The modeling of paleoclimate, using physically based tools, is increasingly seen as a strong out-of-sample test of the models that are used for the projection of future climate changes. New to the Coupled Model Intercomparison Project (CMIP6) is the Tier 1 Last Interglacial experiment for 127 000 years ago (lig127k), designed to address the climate responses to stronger orbital forcing than the midHolocene experiment, using the same state-of-the-art models as for the future and following a common experimental protocol. Here we present a first analysis of a multi-model ensemble of 17 climate models, all of which have completed the CMIP6 DECK (Diagnostic, Evaluation and Characterization of Klima) experiments. The equilibrium climate sensitivity (ECS) of these models varies from 1.8 to 5.6 ^∘C. The seasonal character of the insolation anomalies results in strong summer warming over the Northern Hemisphere continents in the lig127k ensemble as compared to the CMIP6 piControl and much-reduced minimum sea ice in the Arctic. The multi-model results indicate enhanced summer monsoonal precipitation in the Northern Hemisphere and reductions in the Southern Hemisphere. These responses are greater in the lig127k than the CMIP6 midHolocene simulations as expected from the larger insolation anomalies at 127 than 6 ka.New synthesis for surface temperature and precipitation, targeted for 127 ka, have been developed for comparison to the multi-model ensemble. The lig127k model ensemble and data reconstructions are in good agreement for summer temperature anomalies over Canada, Scandinavia, and the North Atlantic and for precipitation over the Northern Hemisphere continents. The model–data comparisons and mismatches point to further study of the sensitivity of the simulations to uncertainties in the boundary conditions and of the uncertainties and sparse coverage in current proxy reconstructions.The CMIP6–Paleoclimate Modeling Intercomparison Project (PMIP4) lig127k simulations, in combination with the proxy record, improve our confidence in future projections of monsoons, surface temperature, and Arctic sea ice, thus providing a key target for model evaluation and optimization.

中文翻译：

---

上一次冰间期气候的大规模特征：评估耦合模型比对项目（CMIP6）-古气候模拟比对项目（PMIP4）lig127k模拟的结果

使用基于物理的工具对古气候进行建模，越来越被视为对用于预测未来气候变化的模型的强大的样本外测试。耦合模型比对项目（CMIP6）的新增功能是127 000年前的1级最后一次冰河间实验（lig127k），旨在解决气候对比中全新世更强的轨道强迫的 响应实验，使用与将来相同的最新模型并遵循通用的实验方案。在这里，我们对17个气候模型的多模型集合进行了首次分析，所有这些模型均已完成CMIP6 DECK（克里米亚的诊断，评估和表征）实验。这些模型的平衡气候敏感性（ECS）变化为1.8至5.6  ^∘ C.日晒异常结果在强夏季升温超过在北半球大洲的季节字符lig127k相比于CMIP6合奏piControl北极地区的最低海冰大大减少。多模型结果表明，北半球夏季季风降水增加，南半球夏季风减少。在lig127k中，这些响应比CMIP6中全新世的模拟结果要大，这是 在127处比6 ka处更大的日照异常所预期的。已经开发了针对127 ka的表面温度和降水的新合成方法，用于与多模型集合进行比较。该 lig127k模型集合和数据重建与加拿大，斯堪的纳维亚半岛和北大西洋的夏季温度异常以及北半球各大陆的降水非常吻合。模型与数据的比较和失配表明，需要进一步研究模拟对边界条件中不确定性的敏感性以及当前代理重建中不确定性和稀疏性的敏感性。CMIP6-古气候模拟比对项目（PMIP4）lig127k模拟结合起来借助代理记录，可以提高我们对季风，地表温度和北极海冰未来预测的信心，从而为模型评估和优化提供关键目标。