Extended Data Figure 6. Magnesium/calcium ratios of benthic foraminifer shells in Pine Island Bay.

The magnesium/calcium (Mg/Ca) ratios, which were measured on shells of the benthic foraminifer species A. angulosa from core PS75/160, are shown with an adjustment for a potential diagenetic Mg contribution by assuming a magnesium/manganese (Mg/Mn) ratio of 0.15±0.05 mol mol^-1 in the diagenetic coating (a), and with an adjustment for a potential diagenetic Mg contribution by assuming a range of Mg/Mn ratios in the diagenetic coating (b). The Mg/Ca ratios in b are displayed as averages of samples taken from the time intervals 10.0-7.5 kyr BP (4 samples), 7.5-4.0 kyr BP (2 samples) and 4.0-0 kyr BP (4 samples), both without adjustment and with adjustment for potential diagenetic Mg contributions assuming Mg/Mn ratios in diagenetic coatings of 0.10, 0.15, 0.20 and 0.25 mol mol^-1 (references ^68–72). Error bars in a highlight the uncertainty of ±0.05 mol mol^-1 for the Mg/Mn composition of the coating and the 2 s.d. range of the ages of the Mg/Ca samples, which were calculated from the calibrated AMS ¹⁴C dates obtained from neighbouring sample horizons (Extended Data Table 1).