The ocean absorbs approximately a quarter of the carbon dioxide currently released to the atmosphere by human activities (C_anth). A disproportionately large fraction accumulates in the North Atlantic due to the combined effects of transport by the Atlantic Meridional Overturning Circulation (AMOC) and air–sea exchange. However, discrepancies exist between modelled and observed estimates of the air–sea exchange due to unresolved ocean transport variability. Here we quantify the strength and variability of C_anth transports across 26.5° N in the North Atlantic between 2004 and 2012 using circulation measurements from the RAPID mooring array and hydrographic observations. Over this period, decreasing circulation strength tended to decrease northward C_anth transport, while increasing C_anth concentrations (preferentially in the upper limb of the overturning circulation) tended to increase northward C_anth transport. These two processes compensated each other over the 8.5-year period. While ocean transport and air–sea C_anth fluxes are approximately equal in magnitude, the increasing accumulation rate of C_anth in the North Atlantic combined with a stable ocean transport supply means we infer a growing contribution from air–sea C_anth fluxes over the period. North Atlantic C_anth accumulation is thus sensitive to AMOC strength, but growing atmospheric C_anth uptake continues to significantly impact C_anth transports.

海洋吸收了目前人类活动释放到大气中的二氧化碳的大约四分之一（C _anth）。由于大西洋经向翻转环流 (AMOC) 的运输和海气交换的综合影响，在北大西洋积累了不成比例的大部分。然而，由于未解决的海洋运输可变性，模拟和观测到的海气交换估计之间存在差异。在这里，我们使用来自 RAPID 系泊阵列和水文观测的环流测量来量化2004 年至 2012 年间北大西洋 26.5° N的 C _anth传输的强度和可变性。在此期间，环流强度的降低趋于向北降低 C _anth运输，而增加 C _anth浓度（优先在倾覆环流的上肢）倾向于增加向北的 C _anth运输。这两个过程在 8.5 年期间相互补偿。虽然海洋运输和海气-海C _anth通量在量级上大致相等，但北大西洋C _anth积累率的增加加上稳定的海洋运输供应意味着我们推断海气-海C _anth通量在此期间的贡献越来越大. 因此，北大西洋 C _anth积累对 AMOC 强度很敏感，但不断增长的大气 C _anth吸收继续显着影响 C_运输。