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1、过去2000年北半球温度变化重建研究 Temperature reconstruction for the last 2000 years,中国科学院寒区旱区环境与工程研究所,汇 报 提 纲 Contents,一、研究意义(Motivation) 二、资料来源(Proxy records) 三、研究历史、现状(Status) 四、北半球温度序列重建(Our NH reconstruction) 五、存在问题和未来展望,1、Assess climate warming in the 20th century, and reveal climate variability on decadal t
2、o centennial timescales,Combined global land and marine surface temperature record from 1850 to 2007 (from CRU).,一、研究意义(Motivation),2、Improve climate model simulation and reveal forcing mechanisms, and identify relative effect of natural/anthropogenic factors on climate change,Anthropogenic and natu
3、ral forcing factors control climate change during the past 150 years. How to identify the relative contribution of natural and human-induced climate change? The past several millennia encompasses the period before large-scale contamination of the global atmosphere by human activities and global-scal
4、e changes in land-surface conditions. By studying the records of climate variability and forcing mechanisms in the recent past, it is possible to establish how the climate system varied under natural conditions and then detect the effect of human activity on recent climate warming.,3、Project future
5、climate change,Adapted from Mann MK.,汇 报 提 纲 Contents,一、研究意义(Motivation) 二、资料来源(Proxy records) 三、研究历史、现状(Status) 四、北半球温度序列重建(Our NH reconstruction) 五、存在问题和未来展望,二、资料来源(Proxy records),ICE CORES,Restricted to polar and high mountains,CORALS,Restricted to Tropics,TREE RINGS,Dendrochronology,Potential co
6、verage is Widespread.,VARVED LAKE SEDIMENTS,Widespread,HISTORICAL DOCUMENTS,Widespread,汇 报 提 纲 Contents,一、研究意义(Motivation) 二、资料来源(Proxy records) 三、研究历史、现状(Status) 四、北半球温度序列重建(Our NH reconstruction) 五、存在问题和未来展望,三、研究历史、现状(Status),Central England,Jones et al. 1998方法:CPS代用数据:10条分辨率:年树轮、冰芯、历史文献,Mann et a
7、l. 1998, 1999方法:CPS代用数据:12-112条树轮、冰芯、历史文献EOF,Key Points: error bars increase as you go back in time natural variability accounts for 0.5C over the last millennium late 20th century temperature trend is unprecedented,The 20th century surface temperatures were the warmest in the NH in the past 1,000 y
8、ears. The 1990s were the warmest decade and 1998 was the warmest year in the past 1,000 years. There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activity,Intergovernmental Panel on Climate Change (United Nations), Third Assessment Re
9、port, 2001,Esper et al. 2002, Cook et al. 2004 方法:CPS代用数据:6-14条局地序列树轮RCS,(蓝色曲线)Moberg et al. 2005方法:CPS代用数据:18条局地序列树轮、冰芯、历史文献、湖泊沉积小波分析,DArrigo et al. 2006方法:CPS代用数据:19条局地序列树轮RCS,Hegerl et al. 2006,2007方法:CPS代用数据:12条局地序列树轮等多种代用资料total least squares (TLS) regression,It is likely that this 50-year peri
10、od was the warmest Northern Hemisphere period in the last 1.3 kyr. Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations,Intergovernmental Panel on Climate Change (United N
11、ations), Fourth Assessment Report, 2007,Mann et al. 2008,2009方法:CFR正则最大期望法 (RegEM method)代用数据:2109条多种局地序列空间型,Mann et al. 2008,2009;方法:CFR; 正则最大期望法(RegEM method) 代用数据:2109条多种局地序列;空间型. 使用了中国温度重建序列多条(Ge et al., 2003; Wang et al., 1991; Wang et al., 2005; Tan et al., 2003; Zhang et al., 1981),From Frank
12、 et al., 2010,汇 报 提 纲 Contents,一、研究意义(Motivation) 二、资料来源(Proxy records) 三、研究历史、现状(Status) 四、北半球温度序列重建(Our NH reconstruction) 五、存在问题和未来展望,四、北半球温度重建(Our NH reconstruction),所使用的代用资料分布,重建的近千年北半球温度序列,3种方法重建的近千年北半球温度序列,近千年北半球温度序列的比较,汇 报 提 纲 Contents,一、研究意义(Motivation) 二、资料来源(Proxy records) 三、研究历史、现状(Statu
13、s) 四、北半球温度序列重建(Our NH reconstruction) 五、存在问题和未来展望,五、存在问题和未来展望,同一时点各序列间最大相差逾1.0,达序列方差2倍以上;,北半球温度重建结果的差异对比及其不确定性(IPCC,2007),为什么存在如此大的不确定性?长时间序列空间覆盖度不够。以Mann等(08,09)研究为代表,重建过去2000年北半球温度变化仅用20条逾1200年的序列,资料分布不均。长时间序列过少导致重建结果受到质疑。资料指示意义存在不确定性。石笋和沉积气候意义(石花洞)不清晰,树轮则损失了低频和高温信息。重建算法有问题。多元线性回归和经验正交函数。一是假设历史温度空间格局与器测一致;二是方差缩减。,重点应该围绕如何解决资料,即长尺度代用资料可靠性及其空间覆盖度问题,集成算法问题。 1)获取空间覆盖度充足、可靠的长尺度代用资料; 2)提高诊断水平,减少代用资料指示意义不确定性; 3)改进重建方法; 4)关注中世纪、小冰期变化特征,评估20世纪增暖成因;,未来展望:,Thank you,Acknowledgements: 感谢葛全胜、郑景云、谭明等的有益讨论。 感谢: 中国科学院百人计划项目 国家重大科学研究计划973项目“过去2000 年全球典型暖期的形成机制及其影响研究” 国家自然科学基金项目,