Who erased the medieval warm period - SL

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Who erased the medieval warm period?

In the latest UN report, climate history was distorted.

The tracks lead to Bern.

Sebastian Luening August 28, 2021 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 is scientifically well documented in the region: Between 800 and 1300 AD, many alpine glaciers shrank dramatically and in some cases were even shorter than they are today. The tree line shifted upwards. The permafrost thawed in high alpine regions that are still firmly in the grip of the ice. The

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warm temperatures are also clearly documented by tree rings, pollen, mosquito 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. However, this has not been confirmed, because the warm phase also existed 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. Together with specialist colleagues, I have evaluated hundreds of case studies from all over the world over the past few years and published the syntheses in peer-reviewed journals on a continent-by-continent basis.

Three of the publications have now even been cited by the Intergovernmental Panel on Climate Change (IPCC) in its recently published 6th Climate Status Report. The medieval warmth was followed by a global sudden drop in temperature. During the Little Ice Age, 1450–1850, the climate cooled down to the coldest temperature level in the last ten thousand years.

Unfortunately, one looks in vain for this information in the new IPCC report. It maintains its own perspective on the history of the climate over the past thousand years.

In the summary intended for politicians, a controversial temperature curve is clearly visible right from the start, 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 shot up like a rocket by more than one degree.

This method of representation is also known as a “hockey stick”: the pre-industrial era, allegedly uneventful from a climatic point of view, forms the straight shaft, and at the end of this, with the rapid modern warming, comes the hockey stick's blade. It is therefore a déjà vu, an unnecessary one. A similar hockey stick pattern was already included in the 3rd climate status report from 2001 , which was supposed to lead politicians to believe that today's warming has never happened and is therefore completely human-caused.

In the last two decades, however, paleoclimatology made great strides and data was collected diligently. From this, more realistic temperature developments were created, with a pronounced medieval warm period and later Little Ice Age. The relapse into the old days of hockey stick is all the more bitter. How did this happen? What were the possible reasons for the renewed distortion of climate history?

The questionable new hockey stick temperature curve comes from the international palaeoclimatologist group PAGES 2k, whose coordination office is located at the University of Bern. The climate scientist Thomas Stocker, who has been involved in the reports of the IPCC since 1998, also teaches and researches at this university. In 2015 Stocker even ran for the overall chairmanship of the IPCC, but was defeated by the South Korean Hoesung Lee, who has just presented the 6th report of Working Group 1.

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Stocker co-authored the summary for politicians of the 3rd IPCC Climate Status Report, in which the hockey stick played a central role.

A good twenty years later, the resurfaced hockey stick comes from Stocker's University, where he heads the department for climate and environmental physics. Just a stupid coincidence? There are many indications that the new climate curve may have been commissioned for the 6th IPCC report. Five of the nineteen authors of the articles on the new hockey stick curve come from Bern.

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

Proof thanks to tree rings The dropouts have now published a competing temperature curve with clear preindustrial climatic fluctuations. On the basis of 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. The work of Ulf Büntgen from the ETH Research Institute WSL and colleagues was not included in the IPCC report, although it was published in good time before 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 yet appeared formally. How can that be? In the second draft of the summary for politicians, the curve then shrank to the size of a postage stamp,positioned at the edge of a composite larger image. This was the last version available for comment by the IPCC reviewers, of which I am a member. It was all the more surprising when the hockey stick image suddenly appeared in full size in the final version.

The laws of leverage apply The IPCC withholds from the public that many experts and appraisers see the curve as highly problematic. On the one hand, the new hockey stick contains a whole series of outlier data, the use of which is difficult to justify. For example, PAGES 2k integrates a construction ring data set from the French Maritime Alps, although the authors of the original case study explicitly advise against using them for temperature reconstructions.

On the other hand, data are omitted that prove a strong pre-industrial natural climate variability. The IPCC authors ignored detailed criticism that was exercised in the review process of the report and formally published in publications.

In view of this behavior, an assessment procedure makes little sense. The basic problem: Both IPCC authors and review editors are determined by a politically elected IPCC board. Already in the selection of the researchers involved in the IPCC report, a substantive line of thought is cemented that can hardly be softened later. The laws of leverage apply: Those who sit at the longer end prevail.

The arbitrariness of the IPCC is also clear from another example. In the first draft of the report, the Intergovernmental Panel on Climate Change explicitly listed the Medieval 3

Warm Period and the Little Ice Age in a summary table in chapter one of the “Scientific Basics”. The false reference that it was a North Atlantic, regionally restricted phenomenon was removed in the second draft as a reaction to expert criticism. In the final version, which could no longer be viewed by the reviewers, there was an abrupt Uturn: Both the Medieval Warm Period and the Little Ice Age were secretly, quietly and quietly removed from the table and by a meaningless text under the collective term "The last millennium" exchanged. Three little asterisks explain to the reader equipped with reading glasses that one does not want to use the terms “Medieval Warm Period” and “Little Ice Age” in the report because they are allegedly too poorly defined and regionally variable.

It's that easy to rewrite climate history, and hardly anyone notices it. Why is that important? The pre-industrial temperature development is of the greatest relevance for the division (“attribution”) of modern climate change into man-made and natural factors on the other.

Since the climate models only have negligible natural climate forcing, they can only generate hockey stick patterns. Every pre-industrial warm or cold phase that has actually been determined causes problems for the models because they cannot reproduce them. They are designed in such a way that this is not intended.

This raises uncomfortable questions about their suitability and usability for future climate development. Ultimately, it is a question of uncalibrated simulations that should not actually have been released for future modeling as long as they still fail due to the climate past. In other words: If a climate model provides answers to the question of what the past was like that are miles away from reality, the prognosis of the future will probably be similarly absurd.

It is particularly curious that the climate models of the so-called type CMIP6, created especially for the 6th climate status report, have proven to be largely unusable. Due to cloud modeling errors, the temperature curves were far too hot. Therefore, the IPCC declared that it placed more emphasis on historical temperature developments in the current 6th report.

Inconvenient subjects But since this - as described - is highly controversial, the IPCC is now virtually bursting the spare wheel. In the official press releases, the IPCC largely omits these uncomfortable topics. And even in most media reports, the public does not find out about it.

Scientific sustainability falls by the wayside. Because it is only a matter of time before critical climate scientists will systematically process and address the inconsistencies in the pre-filtered IPCC report. The incident shows how political maneuvering undermines the scientific integrity of the IPCC and undermines the trust placed in the institution.

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=========================================================== Climate researcher Thomas Stocker did not want to take a position when asked by Weltwoche.

Sebastian Lüning is a qualified geoscientist and worked as a reviewer on the IPCC reports “SR15”, “SROCC” and “AR6”. With Fritz Vahrenholt, he wrote the books “Unwanted Truths” and “Unimpeachable: The decision of the Federal Constitutional Court on climate protection in a fact check”. He presents “Climate Show” on YouTube.

This article first appeared in WELTWOCHE Zurich: | World Week , No. 33 (2021) | August 19, 2021 NOTE by John Shanahan, editor of website: allaboutenergy.net: Here are some photos of Switzerland in the last forty years. I’ve observed Switzerland’s climate and nature in all seasons since the 1960s. With Swiss friends, I walked and cross-country skied hundreds of kilometers on beautiful Swiss hiking paths in the valleys and across most mountain ranges. It is one of the most beautiful and well managed countries anywhere. But even the wonderful people of Switzerland have fallen for the anti-fossil fuels, anti-nuclear, catastrophic man-made global warming false alarms. Sad to see the direction politicians, academics, and the media are leading Australia, New Zealand, Europe, and North America. Let these photos of Switzerland taken from 1980 to 2020 tell the real story.

SWITZERLAND - WINTER

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SWITZERLAND - WINTER

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SWITZERLAND -SPRING

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SWITZERLAND - SPRING

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SWITZERLAND - SUMMER

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SWITZERLAND - FALL

We lived in Switzerland for nearly six years in the 1980s and visited it many years since 1962. It is a beautiful country with well managed and maintained infrastructure. I walked and cross-country skied hundreds of kilometers in all regions of the country.

There was no sign of catastrophic man-made global warming disaster now or in the foreseeable future. But many Swiss citizens, Europeans, and North Americans have fallen for these blatant false alarms. So sad for Switzerland and the world.

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