The Mid-Pleistocene Transition (MPT), where the Pleistocene glacial cycles changed from 41 to ∼100 kyr periodicity, is one of the most intriguing unsolved issues in the field of paleoclimatology. Over the course of over four decades of research, several different physical mechanisms have been proposed to explain the MPT, involving non-linear feedbacks between ice sheets and the global climate, the solid Earth, ocean circulation, and the carbon cycle. Here, we review these different mechanisms, comparing how each of them relates to the others, and to the currently available observational evidence. Based on this discussion, we identify the most important gaps in our current understanding of the MPT. We discuss how new model experiments, which focus on the quantitative differences between the different physical mechanisms, could help fill these gaps. The results of those experiments could help interpret available proxy evidence, as well as new evidence that is expected to become available.

中文翻译：

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中更新世过渡的成因

中更新世过渡 (MPT)，其中更新世冰川周期从 41 到 100 kyr 周期变化，是古气候学领域最有趣的未解决问题之一。在四十多年的研究过程中，已经提出了几种不同的物理机制来解释 MPT，包括冰盖与全球气候、固体地球、海洋环流和碳循环之间的非线性反馈。在这里，我们回顾了这些不同的机制，比较了每个机制与其他机制的关系，以及当前可用的观察证据。基于此讨论，我们确定了我们目前对 MPT 的理解中最重要的差距。我们讨论了关注不同物理机制之间数量差异的新模型实验如何帮助填补这些空白。