Earth system models show wide disagreement when simulating the climate of the continents at the Last Glacial Maximum (LGM). This disagreement may be related to a variety of factors, including model resolution and an incomplete representation of Earth system processes. To assess the importance of resolution and land–atmosphere feedbacks on the climate of Europe, we performed an iterative asynchronously coupled land–atmosphere modelling experiment that combined a global climate model, a regional climate model, and a dynamic vegetation model. The regional climate and land cover models were run at high (18 km) resolution over a domain covering the ice-free regions of Europe. Asynchronous coupling between the regional climate model and the vegetation model showed that the land–atmosphere coupling achieves quasi-equilibrium after four iterations. Modelled climate and land cover agree reasonably well with independent reconstructions based on pollen and other paleoenvironmental proxies. To assess the importance of land cover on the LGM climate of Europe, we performed a sensitivity simulation where we used LGM climate but present-day (PD) land cover. Using LGM climate and land cover leads to colder and drier summer conditions around the Alps and warmer and drier climate in southeastern Europe compared to LGM climate determined by PD land cover. This finding demonstrates that LGM land cover plays an important role in regulating the regional climate. Therefore, realistic glacial land cover estimates are needed to accurately simulate regional glacial climate states in areas with interplays between complex topography, large ice sheets, and diverse land cover, as observed in Europe.

中文翻译：

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土地覆盖在欧洲冰川气候中的作用

在模拟末次盛冰期 (LGM) 的大陆气候时，地球系统模型显示出广泛的分歧。这种分歧可能与多种因素有关，包括模型分辨率和地球系统过程的不完整表示。为了评估分辨率和陆地-大气反馈对欧洲气候的重要性，我们进行了一个迭代异步耦合陆地-大气建模实验，该实验结合了全球气候模型、区域气候模型和动态植被模型。区域气候和土地覆盖模型在覆盖欧洲无冰地区的区域上以高（18 公里）分辨率运行。区域气候模式与植被模式的异步耦合表明，陆气耦合经过四次迭代达到准平衡。模拟的气候和土地覆盖与基于花粉和其他古环境代理的独立重建相当吻合。为了评估土地覆盖对欧洲 LGM 气候的重要性，我们进行了敏感性模拟，我们使用了 LGM 气候但使用了现代 (PD) 土地覆盖。与由 PD 土地覆盖确定的 LGM 气候相比，使用 LGM 气候和土地覆盖会导致阿尔卑斯山周围的夏季更冷、更干燥，而东南欧的气候更温暖、更干燥。这一发现表明 LGM 土地覆盖在调节区域气候方面发挥着重要作用。因此，需要真实的冰川土地覆盖估计来准确模拟欧洲观察到的复杂地形、大冰盖和多样化土地覆盖之间相互作用的地区的区域冰川气候状态。