P2C2: Estimating Climate Sensitivity from Temperature Reconstructions of the Last Glacial Maximum

这是一个利用末次盛冰期（LGM：21，000年前）的古气候重建和各种气候模型来评估平衡气候敏感性的项目。 Schmittner-Boesch在2011年发表了一篇有影响力的论文，指出地质学证据表明，平衡气候对大气CO2加倍的敏感性为1.4至2.8 C，低于IPCC 4可能的范围2至4.5 C，地质学数据排除了对CO2加倍的非常高的敏感性。 然而，有几个问题尚未解决。 例如，LGM的几个不同的古气候重建产生不同的全球温度的平均降低，这对敏感性估计有很大的影响。 此外，古气候重建的误差范围很大，这种误差对气候敏感性的影响需要更好地量化。 最后，初步研究进行了“减少复杂性”的气候模式。 尚不清楚模型的选择对结果的影响程度。 该项目将通过扩大研究中使用的古气候重建并纳入LGM完全耦合气候模型模拟的输出来进一步评估这些问题。 一些新的LGM重建已经出版，现在可供分析。 通过使用新的CMIP 5/PMIP 3模式--具有特定的LGM边界条件/重建--现在可以通过用CMIP 5/PMIP 3模式结果的输出约束简化的模式，以更严格的方式进行平衡气候敏感性的分析。该项目将支持来自俄勒冈州州立大学的气候模拟师，他将与普林斯顿大学伍德罗·威尔逊公共和国际事务学院的一位统计学家合作。 该项目包括对博士后研究人员的指导和培训。

This is a project to use paleoclimate reconstructions of the Last Glacial Maximum (LGM: 21,000 years ago) and a variety of climate models to evaluate equilibrium climate sensitivity. Schmittner-Boesch published an influential paper in 2011 suggesting that the geological evidence implied an equilibrium climate sensitivity to a doubling of atmospheric CO2 of 1.4 to 2.8 C, lower than the IPCC4 likely range of 2 to 4.5 C and that the geological data ruled out very high sensitivities to doubling of CO2. However there were several issues left unresolved. For instance, several different paleoclimate reconstructions of the LGM produce different average reductions in global temperatures, which have a big effect of the sensitivity estimates. In addition, the range of error on the paleoclimate reconstructions is large and the effects of this error on the climate sensitivity need to be better quantified. Finally the initial study was performed with a "reduce-complexity" climate model. It was not clear the extent to which the result was affected by choice of model. This project will further evaluate these issues by expanding the paleoclimate reconstructions used in the study and incorporating the output from fully coupled climate model simulations of the LGM. Several new reconstructions of the LGM have been published and are now available for analysis. With access to the new CMIP5/PMIP3 models - with specific LGM boundary conditions/reconstructions - it is now possible to perform the analysis of equilibrium climate sensitivity in a more rigorous way by constraining the reduced-complexity model with output from the CMIP5/PMIP3 model results.This project will support a climate modeler from Oregon State University, who will collaborate with a statistician from the Woodrow Wilson School of Public and International Affairs at Princeton University. Mentoring and training of a postdoctoral researcher is included in the project.