Potsdam climatologist Prof. Stefan Rahmstorf is emerging as an outlier on the claimed polar vortex science behind this past winter’s extreme cold waves in the US and Europe.

German climate site Die kalte Sonne presented its 19th video which looks at Potsdam Institute Professor Stefan Rahmstorf’s claim of polar vortex instability being due to manmade global warming and thus behind the recent cold waves.

Image cropped: Klimaschau

Rahmstorf insists it’s manmade global warming

Rahmstorf claimed in a February online Spiegel article that the cold spells across North America, Europe  and elsewhere were caused by the polar vortex being disrupted by man-made climate change.

Citing climate research done by his former PIK colleague Marlene Kretschmer, now at the University of Reading, Rahmstorf says the examined data from 1979 to 2018 show an increasingly unstable polar vortex.

But Kretschmer tweets: still “lots of uncertainty”

But then on February 16, Ms. Kretschmer tweeted a thread where she seemed to back off a bit on the theory, explaining that “lots of uncertainties” still remain:

Lots of discussions about the recent cold spell, the polar vortex and the role of climate change… Here is my two cents on this:

— Marlene Kretschmer (@Marlene_Climate) February 16, 2021

Need a “better understanding”

Kretschmer concluded at Twitter: “Bottom line: we need a better understanding of the different mechanisms (and associated risks) of how further Arctic changes (which are unfortunately certain in a warming climate) might affect our weather and climate.”

Domeisen, 2019: 170 years of data show no trend

There’s a reason behind Ms. Kretschmer’s reluctance to fully back her former Potsdam Institute colleague, Rahmstorf: A comprehensive publication by Daniela Domeisen, 2019:

Domeisen’s paper presented a chart depicting sudden stratospheric warming events over the past 170 years:

Image cropped: Klimaschau

Domeisen found that there have always been polar vortex fluctuations and abrupt stratospheric warming throughout the long period, and that overall there has been no real detectable frequency trend – a major blow to Rahmstorf.

Rahmstorf misinterprets short term as “long-term”

Kretschmer (and Rahmstorf) focused only on a 39-year period, too short to allow sound conclusions.

 Image cropped: Klimaschau

Kretschmer gets it, but Rahmstorf refuses to acknowledge Domeisen’s results and allows himself to be seduced by pure climate variability and willfully misinterprets the short 39-year trend as a long-term anthropogenic trend.

“Rahmstorf should know better”

“Rahmstorf should know better,” says Die kalte Sonne.

Just a week before Rahmstorf blamed the US and European cold waves on manmade warming on Spiegel Online, the NOAA had issued the following statement:

“No robust trend,” the NOAA found. “Climate models do not agree.”

Domeisen and the NOAA clearly make Rahmstorf the outlier.

Spiegel editor was a former Greenpeace magazine writer

So how did Rahmstorf’s article get by Spiegel’s strict editorial standards? Probably because Spiegel Online deputy chief science editor Kurt Stufenberg used to work many years for Greenpeace magazine.

It’s about activism, not science.

via NoTricksZone

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March 6, 2021 at 10:34AM