The Atlantic Meridional Overturning Circulation (AMOC), a tipping component of the climate system, is projected to slowdown during the 21st century in response to increased atmospheric CO₂ concentration. The rate and start of the weakening are associated with relatively large uncertainties. Observed sea surface temperature-based reconstructions indicate that AMOC has been weakening since the mid-20th century, but its forcing factors are not fully understood. Here we provide dynamical observational evidence that the increasing atmospheric CO₂ concentration affects the North Atlantic heat fluxes and precipitation rate, and weakens AMOC, consistent with numerical simulations. The inferred weakening, starting in the late 19th century, earlier than previously suggested, is estimated at 3.7 ± 1.0 Sv over the 1854–2016 period, which is larger than it is shown in numerical simulations (1.4 ± 1.4 Sv).

作为气候系统的重要组成部分，大西洋经向翻转循环（AMOC）预计将在21世纪随着大气CO ₂浓度增加而放缓。减弱的速度和开始与相对较大的不确定性有关。观察到的基于海面温度的重建表明，自20世纪中叶以来AMOC一直在减弱，但是其强迫因素尚未得到充分了解。在这里，我们提供了动态的观测证据，表明大气中的CO ₂不断增加浓度影响北大西洋的热通量和降水速率，并削弱AMOC，这与数值模拟一致。推断的减弱始于19世纪末，早于先前的建议，在1854–2016年期间估计为3.7±1.0 Sv，大于数值模拟中显示的数值（1.4±1.4 Sv）。