconciled with the modeled and reconstructed (from δ13C) AMOC evolution. We find a weak early Holocene AMOC, which recovers by 7 kyr B.P. and shows a weak increasing trend of 88 ± 1 mSv/kyr toward present, with relatively low variability on centennial to millennial timescales.

Type: Article
Title: Holocene North Atlantic Overturning in an atmosphere-ocean-sea ice model compared to proxy-based reconstructions
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/2015PA002828
Publisher version: http://doi.org/10.1002/2015PA002828
Language: English
Additional information: © 2015. American Geophysical Union. All Rights Reserved.
Keywords: Science & Technology, Physical Sciences, Life Sciences & Biomedicine, Geosciences, Multidisciplinary, Oceanography, Paleontology, Geology, DEEP-WATER, THERMAL MAXIMUM, NORDIC SEAS, LAST DEGLACIATION, BOTTOM-WATER, CARBON-CYCLE, CLIMATE, CIRCULATION, STRENGTH, FLOW
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/1499091
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