Figure 4

Mean water mass _xc[CO₃²⁻] (μmol kg⁻¹) versus atmospheric CO₂ concentration (ppm) in the Northeast Atlantic: NACW (cyan), MW (orange), LSW (purple) and upper and lower NADW (pink and light green). Only linear trends (μmol kg⁻¹ ppm⁻¹) with a statistical p-value < 0.001 have been depicted (Supplementary Information Table S1), and the grey shading accounts for the trend errors. Uncertainties in the mean properties are two times the standard error of the mean (i.e., 95% confidence interval). The year of the cruise is represented in the upper x-axis. The light red zone below the limit of 0 _xc[CO₃²⁻] represents undersaturated waters with respect to aragonite.