The increase of atmospheric CO₂ (ref. ¹) has been predicted to impact the seasonal cycle of inorganic carbon in the global ocean^2,3, yet the observational evidence to verify this prediction has been missing. Here, using an observation-based product of the oceanic partial pressure of CO₂ (p_CO2) covering the past 34 years, we find that the winter-to-summer difference of the p_CO2 has increased on average by 2.2 ± 0.4 μatm per decade from 1982 to 2015 poleward of 10° latitude. This is largely in agreement with the trend expected from thermodynamic considerations. Most of the increase stems from the seasonality of the drivers acting on an increasing oceanic p_CO2 caused by the uptake of anthropogenic CO₂ from the atmosphere. In the high latitudes, the concurrent ocean-acidification-induced changes in the buffer capacity of the ocean enhance this effect. This strengthening of the seasonal winter-to-summer difference pushes the global ocean towards critical thresholds earlier, inducing stress to ocean ecosystems and fisheries⁴. Our study provides observational evidence for this strengthening seasonal difference in the oceanic carbon cycle on a global scale, illustrating the inevitable consequences of anthropogenic CO₂ emissions.

据预测，大气中CO ₂的增加（参考文献¹）会影响全球海洋中无机碳的季节性周期[ ^2,3]，但仍缺乏观测证据来证实这一预测。在这里，使用基于观测值的过去34年间CO ₂（p _CO2）的海洋分压的乘积，我们发现p _CO2的冬夏差异平均增加了2.2±0.4μatm/ m从1982年到2015年的十年间，纬度均为10°。这与热力学方面的预期趋势基本吻合。增长的大部分源于在不断增加的海洋环境中采取行动的驾驶员的季节性p _CO2由大气中人为吸收的CO ₂引起。在高纬度地区，同时发生的海洋酸化引起的海洋缓冲能力变化增强了这种影响。冬季与夏季的季节性差异的这种加强将全球海洋推向更早的临界门槛，对海洋生态系统和渔业造成压力⁴。我们的研究为全球范围内海洋碳循环不断加剧的季节性差异提供了观测证据，从而说明了人为CO ₂排放的必然后果。