3852 R. Steinfeldt et al.: Anthropogenic carbon in the Atlantic Figure 8. Zonal mean sections of Cant referenced to 1994 from (a–b) the1C? method (Sabine et al., 2004), (c–d) the GF method (Khatiwala et al., 2013) and (e–f) our TTD method. Contour lines are shown as in Fig. 2. and eastern basins are depicted. The Cant increases shown in Figs. 10 and 11 reveal similar patterns to the Cant distri- bution in Figs. 6 and 7; i.e., the Cant increase over time is high when the Cant concentration is also high. The largest increase appears close to the surface and in the subtropical mode waters, and the NADW also contributes significantly to the Atlantic Cant storage. This becomes particularly evi- dent when comparing the Cant increase for the whole water column (Fig. 10a, c and e) with that for the deep and bot- tom waters only (Fig. 10b, d and f): in the subpolar North Atlantic, where the deep water layer extends close to the sur- face, the Cant storage in deep and bottom waters alone is al- most as large as for the total water column. The southward propagation of NADW in the western basin is reflected by a significant Cant increase that extends to 10° S and is most pronounced in the LSW layer (Fig. 11a, c and e). In the east- ern basin, any noticeable spatial Cant increase in the younger NADW layer (LSW and ISOW) is limited to the region north of 30° N. The deep and bottom waters in the Atlantic that are not in- fluenced by younger NADW mainly show insignificant Cant changes. South of about 40°S, the AABW exhibits a Cant Biogeosciences, 21, 3839–3867, 2024 https://doi.org/10.5194/bg-21-3839-2024