It is sunspot update time again! NOAA today updated its monthly graph for tracking the Sun’s monthly sunspot activity, and I have posted it below, with additional annotations by me to show the past solar cycle predictions.
July and August had seen sunspot numbers higher than the new NOAA prediction (shown by the red curve on the graph below). September however was almost totally blank, with only two weak sunspots for the entire month, as shown on the SILSO graph below.
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.
Both however had polarities assigning them to the upcoming maximum. We have now gone almost three months with no sunspots with the previous maximum’s polarity. These two facts reinforce the conclusion reached by NOAA scientists two weeks ago that the ramp up to the next maximum has started, and that the slowly ending minimum reached its nadir in December 2019.
At the same time, two weeks ago those same scientists hinted that because solar activity in the previous two months had exceeded their prediction, the next maximum would match the strength of the last maximum, weak though it was. Their official prediction, from April 2020 had however predicted a slightly weaker maximum in 2025, and the lack of activity in September suggests the April prediction might still hold.
It really is too early to say. For activity to fluctuate above and below the prediction from month to month is entirely normal. We will not get a full sense of the strength of the upcoming maximum until it is mostly passed and we can look back at it with some perspective.
We will also have to wait till then, sometime in 2026, to get some sense of that maximum’s effect on the Earth’s climate. Historically, the data suggests that low sunspot activity corresponds to a cooling of the global climate. The cause of this correlation is not yet understood, but the correlation appears to exist, nonetheless. Not only did the Little Ice Age in the 1600s correspond to the last grand minimum, when there were no sunspots for most of that century, the lack of any warming in the past twenty years matches the weak sunspot cycles over that same period.
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