A cluster of low sunspot cycles could be a factor ending the current interglacial

The 24th Solar Sunspot Cycle since 1755 is coming to an end. These cycles are nominally of 11 years and this cycle started in December 2008. While the Sun is spotless today, trough conditions will likely extend into at least next year. The designated “start” of Cycle 25 will not be determined for a few years yet but is likely to be in 2020 or 2021.

Dr. David Hathaway retired from NASA’s Ames Research Center in 2016 but now runs a Solar site of his own. He writes

Solar Cycle 25 Prediction. We find that the polar fields indicate that Cycle 25 will be similar in size to (or slightly smaller than) the current small cycle, Cycle 24. Small cycles, like Cycle 24, start late and leave behind long cycles with deep extended minima. Therefore, we expect a similar deep, extended minimum for the Cycle 24/25 minimum in 2020.

Hathaway – cycle 25 prediction

Actual sunspot numbers for cycle 24 are shown here

Cycle 24 actual

Cycles 24 and 25 will show very low values. Whether something similar to the Maunder Minimum actually results remains to be seen. Nevertheless, sunspot number values are going to be low till at least 2033 when Cycle 26 enters its growth phase. If Cycle 26 also turns out to be a low sunspot number cycle, it may well portend not just a little ice age but even be an indicator that this interglacial period is coming to an end.

We don’t know what triggers the change of conditions to and from an interglacial. The transition time is likely at least a few decades and more probably a few hundred years. There are probably many “triggers” needed simultaneously to end an interglacial, but a a few very low sunspot cycles clustered together could well be one of the important ingredients. The current interglacial has lasted longer than usual. A glacial period within the next 1,000 years is almost a certainty.



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