Migrations of the intertropical convergence zone (ITCZ) have significant impacts on tropical climate and society. Here we examine the ITCZ migration caused by CO₂ increase using climate model simulations. During the first one to two decades, we find a northward ITCZ displacement primarily related to an anomalous southward atmospheric cross-equatorial energy transport. Over the next hundreds or thousands of years, the ITCZ moves south. This long-term migration is linked to delayed surface warming and reduced ocean heat uptake in the Southern Ocean, which alters the interhemispheric asymmetry of ocean heat uptake and creates a northward atmospheric cross-equatorial energy transport anomaly. The southward ITCZ shift, however, is reduced by changes in the net energy input to the atmosphere at the equator by about two-fifths. Our findings highlight the importance of Southern Ocean heat uptake to long-term ITCZ evolution by showing that the (quasi-)equilibrium ITCZ response is opposite to the transient ITCZ response.

热带辐合带（ITCZ）的迁移对热带气候和社会产生重大影响。在这里，我们使用气候模型模拟来研究由 CO ₂ 增加引起的 ITCZ 迁移。在最初的一到二十年里，我们发现向北的 ITCZ 位移主要与异常向南的大气跨赤道能量传输有关。在接下来的数百年或数千年中，ITCZ 向南移动。这种长期迁移与南大洋表面变暖的延迟和海洋热量吸收的减少有关，这改变了海洋热量吸收的半球间不对称性，并造成向北的大气跨赤道能量输送异常。然而，向南的 ITCZ 移动因赤道大气净能量输入的变化而减少了约五分之二。我们的研究结果表明，（准）平衡 ITCZ 响应与瞬态 ITCZ 响应相反，强调了南大洋热量吸收对长期 ITCZ 演化的重要性。