Mann addresses the “hide the decline” this way: There is a divergence problem. Temps as measured by tree rings diverge from the surface temp record starting around 1960. (We conjecture as to the cause, but we can’t really explain it.)
Yes, we can
explain it. We just haven’t
proved it.
- The data is “bad.”… The only problem with the data is that it stops correlating with the surface temp record and thus is not suitable for the purpose of their nice tidy story.
Take the scare quotes away and your overlay of assuming motives, and your description is accurate. The data
is bad. Surface temperatures are more reliable than modern tree ring data, otherwise weather stations at airports would be composed of a stand of trees that are sampled every day.
- Jones was justified in deleting the decline because we don’t want to confuse the lay audience. … Jones tried to justify the trick to hide the decline because WMO report was directed at sophisticated scientists.
The trick needs very little justification. It is a good trick.
My point is: No matter the audience, if you are going to use the Briffa series in a spaghetti graph, use all of it.
If the purpose of the graph was to prove the accuracy of various proxies, then I would agree. Then it would be dishonest to suppress bad data. But that was not the subject of the graph.
Your job as a scientist is not to mask uncertainties with tricks.
That depends on whether those uncertainties are important to the subject being discussed.
Both of us agree that the divergence problem creates doubts about the use of tree ring proxies as a measure of temperature. Why does this fact have to be hidden from anyone?
It is not hidden when the subject being discussed is the reliability of proxies.
- Jones was not deceitful in deleting the decline because the world was put on notice of its existence in the Nature article. This is laughable too. There is no Central Notice System in science that exempts one from full disclosure.
Full disclosure only applies to
relevant information. For the graph in question, it was not relevant.
- Note also that Mann justifies Jones’ deletion, but makes no mention of Jones’ splicing, a practice he criticizes in his book. Deleting is wrong for the reasons given, but the splicing is the smoking gun of fraud.
Did the graph say it was composed exclusively of tree ring data? If so, I agree. That was misleading. The graph should only say “temperature anomaly”. Then it would not be a fraud.
You can’t take a tree ring curve and then seamlessly join it to a surface temperature curve, as if they constitute one data set.
Actually, we merge and splice and blend temperature data all the time. The many many surface temperature stations each produce a single data set. Some of them go back in time further than others. Some of them have interruptions. Some of them were moved. But they are spliced and blended with the “trick” of averaging.