We were reminded recently of a discussion on Twitter/X nearly a year ago involving hockey stick slayer Steve McIntyre and several anonymous math geeks who had figured out the latest IPCC trick for making hockey sticks out of nothing. A new blog post at Judith Curry’s Climate Etc., by a young writer who goes by the name haakonsk, reviews the new 2,000-year long hockey stick graph in the last IPCC report in this light. The whole post is worth reading, especially because he digs up some honest quotations from experts in the field who objected to the IPCC cherry-picking evidence, understating uncertainties, etc. He also shows how McIntyre & co. did some remarkable data sleuthing on the latest batch of tree ring chronologies that, in their raw form, have no trend at all, but after “processing” display a sharp upward blade in their last few years. What’s more, after diagnosing a flaw in the processing, McIntyre & co. offered a simple devastating proof that the blade was an artifact. They chopped off the last 25 years of the tree ring data, removing the current blade altogether, then they re-ran the algorithm. Bingo, the computer stuck the same blade back on, just shifted back 25 years. The computers are programmed to find a hockey stick shape in any data whatsoever. They would even put one in the supposedly non-existent Medieval Warm Period if you asked them to. Which is not how science is done. Or at least not how it should be.

Here’s the currently fashionable “processed” record that edges up after 1910 but has a sharp hockey stick blade from 1960 to 1980:

Picture what that graph would look like if you chopped off the last 25 years. Pretty much flat with considerable natural variability, right? Well, yes and no, because after figuring out the processing algorithm McIntyre and co. did that and re-ran the program. Instead of cutting off the blade, it just generated an even taller one 25 years earlier:

Aaaaaack. Devastating man-made warning in the mid-20^th century. Horrible extreme weather, crop failure and mass extinction. We are all going to die. Except it’s a pure artifact.

To make matters worse, or better if you dislike manufactured panics, the same test worked equally well cutting 50 years off.

What was the flaw that led to this scientifically disastrous result? Well, the climate “scientists” would take the raw tree ring records then apply an averaging process to get a second series which was a smoothed version of the first one, but one in which the smoothing process tended to push the last part down towards zero. Then they would divide the raw series by the smoothed one and repeat the process over and over until it stopped changing.

What they apparently didn’t notice, and if they did notice they didn’t object, was that with each repetition the smoothed series was getting lower and lower at the most recent end, and as the denominator series went to zero, the ratio would go higher and higher, creating a phony blade. McIntyre showed an example of a series going through 20 iterations, starting (V1) with no blade at all and ending (V20) as a nice scary hockey stick:

McIntyre also gave an example of how the new method yielded the desired hockey stick shape (top) but using a conventional method on the same data yielded a completely different picture, namely a cooling trend in the 20th century (bottom):

While not every set of tree ring data could be coerced into generating a fake hockey stick, enough of them could be that when the IPCC assembled their graph the fake blades gave them the result they were looking for:

The takeaway from all this high-sticking? That however much you doubt the methods as well as the results of orthodox climate “science”, it’s not enough.