This paper generated an enormous thread on @PubPeer where the authors continued to defend the indefensible and even added in new errors (such as a claim that the Earth’s seasonal cycles are due to variations in the Earth-Sun distance). Additionally, it seeded multiple nonsense newspaper articles in the UK and elsewhere (some of which were quietly deleted or corrected).
But the interesting thing is that this cycle of very public solar claim/counter-claim/claim/retraction was totally predictable.
Why is this? What is it about solar-climate links in particular that brings out the confirmation bias and the defend-at-all-costs responses? Why are the UK tabloids so excited about mini-ice age stories?
First off, it has to be clearly said that there is an enormous amount of good work done on this question. People like Judith Lean, Greg Kopp, Jo Haigh, Lesley Gray, Leif Svalgaard have been building better and better records of historical solar activity, improving the calibrations and observations of current measurements, and really drilling down into the mechanisms of possible climate impacts. Second, I have published multiple papers on the topic from a modeling perspective.
But, there has been a long history of people assuming that they *know* that solar cycles have an effect and then just looking every more deeply for the mechanism. Indeed, solar-climate links might be the ur-topic of the current p-hacking scandal that is troubling a lot of science these days.
There must be a pony in there somewhere
This goes back a very long way. Indeed, the first modern “sunspot-climate” claim (published by William Herschel in 1801), was in fact insignificant (Love, 2013), though in Herschel’s defense, statistical significance wasn’t really understood in the late 18th Century.
Slightly more recently, a classic of the genre was published in Science (Friis-Christensen and Lassen, 1991) which not only misrepresented the analysis they did to “prove” a link between climate and “solar-cycle length”, but in correcting it made even more arithmetic errors (Laut, 2003). That this massively cited paper (> 1300 cites) is still unretracted is continuing mystery.
Needless to say, very few (if any) of these solar-climate links are predictive. That is, once new data comes in, the purported correlations evaporate as fast as the credibility of the authors. And yet, the next paper that ‘fixes’ the correlation still gets published. We have, of course, discussed this before.
It’s (not) the sun
Some of this is related to a desire to find something other than human activities as the cause of the climate changes since the late 19th Century. Folks who really, really, really, don’t want climate change to impact societal choices [newsflash, it already has] often grab on to speculative solar effects as a last ditch throw of the uncertainty dice. But obviously, solar-cycle mania predates any of those concerns. For instance, what was Oscar Wilde responding to?
Why does not science, instead of troubling itself about sunspots, which nobody ever saw, or, if they did, ought not to speak about; why does not science busy itself with drainage and sanitary engineering?Oscar Wilde (1882)
These days, the intransigence of climate change contrarians comes as no surprise. So the warm welcome afforded to solar-climate proponents by the GWPF et al is to be expected. But for anyone serious, making whoopee with such strange bedfellows is probably unwise.
It’s a minefield
To anyone who is working on this topic (including me), the conclusion that you must tread carefully is inescapable. The need for self-criticism in the design and publication of results and the importance of real peer review cannot be overstated. The normal human tendencies to rush, or be excited by a new finding, have to be tempered by the knowledge that this has led many authors to make mistakes and be premature (and wrong) in their conclusions. Zharkova et al are merely the latest in a long line of people who have fallen into this trap.
They won’t be the last.
- V.V. Zharkova, S.J. Shepherd, S.I. Zharkov, and E. Popova, "Retraction Note: Oscillations of the baseline of solar magnetic field and solar irradiance on a millennial timescale", Scientific Reports, vol. 10, 2020. http://dx.doi.org/10.1038/s41598-020-61020-3
- J.J. Love, "On the insignificance of Herschel's sunspot correlation", Geophysical Research Letters, vol. 40, pp. 4171-4176, 2013. http://dx.doi.org/10.1002/grl.50846
- E. Friis-Christensen, and K. Lassen, "Length of the Solar Cycle: An Indicator of Solar Activity Closely Associated with Climate", Science, vol. 254, pp. 698-700, 1991. http://dx.doi.org/10.1126/science.254.5032.698
- P. Laut, "Solar activity and terrestrial climate: an analysis of some purported correlations", Journal of Atmospheric and Solar-Terrestrial Physics, vol. 65, pp. 801-812, 2003. http://dx.doi.org/10.1016/S1364-6826(03)00041-5