Prof. Klaus Hasselmann is not the perfect witness to man-made global warming

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By Kalte Sonne

By Thomas Oelschläger:

The current debate on the observed global warming and the economic and technical consequences to be drawn from it, in particular the use of fossil fuels for energy production, is dominated by the view that only the CO2 released due to human activities is responsible for the warming and ultimately for expected catastrophes. From this belief develops the consequence of reducing the release of CO2 to zero as far as possible through a massive social, economic and technical restructuring. Prof. Klaus Hasselmann, who received the Nobel Prize in Physics in autumn 2021 for his work on the detection of a human fingerprint for anthropogenic climate change caused by the burning of fossil fuels, is repeatedly mentioned as one of the key witnesses to this view.

The basis for the award ceremony was a model he developed in the 1970s/80s that combines weather and climate. He developed methods for identifying specific fingerprints left in the climate (?) by natural phenomena on the one hand and by human activities on the other. This is said to have provided proof that the rise in temperature in the atmosphere is solely due to human CO2 emissions. Prof. Hasselmann is interpreted as meaning that only humans caused climate change and therefore natural influences did not play a significant role.

Later works by Prof. Hasselmann, however, raise the question of whether his award-winning works actually contained these statements now attributed to them or whether he later moved away from them. Together with other scientists, he published the paper “Detection and Attribution of Recent Climate Change: A Status Report” in the Bulletin of the American Meteorological Society in December 1999. The results of the work contain the following statements (page 2651):

“The recent changes in global climate inferred from near-surface atmospheric temperatures cannot be readily explained by natural climate variability.”

“Greenhouse warming alone is insufficient to explain the observed pattern of climate change.”

“The most probable cause of the observed warming is a combination of internally and externally forced natural variability and anthropogenic sources. But given the large model uncertainties and limited data, a reliable weighing of the different factors contributing to the observed climate change cannot currently be given.”

“In short, we cannot attribute, at this time, with a high level of statistical significance, the observed changes in global and large-scale regional climate to anthropogenic forcing alone. This result should not come as a great surprise.”

As a result, this means that on the basis of uncertain climate models, no singular causation by humans can be detected, but that both natural and anthropogenic causes are relevant, whereby the respective proportion cannot be determined with certainty.

A review of the broad spectrum of climate science publications and not just the limited range of work in accordance with the content of the IPCC shows that the above assessments are still valid today. In the last twenty years, the evidence on sole human responsibility desired by the climate protection movement has not progressed any further.

Only the media and political dissemination of the claim of the monocausal causation of global warming by anthropogenic CO2 has progressed. In the process, the political and public discussion has largely decoupled from the basic scientific question and an atmosphere of intolerance towards positions beyond the prevailing opinion has emerged. Even the representation of a position such as that of Prof. Hasselmann et al in 1999 is likely to be sharply criticized today by activists, the media and parts of politics and rejected as inadmissible.

The cited results of Prof. Hasselmann are still represented by many serious scientists and institutions with thoroughly developed arguments. In recent years, numerous works have been published, which e.g.

  • critically question the increase of the atmospheric CO2 content to over 415 ppm exclusively by anthropogenic CO2 and question the model of the carbon cycle used by the IPCC
  • assess the climate sensitivity of CO2 significantly lower than the IPCC,
  • attach decisive importance to the role of clouds, or
  • describe the influence of the ocean cycles AMO and PDO on the warming of the atmosphere.

There can therefore be no question of “the science being clear”, especially since the study by Cook, which forms the basis of this myth, has obviously used an unfair statistical deception to achieve the intended result. One must certainly credit Prof. Hasselmann with having developed a methodology that shows a human influence on the atmosphere through the burning of fossil fuels.

Of course, the existence of this human component does not mean that the influence of the earth’s climates by the millennia-long natural climate drives has stopped with the onset of the combustion of fossil substances. In climate research, nothing should be safer than the existence and operation of these natural climate drives. Honest scientists should point out that the proportions of natural and human influences can still not be quantified with certainty.

By 1999 at the latest, Prof. Hasselmann assumed that greenhouse gases were not the sole cause of the observed global warming. Nevertheless, the award of the Nobel Prize to him is celebrated by climate alarmists as confirmation of their belief in the exclusive causation of CO2 for warming. Later statements are hidden because they do not fit into the picture! It is obviously not suitable as a key witness to man-made climate change alone.