Re: Detailed evidence fails to support man-made climate change

[maury <maury@webtexas.com>]

>

> Jim Dukelow wrote:



> Actually, the consensus of atmospheric and climate scientists is pretty well represented by the IPCC Third Assessment Report.

>

> Some excerpts:

> =======================



Maury Siskel responds:



One excerpt Jim supplied was:



"It is likely that the rate and duration of the warming of the 20th Century is larger than any other time during the last 1,000 years.  The 1990s are likely to have been the warmest decade of the millennium in the Northern Hemisphere and 1998 is likely to have been the warmest year."



Apparently this refers to the Mann, et al. so-called hockey stick temperature record over the last 1000 years -- reasonably stable from 1000 to 1900 followed by a huge increase from 1900 to 2000. One question might be: if the present is the hottest in the last thousand years, what raised the the temperature to the second hottest before 1000 AD? The error variance in the Mann et al study is so large that many interpretations could be accomodated, as noted below.



Further problems with the Mann et al data are compiled at:



http://www.greeningearthsociety.org/wca/2003/wca_4bpf.html



which includeds the following:



     "In 1999, Michael Mann, an assistant professor at the University of Virginia, composited a number of studies. He chose only nine that drew on climate information from before 1400. As a result, when he compared those early proxy temperatures with observed temperatures of the last hundred years and traced out an average temperature history back to 1000 A.D., his work “proved” there was no global evidence for the existence of either the Little Ice Age or the Medieval Warm Period. Mann’s “hockey stick” charting of temperature calls into question the synthesis of hundreds of other scientific papers–a synthesis that has been going for some time, as evinced by Sir Hubert Lamb’s profound compendium, Climate Past, Present and Future, published in 1990.

      To Mann’s fans, late-20th century temperatures appear to be anomalous. For them, his work is the basis for the oft-repeated claim that recent decades are the “hottest in the last thousand years.”

      Two Harvard scientists (Willie Soon and Sallie Baliunas) and three coauthors recently inspected a much larger set of the paleoclimatic indicators than did Mann and concluded that both the cold and warm periods were real and that the climate of the 20th century, while warm, isn’t at all unprecedented. This hardly should have come as a surprise based on the voluminous literature available on the subject, but in Washington, DC,

climate science is political dynamite. Inhofe and his committee had the makings of hearing filled with scientific pyrotechnics.

      Are Mann’s research and that of Soon and Baliunas irreconciliable? No. A partial reconciliation actually is possible because Mann’s hockey stick incorporates so few climate histories from the early years that its “error bars” (shown in Figure 1a) are able to accommodate the possibility of a very large Medieval Warm Period.

      But that’s partial reconciliation. Is concordance possible? No. Given the mass of scientific papers on the Little Ice Age, Mann’s study can’t be stretched to allow for the possibility of its existence."



More to follow .....

Maury Siskel  maury@webtexas.com  (Ft Worth expected temp today is 104   <g>)





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