Fig. 4: Summary of deep-ocean temperature and δ18Osw changes in the North Atlantic between the LGM and the modern ocean.
From: Relatively warm deep-water formation persisted in the Last Glacial Maximum
a,b, Calculated difference in deep-ocean temperatures (ΔT; a) and δ18Osw-ivc (Δδ18Osw-ivc; b) derived from benthic foraminiferal Mg/Ca- and Δ47-based estimates (dark blue and green, respectively) and published sedimentary pore-water δ18O-based estimates (light blue6; Methods; potential temperature was converted to in situ temperature using the Gibbs seawater Oceanographic Toolbox (TEOS-10 standard48); δ18Osw is reported relative to the SMOW scale). For the Northwest Atlantic, we exclude data from the subtropically influenced site ODP-172-1055 and the abyssal site KNR-197-10-17GGC. Glacial Northeast Atlantic data are from sediment cores RAPiD-10-1P, RAPiD-17-5P and BOFS17K (Extended Data Table 1). Associated errors bars are ±2 s.e. (Methods). Modern temperature data were taken from WOA23 (ref. 7) (grey), and in the absence of equivalent δ18Osw, we assume a modern δ18Osw of 0.20 ± 0.2‰ and 0.25 ± 0.05‰ for the Northwest and Northeast Atlantic, respectively (for example, ref. 47). As in Fig. 3, glacial δ18Osw has been corrected by −1.0‰ to account for changes in global ice volume (Methods). We also calculated ΔT and Δδ18Osw-ivc for the LGM and mid-to-late Holocene using paired samples where available; the resulting estimates show close agreement with our broader climatological comparison (ΔTMg/Ca = −1.7 ± 0.7 °C, Δδ18Osw-ivc(Mg/Ca) = 0.5 ± 0.2‰, n = 5; ΔT(Δ47) = −2.2 ± 2.0 °C, Δδ18Osw-ivc(Δ47) = 0.4 ± 0.5‰, n = 3; Methods and Source Data).
