CMG COLLABORATIVE RESEARCH: Development of Bayesian Hierarchical Models to reconstruct climate over the past millennium

曲棍球棒之争是对过去一千年来北方半球平均地表温度变化的重建估计的科学争议。该项目是一个由统计学、科学计算、古气候代理、温度场重建和气候建模专家组成的团队之间的合作，以更好地评估过去温度重建的不确定性，如曲棍球棒图所示（该图显示了可以说是平坦的20世纪前，随后是过去100年的强烈变暖趋势）。关于曲棍球棒图的争论的社会政治意义集中在它作为明确的、由人为原因引起的全球变暖的证据的一部分的使用上。更广泛的社区争议的几个方面集中在对统计方法和创建图表所用数据集的有效性的批评和辩护。这项工作将寻求通过使用贝叶斯分层模型（BHM）组合它们的信息，将已知具有不同时间特征和不确定性的几种代理气候记录纳入古温度重建中。BHM框架有利于将代用数据（例如树木年轮宽度）中的观测误差与感兴趣的潜在物理过程（例如过去的地表温度）隔离开来，从而改善上个千年的气候重建。

The hockey stick controversy is a scientific dispute over reconstructed estimates of the mean surface temperature changes experienced in the Northern Hemisphere over the past one thousand years. This project is a collaboration between a team of experts in statistics, scientific computation, paleoclimate proxies, temperature field reconstruction, and climate modeling to better evaluate the uncertainty of past temperature reconstructions, as exemplified by the hockey stick graph (which shows an arguably flat pre-20th century followed by a strong warming trend over the past 100years). The socio- political significance of the controversy over the hockey stick graph centers on its use as part of the evidence for unambiguous, anthropogenically caused, global warming. Several aspects of the broader community dispute centered on criticism and defense of both the statistical methodologies and the validity of data sets used in creating the graph. This work will seek to incorporate several proxy climate records, which are known to have differing temporal characteristics and uncertainties, into paleotemperature reconstructions by combining their information using Bayesian Hierarchical Models (BHM). A BHM framework is favorable in isolating observational errors in proxy data (e.g. tree ring widths) from the underlying physical processes of interest (e.g. past surface temperature) thus improving climate reconstructions of the last millennium.