Steven McIntyre vs. the Brood of Yamal – Watt with it?

A delight for climate wars veterans, Stephen McIntyre’s tweet thread has revived the topic, or at least the region of the enchanted larch of Yamal.

For those catching up or wanting a refresher, here’s the post that caused much hilarity and unacknowledged embarrassment for the climate consensus community.

If you want to see a variety of posts on this topic, use this search term in your favorite search engine.

enchanted larch from Yamal

And here’s the latest Twitter thread.

Originally tweeted by Stephen McIntyre (@ClimateAudit) on August 30, 2022.

Last week a new article… on Yamal tree rings, co-authored by East Anglian Osborn and Melvin, claimed “the recent Siberian warming that has occurred in the was unprecedented in the past 7 millennia”. @climateofgavin chuckled because the results are similar to the previous UEA.

Schmidt illustrated his giggles with dramatic-looking hockey sticks by Hantemirov (Nature 2022). Neither Schmidt nor Nature showed an even more remarkable figure from the Hantemirov thesis, showing remarkable southward movement of the Yamal tree line through the Holocene with tiny recent HS

The dramatic southward movement of the Yamal tree line in the Holocene (observed by Hantemirov) is consistent with the long-term decline in Greenland’s d18O values ​​(Vinther 2009).

Hantermirov (or Schmidt) also disagrees with the seminal finding of Esper et al (Nature 2012), the lack of responsiveness of the tree show ring chronologies of the tremendous changes in high-latitude JJA irradiance over the Holocene (up to 48 wm-2 vs. 1.5 wm-2 CO2 forcing)

despite the statement in Nature on the supposed availability of data, Hantemirov (2022) has NOT archived the underlying measurement data. About 600 of the ~1600 cores were previously used in Briffa et al (2002, 2009, 2013) and grudgingly made available.

There is some new and interesting information in Hantemirov (2022) – long sought data on sample lat longs – see Samples tab on the table below

Hantemirov illustrated the locations of their samples in the figure below (showing locations on the Tanlova, Khadyta, Yada and Portsa rivers). The color sample shows no distorting pattern.

Here is my plot of the same location data colored by time period – blue oldest subfossil, red modern (living in 1980-2020). An obvious point: modern samples are far south of the range, oldest samples to the north. Note a very old Yuribey river sample to the north, not shown in Nature

another plot of the same location data showing latitude versus core (start) year. The modern tree line is well south of the Holocene tree lines, and modern (living) samples have been collected south of the majority of the mid-Holocene samples. Note early report of early Holocene 70N tree line

Schmidt and other publicists show the heavily smoothed version of the Yamal data. The unsmoothed version is (unsurprisingly) a lot less dramatic.

I was able to replicate their Lowess100 Smooth (from the KMean_Reconstruction series) in the Kmean tab of the archived spreadsheet on the first try (a Wordle eagle so to speak) using Lowess Span f=100/7368. So I can pretty much annotate similar spline smooths they show.

the KMean_Reconstruction is linear (100% correlation) to the underlying CRN as shown below. The Blade of the Smooth begins around 1750 and on the obverse simply shows the ongoing trend of the last few decades, which started around 1750.

in detail, recent “chronology” values ​​(from the southern part of Yamal) are slightly elevated from values ​​earlier in the 20th and late 19th, but no particular HS.

and of course Hantemirov and his East Anglian co-authors made NO attempt to distinguish any additional growth at Yamal resulting directly from late 20th century CO2 “greening”, although such greening at Yamal coincided with most others locations is shown

Originally tweeted by Stephen McIntyre (@ClimateAudit) on August 30, 2022.

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