CMG Collaborative Research: Development of Bayesian Hierarchical Models to Reconstruct Climate Over the Past Millenium

曲棍球棒争议是一场科学争议，是对北半球过去1000年来经历的平均表面温度变化的重建估计。这个项目是统计学、科学计算、古气候代理、温度场重建和气候建模专家团队的合作，目的是更好地评估过去温度重建的不确定性，如曲棍球棒图(它显示了20世纪之前可以说是持平的，随后在过去100年里有强烈的变暖趋势)。曲棍球棒曲棍图的争议的社会政治意义集中在它被用作明确的、人类原因造成的全球变暖的证据的一部分。更广泛的社区争议的几个方面集中在对统计方法和用于创建图表的数据集的有效性的批评和辩护上。这项工作将寻求将几个已知具有不同时间特征和不确定性的替代气候记录纳入到古温度重建中，方法是使用贝叶斯分层模型(BHM)合并它们的信息。BHM框架有利于将代理数据(例如树木年轮宽度)中的观测误差与感兴趣的基本物理过程(例如过去的地表温度)隔离开来，从而改进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.