Changes

One of the main pieces of evidence for anthropogenic global warming presented during the 3rd IPCC report was a temperature reconstruction done by climatologist [[Michael Mann]]. The resulting graph of the Northern Hemisphere temperature is shaped like a hockey stick, and it is used as evidence for the unusualness of the earth's temperature in the past few decades.   

One of the main pieces of evidence for anthropogenic global warming presented during the 3rd IPCC report was a temperature reconstruction done by climatologist [[Michael Mann]]. The resulting graph of the Northern Hemisphere temperature is shaped like a hockey stick, and it is used as evidence for the unusualness of the earth's temperature in the past few decades.   

While dramatic, the graph encountered serious questions from the beginning.  It failed to reproduce two Northern Hemisphere climate episodes that were well documented in the literature, the Medieval Warm Period and The Little Ice Age (although it should be noted that these were not global phenomenons, instead being limited only to Europe and Greenland; the Mann diagram concerned global average temperatures).  Concerned about these discrepancies, [[Stephen McIntyre]] and [[Canada|Canadian]] economist Ross McKitrick attempted to reproduce the result and discovered a serious flaw in the statistical methods used to construct the hockey stick graph.  Because of this, the 4th Assessment Report of the IPCC included several different temperature reconstruction methods instead of favoring just one hypothesis.

While dramatic, the graph encountered serious questions from the beginning.  It failed to reproduce two Northern Hemisphere climate episodes that were well documented in the literature, the Medieval Warm Period and The Little Ice Age (it should be noted that these were not global phenomenons, but were limited to Europe and Greenland; the Mann diagram concerned global average temperatures).  Concerned about these discrepancies, [[Stephen McIntyre]] and [[Canada|Canadian]] economist Ross McKitrick attempted to reproduce the result and discovered a serious flaw in the statistical methods used to construct the hockey stick graph.  Because of this, the 4th Assessment Report of the IPCC included several different temperature reconstruction methods instead of favoring just one hypothesis.

==Natural variability of the climate system==

==Natural variability of the climate system==

'Global Warming Now World's Most Boring Topic’ <ref>http://newsbusters.org/node/14167</ref>

'Global Warming Now World's Most Boring Topic’ <ref>http://newsbusters.org/node/14167</ref>

The need to fight "global warming" has become part of the dogma of the green conscience. <ref>http://www.cato.org/pubs/regulation/regv15n2/reg15n2g.html</ref>

The need to fight "global warming" has become part of the dogma of the liberal conscience. <ref>http://www.cato.org/pubs/regulation/regv15n2/reg15n2g.html</ref>

Clearly, "global warming" is a tempting issue for many very important groups to exploit.  

Clearly, "global warming" is a tempting issue for many very important groups to exploit.