Figure 3. North Atlantic proxy records which highlight millennial scale changes in ocean and atmospheric systems.

(a) Haematite stained grain (HSG) percentages from four stacked ocean cores³ indicating changes in North Atlantic ice rafted debris (IRD) and therefore ocean surface temperature, black vertical lines represent co-variation between this record and (b) the combined Cueva de Asiul speleothem δ¹⁸O record, with grey boundaries denoting the timing error based on the StalAge model, numbers identify Bond events, (c) changes in surface and subsurface density difference in the North Atlantic as a proxy for SPG strength and change in fresh water influx¹¹. Black lines indicate early Holocene connections between changing ocean circulation strengths and northern Iberian precipitation amount. Cross correlation analysis (see supplementary information) between the Asiul cave archive and the IRD data³ are (0–4000 BP, r² = 0.505, standard error = 0.125; 0–7800 BP r² = 0.165, standard error = 0.09; 9000–12,000 BP (t = −390) r² =  0.560, standard error = 0.106) and compared ocean density¹¹ data are (0–7800 BP r² = 0.34, standard error = 0.09).