On Climate Audit’s unthreaded comment forum, David Archibald noted some interesting facts about the solar cycle lengths and upcoming Solar Cycle 24, and provided the graph above.
Solar Cycle 20 was slightly longer than average at 11.6 years. The average solar cycle length from 1643 to 1996 is 11.4 years. Now that Dr Svalgaard has mentioned it, let’s talk about Solar Cycle 21. It was short at 10.3 years and hot (it started at the same time as the PDO shift in 1976) and was followed by a solar cycle 22 which was shorter again at 9.6 years and hotter. According to Friis-Christensen and Lassen theory, Solar Cycle 23 should have been hotter than Solar Cycle 22, and it was, even thought it is going to be a long one at about 13 years. There is plenty of correlation, all in our lifetimes. As for the physics, Hathaway found a correlation between Solar Cycle Length and the amplitude of the following cycle.
As for Solar Cycle 23 being almost done with, those are comforting words but the observational data suggests otherwise. Jan Janssens does it best – a recent plot is above. That suggests that we have a year to go and that Solar Cycle 23 is likely to be 13 years long. This is 3.4 years longer than Solar Cycle 22 and thus with mid-latitude temperatures responding at the rate of 0.7 degrees C per year of solar cycle length, Solar Cycle 24 will be 2.4 degrees cooler than the one we are still in.
The Financial Post has a story (Our Quiet Sun) that is echoing much of what Archibald is saying, but is quoting from other sources:
The sun, of late, is remarkably free of eruptions: It has lost its spots. By this point in the solar cycle, sunspots would ordinarily have been present in goodly numbers. Today’s spotlessness — what alarms Dr. Chapman and others — may be an anomaly of some kind, and the sun may soon revert to form. But if it doesn’t – and with each passing day, the speculation in the scientific community grows that it will not – we could be entering a new epoch that few would welcome.
Joe D’Aleo did an essay on IntelliCast on the possible consequences of a Solar Cycle 23 running out to 13 years, using some of the same things Archibald is saying:
Looking back at the full record of sunspot cycles, we can see this general behavior of short active cycles and longer, quiet ones. Successive 11 year cycles are different in their magnetic fields and the 22 year Hale cycle has in the past been related to some phenomena such as drought. Longer term cycles are apparent when you carefully examine the data. Very obvious from the long term plot of the 11 year cycles is the approximate 100 (106) year cycle. There is also a 213 year cycle. The last 213 minimum was in the early 1800s. The turn of each of the last 3 centuries has started with quiet long cycles with mid-century shorter, higher amplitude cycles. The quietest period was in the early 1800s (the Dalton Minimum). The 100 and 200 year minima are due the next decade suggesting a quieter sun ahead.
I’ll take Global Warming any day of the week and twice on Sundays over a Little Ice Age.