It is the first of the month, and NOAA has once again updated its monthly graph showing the long term trends in the Sun’s sunspot activity. As I do every month, I post it below, annotated with additional data to provide some context.

In March the Sun continued its unexpected high activity since the end of the solar minimum in 2020. The number of sunspots once again rose steeply, while also exceeding the predicted count for the month. The actual sunspot count for March was 78.5, not 34.1 as predicted. The last time the count was that high for any month was September 2015, when the Sun was just beginning its ramp down from solar maximum.

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 very steady and very steep rise in sunspot activity since 2020 strongly suggests the next maximum will not only occur early, but will be much higher than the 2020 prediction of NOAA’s panel of solar scientists. This pattern also continues to suggest that the outlier prediction of a handful of solar scientists that this maximum will be a very strong one will be the correct one.

Not that this successful prediction would count for much. Both predictions were merely based on the past cyclical but superficial behavior of the Sun. Neither was based on an actual understanding of the fundamental processes that cause sunspots or these cycles. At the moment, scientists really do not know why the Sun’s magnetic field flips its polarity every eleven years, causing a rise and fall of sunspot activity as it does so. All they really know is that the Sun’s magnetic dynamo and field cause the spots.

Nor do scientists yet know if these cycles influence the Earth’s climate. Circumstantial evidence strongly suggests that they do. When the Sun is inactive, the Earth’s global temperature appears to cool. When the Sun is active, that global temperature appears to rise. How the two are linked however is not really understood. Though the Sun varies in total radiance in lock step with the sunspot cycle, the variation in optical wavelengthes doesn’t appear to be enough to matter. How much it varies in other wavelengthes is not yet fully known, and even in optical there is great uncertainty. Furthermore, there are other factors, such as cosmic rays, that vary in lock step as well, and could impact the Earth’s climate also.

The 2011 presentation below by scientist Jasper Kirkby is still entirely relevant, and provides a very complete and accurate summary of this science. It also outlines one proposed theory for explaining the link between the sunspot cycle and climate.