Auxiliary Material for paper ‘Surface changes in the Eastern Labrador Sea around the onset of the Little Ice Age’ 

Paola Moffa-Sánchez
School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3YE. U.K.

Ian R. Hall 
School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3YE. U.K.

Stephen Barker
School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3YE. U.K.

David J.R. Thornalley
School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3YE. U.K. Now at Department of Geography, University College London, Pearson Building, Gower Street, London, WC1E 6BT. UK.

Igor Yashayaev
Ocean Circulation Section, Ocean Sciences Division, Bedford Institute of Oceanography, Fisheries and Oceans Canada, 1 Challenger Drive, P.O. Box 1006, Dartmouth, NS, B2Y 4A2, Canada.
Paleoceanography

Introduction:
In Supplementary Figure S1 we present measured temperature and salinity data over the last 70 years from the top 30 m from the Labrador Sea (Section AR7). This data reveal a positive correlation between temperature and salinity at the site on decadal time-scales with a correlation coeffient of 0.64 (Figure S1(a) and (b)). We calculate the predicted ?18O of the calcite (?18Opredicted) using the hydrographic temperature and salinity values and the Kim and O’Neil [1997] paleotemperature equation and the Labrador Sea ?18O-Salinity relationship from LeGrande and Schmidt [2006] (Note that other ?18O-Salinity relationships including the one from the Arctic/Nordic Seas were also used in order to test if this made any difference). We observe a strong co-variability of the ?18Opredicted with temperature and salinity indicating that temperature dominates the ?18Opredicted signal in the top 30 m of the water column in the Labrador Sea (Figure S1(c)). For instance, heavier ?18Opredicted values generally correspond to periods of fresher and colder waters. Furthermore, calculations excluding salinity variability do not show a modification of the general multi-decadal trend of the ?18Opredicted (Figure S1(a)).

1. Figure S1.pdf: (a) Summer months hydrographic time-series of temperature (red) and salinity (blue) values from the Labrador Sea (Hydrographic Section AR7W- See Fig.1 of Yashayaev [2007]) between 0-30 m depth. The black line is the predicted ?18O of the foraminiferal calcite, calculated using the temperature and salinity hydrographic measurements and the Kim and O’Neil [1997] paleotemperature equation and the Labrador Sea ?18O-Salinity relationship from LeGrande and Schmidt [LeGrande and Schmidt, 2006]. The grey line in this same graph indicates the predicted ?18O assuming constant salinity. The grey shaded areas highlight the difference of including versus not salinity in the predicted ?18O signal. (b) Cross-plot of the hydrographic temperature and salinity data presented in graph (a), (c) Cross-plot highlighting the correlation between the temperature and predicted ?18O.