Mann Hockey Stick only covered northern hemisphere, other world scientists say medieval warm period was warmer than today, Lord Monckton, WSJ Letter

12/15/11, "The Contrarians Have Better Data," Wall St. Journal, Letter to the Editor, Lord Christopher Monckton

"Prof. Michael E. Mann writes ("Climate Contrarians Ignore Overwhelming Evidence," Letters, Dec. 5) that his 1999 "hockey stick" graph "showed that average temperatures today are higher than they have been for at least the past 1,000 years."

But Mr. Mann's paper only covered the northern hemisphere. It included the questionable use of annual bristlecone-pine tree rings for temperature reconstruction. Even then, it replaced some tree-ring data with estimates. Tree-ring series that showed a 20th-century uptick were given 390 times the weighting of other series, according to a 2005 study by Ross McKitrick, an environmental economist at the University of Guelph. Mr. Mann and his fellow Climategate emailers used what they called "Mann's Nature trick" to "hide" the mismatch between late-20th-century warming and the cooling the tree-rings showed.

Meanwhile, Mr. Mann has often refused to supply programs and data to researchers wishing to verify his work. The 2006 Wegman report for the U.S. House of Representatives showed that many of the papers supporting Mr. Mann's results, which appeared shortly after Mr. McKitrick and his colleague Stephen McIntyre published their exposé of his graph, were written largely by Mr. Mann's associates and co-authors.

The National Academy of Sciences did not, as Mr. Mann says, "affirm" his conclusions, for the data were insufficient. Papers by scientists from all over the world show the medieval warm period that Mr. Mann's work appeared to abolish

• was real, global and warmer than today.

Mr. Mann's questionable result casts doubt on the scientific standards of the Climategate scientists and the U.N.'s Intergovernmental Panel on Climate Change."

via Climate Depot