NOAA today released its monthly update of the Sun’s sunspot cycle, covering the period of May 2013. As I have done every month for the past three years, I have posted this latest graph, with annotations to give it context, below the fold.
For the third month in a row, the Sun has shown increased sunspot activity. Though the total activity continues to remain well below all predictions, it appears that the Sun is going to produce a double-peaked maximum, as predicted by some solar scientists back in March. Be aware however that this prediction isn’t based on any real understanding of the physical processes that produce sunspots but is instead based on the fact that the Sun has sometimes done this in the past. If you asked these scientists why the Sun sometimes produces a double-peaked maximum they will wave their arms about but will really not be able to tell you.
I have once again added the predictions of the solar science community to give the graph context. The green curves in the graph show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction.
This string of active months has also prompted the solar scientists at the Marshall Space Flight center to once again revise their prediction for the solar maximum. Instead of a sunspot maximum number 66 coming in the fall of 2013, they now claim the maximum number will be 67 and will occur during the summer. As they make changes like this routinely, this newest “prediction” is not really worth the electrons they used to send it out over the internet, especially coming as it does mere months from maximum.
I suspect we might get another strong month of activity in June, but the data continue to suggest that Sun’s maximum will be over by sometime this fall, when we will begin to see a steady ramp down in the number of sunspots.
It is then that we will await the answer to what is the big scientific question in the solar science community: Will the Sun then enter a prolonged Grand Minimum, with no sunspots for decades and similar to the Maunder Minimum of the 1600s, or will the eleven-year solar cycle continue as it has for the past three hundred or so years?
The answer to that question is crucial, for two reasons. First, a Grand Minimum now, with our modern space-based technology, will give scientists an opportunity to study the Sun — as it behaves in a relatively unusual manner — at a resolution never before available. With such good data, they might actually figure out the solar dynamo that produces sunspots, a process that they presently really do yet not understand.
Second, and more important, a Grand Minimum now would help climate scientists figure out how important the Sun is to climate change. Most climate scientists dismiss the Sun’s solar cycle, considering the changes during its eleven year cycle too small to influence the climate. A Grand Minimum, however, might change those opinions significantly.
Moreover, though the Maunder Minimum in the 1600s coincided with the Little Ice Age, our data on the Sun’s brightness during that time period is simply not good enough to tell us if it was the minimum that caused the lower global temperatures. Another minimum now would help answer that question.
Knowing these facts, with good robust data, is essential if we are to get a true and unbiased understanding of the Earth’s climate.