State-of-the-art climate models predict the zonal mean mid-latitude circulation will undergo a poleward shift and seasonally and hemispherically dependent intensity changes in the future. Here I review the mechanisms put forward to explain the zonal mean mid-latitude circulation response to increased carbon dioxide (CO₂) concentration. The mechanisms are grouped according to their thermodynamic starting point, which are thought to arise from processes independent of the zonal mean mid-latitude circulation response. There are 24 mechanisms and 8 thermodynamic starting points: (i) increased latent heat release aloft in the tropics, (ii) increased dry static stability and tropopause height outside the tropics, (iii) radiative cooling of the stratosphere, (iv) Hadley cell expansion, (v) increased specific humidity following the Clausius-Clapeyron relation, (vi) cloud radiative effect changes, (vii) turbulent surface heat flux changes, and (viii) decreased surface meridional temperature gradient. I argue progress can be made by testing the thermodynamic starting points. I review recent tests of the increased latent heat release aloft in the tropics starting point, i.e., prescribing diabatic perturbations, quantifying the transient response to an abrupt CO₂ increase and imposing latitudinally dependent CO₂ concentration. Finally, I provide a future outlook for improving our understanding of predicted changes in the zonal mean mid-latitude circulation.

最先进的气候模型预测，未来纬向平均中纬度环流将发生向极地移动以及季节和半球相关的强度变化。在这里，我回顾了为解释纬向平均中纬度环流对二氧化碳 (CO ₂ ) 浓度增加的响应而提出的机制。这些机制根据其热力学起点进行分组，这些起点被认为是由独立于纬向平均中纬度环流响应的过程产生的。有 24 种机制和 8 个热力学起点：(i) 热带地区高空潜热释放增加，(ii) 热带地区以外的干静态稳定性和对流层顶高度增加，(iii) 平流层的辐射冷却，(iv) 哈德利环流圈膨胀，(v) 遵循克劳修斯-克拉佩龙关系的比湿度增加，(vi) 云辐射效应变化，(vii) 湍流表面热通量变化，以及 (viii) 表面经向温度梯度降低。我认为通过测试热力学起点可以取得进展。我回顾了最近在热带起始点对高空潜热释放增加的测试，即规定非绝热扰动、量化对突然 CO ₂增加的瞬态响应以及施加与纬度相关的 CO ₂浓度。最后，我提出了未来展望，以提高我们对纬向平均中纬度环流预测变化的理解。