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astronomy climate change Physics

Solar sunspot cycle 24 just ended

The 11-year sunspot cycle number 24 has just ended. We are entering sunspot cycle 25. The number of sunspots has been decreasing over the past 3 cycles which has been about 4 decades. See plot below.

Note cycles 20 to 22, with an increase in peak sunspot number, is the same period that global warming has been claimed to be most significant . Then from cycle 22 to cycle 24 we see a decrease, but also there have been reports of global cooling, most significantly in the last decade or so.

Here I have labelled the peaks with number assigned to each sunspot cycle. On the left vertical axis is the 13-month smoothed number of sunspots. This is equivalent to yearly average. Colours indicate the fact that north and south hemisphere exhibit different numbers of sunspots. Data are available here.