F10.7 Flux, Sea Level and the Holocene

Guest post by David Archibald

George Orwell said,” He who controls the present, controls the past. He who controls the past, controls the future.” Some amongst us have used that as an instruction manual and have attempted to create confusion about the sunspot number record. We can sidestep all that by using the F10.7 flux which can’t be fiddled with and adjusted. The F10.7 instrument record goes back to 1948:

It has been previously derived that the break-over between sea level rising and falling is a sunspot number of 40: http://wattsupwiththat.com/2012/02/03/quantifying-sea-level-fall/ A sunspot number of 40 equates to a F10.7 flux of 100.

WUWT recently alerted us to the existence of Usoskin’s 2010 paper on solar activity during the Holocene, available here: A History of Solar Activity over Millennia

Usoskin’s paper contains a lot of useful information that allows us to backtest the relationship between solar activity and sea level. For example, consider that if the average sunspot number over the Holocene had been above or below 40 over the Holocene, then sea level would have risen or fallen over the Holocene according to my theory. His Figure 18 provides the answer:

Figure 18 shows that the average sunspot number over the Holocene was very near 40. We can also tie sea level events over the Holocene to the detail in Usoskin’s Figure 17:

The figure above is the last six thousand years of sunspot number. It is evident the average sunspot number was higher prior to 0 BC and lower since. Sea level therefore should have been higher prior to 0 BC and lower since. That is confirmed by a 2007 paper on Holocene sea level variability: http://www-public.jcu.edu.au/public/groups/everyone/documents/journal_article/jcuprd_054910.pdf

From the abstract,”the Holocene sea-level highstand of +1.0 – 1.5 m was reached ~ 7000 cal yr BP and fell to its present position after 2000 yr BP.” Low sunspot periods from Usoskin’s Figure 17 are evident in the sea level record. Further from that abstract,”During this ~ 5000 year period of high sea level, growth hiatuses in oyster beds and tubeworms and lower elevations of microatolls are interpreted to represent short-lived oscillations in sea-level of up to 1 m during two intervals, beginning c.4800 and 3000 cal yr BP. The rates of sea-level rise and fall (1-2 mm yr) during these centennial scale oscillations are comparable with current rates of sea-level rise.” On Usoskin’s Figure 17, the 4,800 BP date corresponds to the low sunspot period at 2,800 BC and the 3,000 BP date corresponds to the low sunspot period at 800 BC.

The Usoskin paper contains another instructive figure, his Figure 13 of an example of a reconstruction of the heliospheric magnetic field at Earth orbit for the last 600 years:

The benign period of the second half of the 20^th Century is associated with a far more active Sun. The cold periods are associated with a heliospheric magnetic field of under 2 nT. How does that compare with the modern instrument record? The following figure shows that the recent range of the magnetic field equates to that of the first half of the 20^th Century:

Now back to the F10.7 flux and sea level. Based on the length of Solar Cycle 24 derived from Altrock’s green corona emissions diagram and Livingston and Penn’s prediction of peak Solar Cycle 25 sunspot amplitude of 7, we can predict the general form of the F10.7 flux to 2040:

I have come to the conclusion that a F10.7 Flux of 100 is the breakover between heating and cooling on Earth. It explains most things to me. My best guess on that at this point is January 2015, following which, two decades of cooling will ensue.