A new release of the Max Planck Institute for Meteorology Earth System Model version 1.2 (MPI‐ESM1.2) is presented. The development focused on correcting errors in and improving the physical processes representation, as well as improving the computational performance, versatility, and overall user friendliness. In addition to new radiation and aerosol parameterizations of the atmosphere, several relatively large, but partly compensating, coding errors in the model's cloud, convection, and turbulence parameterizations were corrected. The representation of land processes was refined by introducing a multilayer soil hydrology scheme, extending the land biogeochemistry to include the nitrogen cycle, replacing the soil and litter decomposition model and improving the representation of wildfires. The ocean biogeochemistry now represents cyanobacteria prognostically in order to capture the response of nitrogen fixation to changing climate conditions and further includes improved detritus settling and numerous other refinements. As something new, in addition to limiting drift and minimizing certain biases, the instrumental record warming was explicitly taken into account during the tuning process. To this end, a very high climate sensitivity of around 7 K caused by low‐level clouds in the tropics as found in an intermediate model version was addressed, as it was not deemed possible to match observed warming otherwise. As a result, the model has a climate sensitivity to a doubling of CO₂ over preindustrial conditions of 2.77 K, maintaining the previously identified highly nonlinear global mean response to increasing CO₂ forcing, which nonetheless can be represented by a simple two‐layer model.

中文翻译：

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MPI-M 地球系统模型 1.2 版 (MPI-ESM1.2) 的发展及其对二氧化碳增加的响应。


马克斯·普朗克气象研究所地球系统模型版本 1.2 (MPI-ESM1.2) 的新版本发布。开发的重点是纠正错误和改进物理过程表示，以及提高计算性能、多功能性和整体用户友好性。除了新的大气辐射和气溶胶参数化之外，模型云、对流和湍流参数化中几个相对较大但部分补偿的编码错误也得到了纠正。通过引入多层土壤水文方案、将土地生物地球化学扩展到包括氮循环、取代土壤和凋落物分解模型以及改进野火的表征，完善了土地过程的表征。海洋生物地球化学现在可以预测蓝藻，以捕获固氮对气候条件变化的反应，并进一步包括改善碎屑沉降和许多其他改进。作为新事物，除了限制漂移和最小化某些偏差之外，在调音过程中还明确考虑了仪器记录变暖。为此，解决了中间模型版本中发现的由热带低层云引起的约 7 K 的非常高的气候敏感性，因为它被认为不可能与观测到的变暖相匹配。因此，该模型对 CO ₂比工业化前条件下 2.77 K 加倍具有气候敏感性，保持了先前确定的对 CO ₂强迫增加的高度非线性全球平均响应，尽管如此，这可以用简单的双层模型来表示。