It is time for my monthly sunspot update, based on the most recent NOAA monthly graph, showing the changes in the Sun’s sunspot activity during September. That graph is below, annotated to show the previous solar cycle predictions and thus provide context.
In September sunspot activity boomed once again, producing the most sunspots in a month since 2016 and ending the slight drop in activity in August to return to the pattern the Sun has exhibited since the end of solar minimum. Consistently the number of sunspots on the visible hemisphere of the Sun since 2020 has exceeded the April 2020 prediction of the NOAA scientist panel, as indicated by the red curve in the graph.
The graph above has been modified to show the predictions of the solar science community for the previous solar maximum. The green curves show the community’s two original predictions from April 2007 for the previous maximum, with half the scientists predicting a very strong maximum and half predicting a weak one. The blue curve is their revised May 2009 prediction. The red curve is the new prediction, first posted by NOAA in April 2020.
The blue curve represents the number of sunspots daily, and shows that the ramp up to solar maximum is continuing to steepen, suggesting that maximum will either arrive a year sooner than predicted, or will be significantly stronger then the prediction should it happen in 2025 as predicted.
The increased activity continues to be in line not with the NOAA panel’s prediction but with the prediction of dissenting solar scientists who have been foretelling a very strong maximum.
Even if those dissenting solar scientists turn out to be correct it really will prove nothing. None of these predictions are based on a true understanding of the fundamental cause for the Sun’s eleven year sunspot cycle. We know the Sun’s magnetic dynamo produces the sunspots and the cycle, but we have no idea why it exhibits this cycle, flipping the polarity of its magnetic field as it does so. Nor do we understand why every few hundred to a thousand years it ceases to produce sunspots and goes through a grand minimum lasting decades.
We also do not know if the intensity of this cycle as well as the arrival of grand minimums has an influence on our climate. There is circumstantial evidence that fewer sunspots leads to a cooler Earth, but the mechanism that links the two has not yet been identified, though there are unproven theories.
That it appears we will not see a grand minimum in the next decade is in a sense a grand shame, as the occurrence of such a rare event would have helped solve these mysteries. Undergoing another typical solar maximum, even if it is weaker or stronger than normal, will provide scientists much less new information. A grand minimum however would have likely made it possible to show without doubt the effect of the sunspot cycle on the Earth’s climate.
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