Fig. 2

Synchronized Antarctic and North Atlantic climate records on the IntCal13 timescale. a CO₂ concentration from WAIS Divide ice cores (WDC)³. b δ¹⁸O values from NGRIP ice cores¹⁰¹. c Bottom and surface ¹⁴C ventilation (R) histories from core MD99-2284 based on benthic and planktic foraminifera, respectively. Dots indicate individual measurements together with their 2σ error bars. Shading reflects the 95% posterior credible interval (2σ) of ¹⁴C ventilation as a function of age found by MCMC using random walk model (Methods) and taking into account both the analytical and chronological uncertainty in our observed data. Orange dot reflects individual early GS-1 measurement from nearby core JM11-FI-19PC (1179 m)¹² (not incorporated in the random walk model). Red and blue arrows indicate the modern surface (0–100 m) and bottom (1200–1500 m) R values at the study site¹⁰⁴, respectively. Grey arrow indicates modern mean marine R. d Benthic-planktic (B-P) offset based on ventilation estimates in (c) and reflecting the strength of deep convection and NADW formation in the Nordic Seas. Red line and shading denote the posterior median value and pointwise 95% credible intervals. Purple square indicates a B-P estimate from the Vøring Plateau (1048 m) based on one solitary U/Th dated deep-sea coral¹⁰⁵ (average of three B-Atm measurements—Supplementary Fig. 9) and presented on its independent time scale. e Second principal component of all foraminifera counts in core MD99-2284 dominated by N. labradoricum, which is an indicator for the proximity of the Polar Front and sea-ice edge¹⁰⁶ (Supplementary Fig. 10). f Coarse-grained (>150 μm) ice-rafted debris count and PIP₂₅ index in core MD99-2284 reflecting iceberg rafting and occurrence of spring sea-ice cover, respectively. g Abundance of long-chain n-alkanes in core MD99-2284 derived from terrestrial higher plants¹⁰⁷ and indicating meltwater discharge. All records are presented on the IntCal13 timescale¹⁴. Greenland stratigraphic events relative to the IntCal13 timescale are displayed at the top and cold events are highlighted with grey bars (GS: Greenland Stadial; GI: Greenland Interstadial; YD: Younger Dryas Stadial; BA: Bølling-Allerød Interstadial; HS1: Heinrich Stadial 1). Dashed vertical lines show tephra horizons identified in core MD99-2284