A paper published last June was catnip for those who are keen to explain climate change with something other than man-made greenhouse gas emissions. It was also apparently wrong enough to be withdrawn this week from the magazine that published it, despite the authors' objection.
The conclusion of the paper was that it describes a newly discovered cycle in the movement of the sun that takes us 300 years into a thousand-year warming period for the earth. However, keep in mind that we measured the sun's radiation directly and there was no increase to explain the observed global warming – or that there is no evidence of a 2,000-year temperature cycle in the paleoclimate dataset.
These obvious problems did not prevent some people from considering this study as evidence that warming was natural in the past and that there is only mild and unavoidable warming in our future.
What goes up must come down … in one cycle?
The main author of the paper was Valentina Zharkova, a mathematician and astrophysicist at Northumbria University who has a track record. If you've ever read one of the dozens (hundreds?) Of British tabloids that say we're about to start an upcoming "mini-ice age" driven by a waning solar cycle, it probably was through a quote supported by Professor Zharkova. A mini ice age can of course be difficult to fit into a 1000 year warming trend, but that didn't stop Zharkova from publishing her new claim.
Critique of the work began immediately after her paper was published in Scientific Reports – an open access journal of the extended family that was published under the same roof as Nature. In fact, much of it is documented in a long PubPeer comment thread. A website where a kind of public peer review should take place after publication. (This really incredible thread is recommended for reading, dear reader.)
Objections started with Ken Rice, astrophysicist and climate blogger at Edinburgh University. He questioned the paper's central claim – that the distance between Earth and the Sun would change due to the cycle they described. And here it got really wild.
Zharkova went back and forth with Rice, which generated more heat than light. They both agreed that the sun is known to wobble around the exact gravitational equilibrium point of the solar system, which was slightly detached from its brand due to the attraction of the larger planets such as Jupiter and Saturn. However, the study seemed to ignore the fact that Earth's orbit is also shifting in response to these giant planets, keeping it at a constant distance from the sun. Instead, the paper assumed that Earth's orbit was unaffected, so any movement of the Sun would change its distance from Earth. If not, the amount of sunlight reaching Earth has not changed and there is no mechanism for its centuries-long warming trend.
When several people tried unsuccessfully to point out that this constant earth-sun relationship is known, Zharkova wrote: “Oh dear, do you suggest that Earth follows this solar inertial movement in orbit? And its orbit is not stable? You have to have a very lively idea that the earth moves like a drunk man … (sic) "
After Rice provided a simple orbital simulation to calculate gravitational interactions in the solar system, Zharkova once replied, "Your simulations are extremely biased by the idea you believe in."
(Zharkova also shows an affinity for a number of arguments against the clear evidence of man-made climate change. He shares (without prompting) the claim that humans are not responsible for the increase in atmospheric CO2 levels in the accuracy of global temperature data Question and cannot capture the important difference between local temperature data and global records.)
On Wednesday, scientific reports, for which Zharkova is listed as the editor, officially withdrew the paper. The withdrawal notice states: "Concerns have been expressed regarding the interpretation of the temporal change in the distance between earth and sun, and some of the assumptions on which the analyzes presented in the article are based are incorrect." One of the four authors of the paper apparently agreed to withdraw the paper while the other three (including Zharkova) objected.
When Zharkova was contacted by Retraction Watch about their contribution on the subject, he said to them: "We consider this withdrawal by the publisher of scientific reports to be a shameful step to cover up the truthful facts about the sun and earth orbital movement that it is about withdrawn paper reports Our responses to reviewers' comments and in further papers. "
Correlation is not a reason to celebrate
In a blog post on retreat, NASA climate researcher Gavin Schmidt reflected on the ever-growing catalog of studies that claim to find solar cycles in the Earth's climate. "(T) here is a long story of people who assume that they" know "that solar cycles have an effect, and then look deeper into the mechanism," he writes.
The problem is that if you try enough data sets – for example local and non-global temperatures – you may find the cycle correlation you want. Extrapolating this correlation into the future often makes headlines in outlets that don't know how to cover science, have a penchant for hype, or both.
Schmidt points out that the predictions never seem to change. It turns out that without a lot of physics, math doesn't say much about the behavior of the climate system.
This friction is fully indicated in the PubPeer discussion of this paper. In response to the challenges that the study solar system model contradicts physics, Valentina Zharkova seems to repeatedly argue that her correlation is too good to be wrong. Obviously it doesn't work that way. Correlations generate verifiable hypotheses, and some of these hypotheses will undoubtedly be wrong. The correlation may be explained by something else – including the possibility that the correlation is a meaningless idiosyncrasy of your data set or statistical method.
And in this case, a poorly tested correlation hypothesis was surely unable to knock over the mountainous pile of physically-based evidence that clearly shows that humans caused modern global warming. No matter how much some people liked the sound.