P2C2: Paleo Perspectives on Temperature Extremes

为了加深我们对历史和现代极端温度的理解，哈佛大学的研究人员将使用新的统计方法分析过去气候的仪器和温度敏感指标。具体地说，研究人员将探索极端指标和替代指标之间的关系，重建空间和时间上的极端温度，并更好地理解平均气候变化与极端事件发生的关系。分析战略是将现有的贝叶斯方法扩展到更直接地针对极端情况来推断过去的气候。“极端”的定义将符合2006年国家研究委员会为准确量化最大值、最小值或变化率等数量真正例外的概率而制定的标准。根据定义，极端值是罕见的，这使得对记录时间长于仪器本身提供的记录的需要可能比评估平均气候更迫切。该项目的成功完成将有助于深入了解背景气候和极端气候之间在足以确定基线条件的一段时间内的协变性。这项工作还将提供解释和评估现代变化的重要背景。鉴于过去600年来气候变暖和变冷的机制不同，这项研究还将指出，过去平均气候和极端气候之间的关系在多大程度上可以被用作未来变化的类比。除了更好地理解极端事件的社会相关性之外，其他更广泛的影响包括培养研究生和支持没有国家科学基金会先前支持的早期职业研究人员。在这项研究期间开发的所有软件工具将免费向古气候界公开提供，任何公开可获得的数据集的汇编也是如此。

To improve our understanding of historical and modern extreme temperatures, researchers at Harvard University will analyze instrumental and temperature-sensitive proxies of past climate using new statistical approaches. Specifically, the researchers will explore the relationships between instrumental and proxy indicators of extremes, reconstruct temperature extremes in space and time, and provide a better understanding of how changes in mean climate relate to the occurrences of extreme events. The analysis strategy is to extend an existing Bayesian methodology for inferring past climate to more directly target extremes. Definition of "extremes" will meet the standards set forth by the National Research Council in 2006 for accurate quantification of the probability that quantities such as maxima, minima, or rates-of-change are truly exceptional.Extremes are by definition rare, making the need for records longer than are afforded by instruments alone perhaps even more acute than for evaluation of mean climate. Successful completion of this project will provide insight into the co-variability between background climate and extremes over a time period long enough to establish baseline conditions. The work will also provide important context in which to interpret and assess modern changes. Given that disparate mechanisms are responsible for warming and cooling over the last 600 hundred years, this research will also indicate the extent to which past relationships between mean climate and extremes can be used as analogues for future changes.In addition to the societal relevance of better understanding extreme events, other broader impacts include training of a graduate student and support of an early career researcher with no prior NSF support. All software tools developed during this research will be made freely and publicly available to the paleoclimate community, as will any compilations of publicly available data sets.