Sunday, January 12, 2014 7:13:32 PM
@ Broizfam: Thanks--although you may be the only one still reading the thread at this point.
I have to say, it's rather difficult to discuss AGW with people on IAB who are not particularly knowledgeable--and it`s not because of what they don`t know. It`s because of the misinformation that they *think* they know that they have picked up from either far-right anti-AGW blogs or Fox News. Usually 90% of my energies--and 100% of the other person`s patience--is spent on dispelling untruths.
The sorry consequence of this is I seldom get a chance to give the other person basic, honest information and resources with which he could start doing his own investigation of the issue, from either a pro-AGW position or an anti-AGW position.
* Since the correlation between temperature and tree rings breaks down after 1960, you might be wondering how tree rings can be trusted as proxy data for much earlier periods. To verify the accuracy of tree rings as a proxy, dendroclimatologists have spent decades comparing them to other proxies such as lake and ocean sediments, ice cores, coral growth, pollen grains, and water isotopes. Those comparisons have confirmed that prior to 1960, the tree ring data are reliable.
** The eight investigations that exonerated the climatologists are: (1) House of Commons Science and Technology Committee (UK); (2) Independent Climate Change Review (UK); (3) International Science Assessment Panel (UK); (4) Penn State University 1st Investigative Panel (US); (5) Penn State University 2nd Investigative Panel (US); (6) United States EPA (US); (7) Department of Commerce (US); and (8) National Science Foundation (US).
Clearly, the idea that Jones was talking about "hiding a decline" in TEMPERATURES since 1961 and 1981 is absurd: accurate, modern-day temperature records abound and there`s no way anyone`s going to hide them, regardless of what direction they`re headed in.
Bear in mind that this simply isn`t my personal interpretation of Jones` email. As I mentioned earlier in this thread, eight separate investigations** have looked into the "Climategate" emails and found no evidence of fraud or scientific misconduct.
The "decline" that is being referred to by Jones is not a decline in temperatures. It`s a decline in the correlation between temperature and tree ring growth that has occurred since about 1960. Prior to 1960, tree rings serve as an excellent proxy for temperature records; post 1960, for reasons that are not well understood but that probably have to do with acid rain and other forms of pollution, they do not.
The problem is so well-known among climatologists it`s usually referred to in shorthand fashion as "the (tree-ring) divergence problem."
What Jones is stating in his email is that he used the same technique that Mann had employed in a *Nature* article of using tree-ring proxy data up to the recent past and then extended the trendline using modern temperature records. Tree-ring data measurements later than 1960, he`s saying, have been dropped from the chart because of the divergence problem.*