3856 R. Steinfeldt et al.: Anthropogenic carbon in the Atlantic Figure 11. Zonal mean sections of Cant concentration changes (1tCant) based on decadal data for the periods between 1990 and 2010. (a, c, e) Western basin, (b, d, f) eastern basin, (a, b) 1990–2000, (c, d) 2000–2010, (e, f) 2010–2020. Regions with differences smaller than the error range are stippled. Contour lines are shown as in Fig. 2. infer mean decadal increase rates from the Cant inventories in 1990, 2000, 2010 and 2020 based on all CFC/SF6 data (values in Table 3). The resulting increase is 1.74 % yr?1 for the decade of 1990–2000, 1.73 % yr?1 for 2000–2010 and 1.68 % yr?1 for the last period of 2010–2020. All values are quite close to the result of 1.69 % yr?1 in Steinfeldt et al. (2009). Gruber et al. (2019) also inferred an expected Cant change based on the atmospheric CO2 increase and mean changes in the buffer factor and Cant disequilibrium. The re- sulting Cant change between 1994 and 2007 was 28 %, or 1.92 % yr?1. The higher value is probably because Gruber et al. (2019) considered only the atmospheric CO2 increase between 1994 and 2007, which is larger than a longer-term mean, as the CO2 growth rate has increased. However, the Cant increase in the older waters in the ocean interior reflects the smaller rise in atmospheric CO2 from earlier decades. 3.3.2 Deviations of Cant storage from a steady state Here, we come back to the Cant accumulation anomalies 1tCanomant that have been introduced in Sect. 2.3. The magni- tude of these anomalies over the decades 1990–2000, 2000– 2010 and 2010–2020 is presented in Table 6. It can also be in- ferred from Fig. 9 as the difference between the boxes and the horizontal colored lines, which show the Cant increase based Biogeosciences, 21, 3839–3867, 2024 https://doi.org/10.5194/bg-21-3839-2024