Holocene oscillations in temperature and salinity of the surface subpolar North Atlantic

Thornalley, D. J. R. and Elderfield, H. and McCave, I. N. (2009) Holocene oscillations in temperature and salinity of the surface subpolar North Atlantic. Nature, 457 (7230). p. 711. ISSN 00280836 DOI 10.1038/nature07717

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Abstract

The Atlantic meridional overturning circulation (AMOC) transports warm salty surface waters to high latitudes, where they cool, sink and return southwards at depth. Through its attendant meridional heat transport, the AMOC helps maintain a warm northwestern European climate, and acts as a control on the global climate. Past climate fluctuations during the Holocene epoch (approx11,700 years ago to the present) have been linked with changes in North Atlantic Ocean circulation1, 2. The behaviour of the surface flowing salty water that helped drive overturning during past climatic changes is, however, not well known. Here we investigate the temperature and salinity changes of a substantial surface inflow to a region of deep-water formation throughout the Holocene. We find that the inflow has undergone millennial-scale variations in temperature and salinity (approx3.5 °C and approx1.5 practical salinity units, respectively) most probably controlled by subpolar gyre dynamics. The temperature and salinity variations correlate with previously reported periods of rapid climate change3. The inflow becomes more saline during enhanced freshwater flux to the subpolar North Atlantic. Model studies predict a weakening of AMOC in response to enhanced Arctic freshwater fluxes4, although the inflow can compensate on decadal timescales by becoming more saline5. Our data suggest that such a negative feedback mechanism may have operated during past intervals of climate change.

Item Type: Article
Uncontrolled Keywords: 08AREP; 2009 P; IA57;
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Nature
Volume: 457
Page Range: p. 711
Identification Number: 10.1038/nature07717
Depositing User: Sarah Humbert
Date Deposited: 17 Feb 2009 12:02
Last Modified: 23 Jul 2013 09:54
URI: http://eprints.esc.cam.ac.uk/id/eprint/847

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