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阿弥陀佛

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一直从事气象预报、服务建模实践应用。 注重气象物理场、实况场、地理信息、本体知识库、分布式气象内容管理系统建立。 对Barnes客观分析, 小波,计算神经网络、信任传播、贝叶斯推理、专家系统、网络本体语言有一定体会。 一直使用Java、Delphi、Prolog、SQL编程。

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So How Have Global Temperatures Changed in the Past?  

2012-02-15 15:22:41|  分类: Meteorology |  标签: |举报 |字号 订阅

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So How Have Global Temperatures Changed in the Past?
So How Have Global Temperatures Changed in the Past? - 险峰 - 阿弥陀佛
 
So How Have Global Temperatures Changed in the Past? - 险峰 - 阿弥陀佛
 The temperature changes associated with the Milankovich cycles are demonstrated by analysis of ice cores collected at the research station at Vostok, Antarctica. The ice cores provide a record of atmospheric composition going back in time. Temperature is determined by measuring the deuterium content of the ice at different levels. The following chart shows carbon dioxide content, dust concentration, and Antarctic temperatures going back about 400,000 years.
So How Have Global Temperatures Changed in the Past? - 险峰 - 阿弥陀佛

Antarctic temperature variation is shown on the top graph in blue. Low points are glacial periods, high points are interglacials.

What about the last 1,000 years?

The following chart from a report by the U.S. National Academy of Sciences (NAS) (“Surface Temperature Reconstructions for the Last 2,000 Years,” 2006) shows estimates of global average surface temperatures during about the past 1,100 years.

So How Have Global Temperatures Changed in the Past? - 险峰 - 阿弥陀佛
 
 

NAS says that:

Large-scale surface temperature reconstructions yield a generally consistent picture of temperature trends during the preceding millennium, including relatively warm conditions centered around A.D. 1000 (identified by some as the “Medieval Warm Period”) and a relatively cold period (or “Little Ice Age”) centered around 1700. The existence of a Little Ice Age from roughly 1500 to 1850 is supported by a wide variety of evidence including ice cores, tree rings, borehole temperatures, glacier length records, and historical documents. Evidence for regional warmth during medieval times can be found in a diverse but more limited set of records including ice cores, tree rings, marine sediments, and historical sources from Europe and Asia, but the exact timing and duration of warm periods may have varied from region to region, and the magnitude and geographic extent of the warmth are uncertain.

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