Every time you hear the claim that this or that year is the “warmest in a thousand years” (or ten thousand or eleventy bazillion) please remember that we have no thermometer records for most of the world before about 1880, so everything prior to that is based on secondary “proxy” indicators like tree ring widths. So be it, it’s the best we can do and with appropriate honesty, caution and humility well worth pursuing. But the wizards of tree ring reconstructions have not told the public that instead they throw out all the data that doesn’t tell them what they want to see. When they collect tree ring samples in the woods and get them back to the lab, they do what they euphemistically call “pre-screening”. They only keep the ones they deem “reliable”, even if it means discarding most of what they collected. And scandalously, “reliable” doesn’t mean methodologically sound. It means confirming the approved narrative of an upward 20th century trend. It’s like a drug trial that only counts data from people who got better. But 20 years ago Stephen McIntyre of hockey stick-busting fame heard about some Alaskan tree ring data being hidden by a scientist named Gordon Jacoby and tried unsuccessfully to get his hands on it. Jacoby died in 2015 and McIntyre just stumbled on an online archive where Jacoby had quietly posted the secret record instead of prudently deleting it. And it blows the IPCC version of climate history to smithereens.
Here is the data, in a form called a Ring Width Index (RWI) which, according to the theory, is a measure of temperature.
If ring widths equal temperature there is a rapid warming after AD 1000 that peaks in the early 1100s then drops into a late 14th century cold era, then cycles in and out of cold periods before concluding in the 1970s on a cold note, the 20th century being nothing out of the ordinary.
It’s clearly an inconvenient data series, and the gatekeepers know it. McIntyre’s post recounts the efforts he made to get Jacoby to release the data, and Jacoby’s remarkable rebuffs, including the appallingly and carelessly frank comment that:
“If we get a good climatic story from a chronology, we write a paper using it. That is our funded mission. It does not make sense to expend efforts on marginal or poor data and it is a waste of funding agency and taxpayer dollars. The rejected data are set aside and not archived...A lesser amount of good data is better without a copious amount of poor data stirred in.”
Which would be quite appropriate if by “poor data” he meant rings from a tree that had been struck by lightning or gnawed by porcupines, so that its growth record didn’t reflect general climatic conditions but specific mishaps affecting only that one plant. But he didn’t. He meant any tree ring series that didn’t show 20th century warming. Verdict first, trial afterward and, in his case, not sufficient tact to pretend he wasn’t engaged in flagrant, even brazen cherry-picking.
The problem with this method is obvious to anyone with statistical training who is not in the climate cult. Suppose tree rings don’t actually measure temperature at all and just randomly wander up and down, as for instance a set of coin tosses carried out over centuries and written down would do. Well, if you sample enough trees, or coin toss records, a few will have a 20th century part that slopes up. If you only use those ones and throw out the rest, you can claim they correlate with temperature and voila, you’ve got a “temperature record” of the past that says what you told it to say, and only what you told it to say.
Likewise if you select a part before the 20th century that is all random noise and has no trend, to confirm your preconceptions, you can claim “the data” shows no warming trend until the past 150 years. By doing so you might well enhance your career prospects. But you’ll have proven nothing scientific: by picking a different subset of the data you could just as easily prove it’s colder now than in the past. Which is precisely what Jacoby’s secret Alaskan record shows.
If it’s a valid temperature proxy, that is. It might not be. But as McIntyre shows, on the usual scientific grounds such as core counts (the number of individual trees sampled) and quality of the location, this series is as valid as others that were used. If it is unreliable, so are they. All tree ring proxies are poor data sets and all must be discarded, and we have to work with others that appear to be more reliable even if they lack precision.
Instead the guardians of orthodoxy cut down the trees they don’t like, and claim the remaining set are the whole forest. And since Jacoby’s series contradicted the nice tidy story, it remained buried until now. And without researchers like McIntyre it would never have seen the light of day, though Jacoby gets some sort of backhanded credit for lacking the cunning to delete it instead of posting it somewhere obscure.
The bottom line is that next time you see a hockey stick graph, remember they threw out most of the data because it didn’t confirm their preconceptions and if you ask to see it they won’t show it to you though if you’re very lucky they’ll drop it somewhere and forget they did. Because science.