In the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2), coupled climate models have been used to simulate an interglacial climate during the mid-Piacenzian warm period (mPWP; 3.264 to 3.025 Ma). Here, we compare the Atlantic Meridional Overturning Circulation (AMOC), poleward ocean heat transport and sea surface warming in the Atlantic simulated with these models. In PlioMIP2, all models simulate an intensified mid-Pliocene AMOC. However, there is no consistent response in the simulated Atlantic ocean heat transport nor in the depth of the Atlantic overturning cell. The models show a large spread in the simulated AMOC maximum, the Atlantic ocean heat transport and the surface warming in the North Atlantic. Although a few models simulate a surface warming of ∼ 8–12 ^∘C in the North Atlantic, similar to the reconstruction from Pliocene Research, Interpretation and Synoptic Mapping (PRISM) version 4, most models appear to underestimate this warming. The large model spread and model–data discrepancies in the PlioMIP2 ensemble do not support the hypothesis that an intensification of the AMOC, together with an increase in northward ocean heat transport, is the dominant mechanism for the mid-Pliocene warm climate over the North Atlantic.

中文翻译：

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在PlioMIP2中模拟的上新世中大西洋经向翻转环流

在上新世模式比对项目第二阶段（PlioMIP2）中，耦合气候模型已被用来模拟在Piacenzian中期暖期（mPWP； 3.264至3.025 Ma）之间的冰川间气候 。在这里，我们比较了用这些模型模拟的大西洋经向翻转环流（AMOC），极地海洋传热和海面变暖。在PlioMIP2中，所有模型都模拟增强的上新世中期AMOC。但是，在模拟的大西洋热传输中以及在大西洋翻转单元的深度中都没有一致的响应。这些模型在模拟的AMOC最大值，大西洋的热传输和北大西洋的地表变暖方面显示出很大的差异。尽管一些模型模拟了约 8–12 的表面升温^∘ Ç在北大西洋，类似于来自新世研究，解释和天气映射（PRISM）4版本的重建，大多数模型似乎低估了这种变暖。PlioMIP2集合中较大的模型传播和模型数据差异不支持以下假设：AMOC的强化以及北海热量传输的增加是北大西洋中上新世温暖气候的主要机制。