Who erased the medieval heat interval? Tracks result in the College of Bern – is that padded?

From the NoTricksZone

By P. Gosselin on September 2, 2021

Science scandal: What follows is an excellent rundown of how the Medieval Warm Period once again disappeared from the latest IPCC climate report.


Written by: a The Cold Sun Scientist / IPCC 6th Report Reviewer
(Translation, edited and subheadings by P. Gosselin)

The latest UN report skews climate history. The tracks lead to Bern, Switzerland.

In the Middle Ages it was just as warm in Switzerland and other parts of Central Europe as it is today. The so-called Medieval Warm Period (MWP) is scientifically well documented in the region: Between 800 and 1300 AD, many Alpine glaciers shrank dramatically and some were even shorter than they are today. The tree line has shifted upwards. Permafrost has thawed in high alpine regions, which the ice still has a firm grip on today. Warm temperatures are also clearly evidenced by tree rings, pollen, chironomid fossils, and other geological reconstruction methods.

Controversial temperature curve

For a long time it was assumed that medieval warmth could be a regional, North Atlantic phenomenon. This was not confirmed, however, because the warm phase also occurred in many other regions of the world, for example on the Antarctic Peninsula, in the Andes, in North America, in the Arctic, in the Mediterranean, in East Africa, China and New Zealand.

Peer-reviewed: Medieval Warm Periods Worldwide

Together with professional colleagues, we at Die kalte Sonne have evaluated hundreds of case studies from all over the world over the past few years and published the syntheses continent by continent in peer-reviewed journals.

Three of the publications were cited by the Intergovernmental Panel on Climate Change (IPCC) in its recently published 6th Climate Report. The medieval warmth was followed by a steep drop in temperature worldwide. During the Little Ice Age 1450-1850, the climate cooled to the coldest temperature level in the last ten thousand years.

Glue the hockey stick back together

Unfortunately, one looks in vain for this information in the new IPCC report. In it you raise your own view of the climate history of the last thousand years. In the summary intended for politics, a controversial temperature profile is prominently presented right at the beginning, which gives the impression that there have been only minimal pre-industrial climate changes in the last two millennia. With the start of industrialization around 1850, the curve then raced upwards by more than one degree. This representation is also known as “hockey stick”: The pre-industrial era, which was supposedly uneventful from a climatic point of view, forms the straight shaft of the stick, at the end of which comes the upward-pointing blade of the hockey stick with rapid modern heating. It is therefore a déjà vu, an unnecessary one. the 3. Assessment of the 2001 climate report already contained a similar field hockey stick pattern that was supposed to trick politicians into thinking that today’s warming is unprecedented and therefore entirely human.

Recent paleoclimatological research confirms the medieval warm period

However, over the past two decades paleoclimatology has made great strides and data has been carefully collected. This resulted in more realistic temperature developments with a pronounced medieval warm period and a later Little Ice Age.

The relapse into the old days of hockey sticks is all the more bitter. How could that happen? What were the possible motives for the renewed distortion of climate history?

Why back to the hockey stick? PAGES 2k

The questionable new hockey stick temperature curve comes from the international paleoclimatology group PAGES 2k, whose coordination office is located at the University of Bern in Switzerland. The climate scientist Thomas Stocker, who has been involved in the IPCC reports since 1998, also teaches and researches at this university. In 2015 Stocker even ran for the overall chairmanship of the IPCC, but lost to the South Korean Hoesung Lee, who was just presenting the 6th report by Working Group 1. Stocker is co-author of the IPCC’s Summary for Policymakers of the 3rd Assessment of the Climate, in which the hockey stick played a prominent role.

Dissent in the PAGES-2k group

A good twenty years later, the revived field hockey stick comes from Stocker’s University, where he heads the Institute for Climate and Environmental Physics. Just a stupid coincidence? There are many indications that the new climate curve could have been commissioned for the 6th IPCC report. Five of the nineteen authors of the papers on the new hockey stick curve come from Bern.

But a significant part of the PAGES-2k researchers could not technically support the new hockey stick version and left the group in an argument.

Proof thanks to tree rings

Meanwhile, these dissenting scientists published a competing temperature curve with clear pre-industrial climate changes. Using tree rings, the specialists were able to prove that the summer temperatures in the pre-industrial past had already reached today’s level several times. But the work of Ulf Büntgen of the ETH research institute WSL and colleagues was not included in the IPCC report, although it was published in time for the editorial deadline. Interestingly, the controversial PAGES-2k curve was already included in the first draft of the 6th Climate Report, although the corresponding publication had not even appeared formally.

How could that be? In the second draft of the policy summary, the curve shrunk to postage size, positioned on the edge of a composite larger figure. This was the last version available for comment from the IPCC reviewers, who included a researcher from The Cold Sun. All the more surprising when the field hockey stick picture suddenly appeared in full size in the final version.

IPCC hides controversy over PAGES-2k

The IPCC has withheld from the public that the curve is classified as highly problematic by many experts and reviewers. On the one hand, the new hockey stick contains a lot of outlier data, the use of which is difficult to justify. For example, PAGES-2k integrates a tree ring dataset from the French Maritime Alps, although the authors of the original case study expressly advise against using it for temperature reconstructions. On the other hand, data that demonstrate strong pre-industrial natural climate variability are omitted. Detailed criticisms of the report, which were raised in the review process of the report and formally published in publications, were ignored by the IPCC authors.

It is so easy to rewrite climate history, and hardly anyone notices it. Why is that important? Pre-industrial temperature trends are of great relevance for the attribution of modern climate change to man-made factors on the one hand and natural factors on the other.

Since climate models have only assigned negligible natural climate forcing, they can only generate hockey stick patterns. Every pre-industrial warm or cold phase observed in real life causes problems for the models because they cannot be reproduced. They are designed not to do this in the first place.

Fatally incorrect model calibration

This raises uncomfortable questions about their suitability and usefulness for projecting future climates. Ultimately, these are uncalibrated simulations that should not be released for future modeling at all as long as they still fail due to the climate of the past. In reality, predicting the future is probably similarly absurd.

It is particularly peculiar that the climate models of the so-called CMIP6 type that were specially created for the 6th climate report turned out to be largely unusable. Due to cloud modeling errors, they provided temperature curves that were far too hot. Therefore, the IPCC declared that in the current 6th report it would place more emphasis on historical temperature developments.

Inconvenient problems

But since this is also – as described – very controversial, the IPCC is now virtually flattening its replacement tire. In its official press releases, the IPCC largely leaves out these uncomfortable topics. And the public does not hear about it in most media reports either.

Political tactics undermine science

This means that scientific integrity falls by the wayside. It is only a matter of time before critical climate scientists systematically address the inconsistencies in the filtered 6th IPCC climate report. The incident shows how political tactics undermine the scientific integrity of the IPCC and further undermine trust in the institution.

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Climate researcher Thomas Stocker declined to comment when asked by WELTWOCHE. This article first appeared in WELTWOCHE Zurich: Die Weltwoche, No. 33 (2021) | August 19, 2021. (Subtitles added by NoTricksZone)

See also:
– Pages-2k refutation
– MWP card
– 200 non-hockey stick charts


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