P2C2: Constraining the Physics that Regulate Equilibrium Climate Sensitivity through Simulation of Last Glacial Maximum (LGM) and Eocene Paleoclimates

该项目旨在调查地球平衡气候敏感性（ECS）的原因和程度。该项目的目标有两个：(1)利用过去冷暖气候、末次极大冰期（LGM）和早始新世的古气候重建，在包括最新的CESM2在内的社区地球系统模型（CESM）系列中约束ECS及其状态依赖性；(2)提供对控制过去和未来ECS的物理的全面机制理解。拟议的工作将包括使用CESM2开发新的LGM和始新世模拟，并将CESM2模拟中的ECS与使用早期版本模型（CESM1.2）进行的现有LGM和始新世模拟进行比较。和CCSM4)，它们有非常不同的物理包。每个模拟将根据代理数据的综合和一个新的古气候再分析产品进行判断，以评估CESM版本的性能并确定ECS的最佳估计。研究人员将使用气候反馈分解和辐射锁定技术来分析这套模拟，以研究在LGM、现在和始新世条件下调节ECS的物理过程。潜在的更广泛的影响包括LGM和始新世的模式模拟，这些模拟将公开提供给广泛的古气候界，以进行进一步的调查和模式数据比较。其他更广泛的影响包括与地球营项目（密歇根大学）合作计划的外展活动，在戴维斯营野外站开发一个实践气候学习模块，旨在扩大代表性不足的少数民族学生对地球科学的参与。此外，该项目将支持培养一名早期职业科学家（博士后研究员）。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project seeks to investigate the causes and magnitude of Earth’s equilibrium climate sensitivity (ECS). The goal of the proposed project is twofold: (1) to use paleoclimate reconstructions of past cold and warm climates, the Last Glacial Maximum (LGM) and Early Eocene, to constrain ECS and its state dependence in the Community Earth System Model (CESM) series including the latest CESM2, and (2) to provide a comprehensive mechanistic understanding of the physics that govern past and future ECS. The proposed work will include development of new LGM and Eocene simulations using CESM2 and comparison of ECS in CESM2 simulations with existing LGM and Eocene simulations performed with earlier versions of the model (CESM1.2. and CCSM4) that have very different physics packages. Each simulation will be judged against a synthesis of proxy data and a new paleoclimate reanalysis product in order to evaluate the performance of the CESM versions and to identify the best estimate of ECS. The researchers will analyze this suite of simulations using climate feedback decomposition and radiative locking techniques to investigate the physical processes that regulate ECS under LGM, present, and Eocene conditions. The potential Broader Impacts include model simulations of the LGM and Eocene that would be made publicly available for the broad paleoclimate community for further investigation and model-data comparisons. Other Broader Impacts include outreach activities planned in collaboration with the Earth Camp Program (University of Michigan) to develop a hands-on climate learning module at Camp Davies Field station with the aim to broaden participation of underrepresented minority students in the Earth Sciences. In addition, the project will support the training of an early career scientist (Post-doctoral researcher).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.