kiwichick wrote:Hi Sparky.....thanks for your post.....and in words of one syllable ....what is the significance of quantifying the solar forcing.....apology's for my denseness...........
Not Sparky but will throw in my 2 cents. Solar forcing is the relationship between the number of sunspots and the total energy output by the surface of the sun that can be received by the Earth and other planets. A very active peak to the 11 year cycle makes the Earth slightly, and I do mean slightly, warmer than a low peak or the current nadir point.
With 400 ppmv CO2 plus other GHG in the atmosphere the variation in irradiance from the sunspot cycle becomes very much less significant than it was when we siting around 275 ppmv and went through the Maunder Minimum.
Some people blame the little Ice Age on the Maunder Minimum, the period when the sun had only a few spots at a time from 1645 to 1715 as seen in this graph tracking back to when Sunspots were first discovered. https://commons.wikimedia.org/wiki/File ... umbers.png
If you look at the spikes and swoops in the graph you might notice that over the top of the 11 year cycle everyone talks about there is also a 100 year cycle which you can see as a low sunspot number in the first full cycle after 1800 and again after 1900 and not surprisingly also in the most recent cycle after 2000. There are a number of scientists who support or disagree with the 100 year cycle and a large number of cycle lengths other than the 11 year short cycle have been proposed by various scientists over the years. It is even possible that there are several competing cycles that all line up around some longer number like 105 years or 2500 years.
If cycle 24 has actually ended early and Cycle 25 is about to start then the next 6 years will possibly lead to a much higher number at peak than the last 11 years did. The truth is scientists don't understand the physics well enough yet to predict with any accuracy how strong the next cycle will be. We could set an all new record high number or stay with a very low number for a decade or several decades, we can see evidence of both events occurring in the 406 years since sunspots were discovered in 1610.
Oh and from maximum to minimum the difference in solar output over the 11 year cycle is on the order of 1 Watt per square meter of the disc of the Earth. CO2 alone is providing a 1.9 Watt per meter square forcing 24/7/365 compared to pre industrial. On top of that the current Methane forcing is around 0.5 Watts m^2 and Nitrous Oxide is around 0.2 Watts m^2. With the forcing from just those top three man caused GHG changes we are talking about 2.6 Watts m^2 which totally swamps the 1 Watt m^2 effect of the solar cycle.
Solar cycles are interesting and worth learning about, but they are no longer considered by most climate scientists as a major driver of change unless the planet is right at a threshold value. The Little Ice Age caused very noticeable effects because the pre industrial GHG forcing levels were significantly lower than they are today. Then if you factor in the large volcanic events of the later 1700's and early 1800's the cooling effect had a large impact on crops in Europe and North America which caused crop failures that have been blamed in part for the French Revolution. Hungry people are liable to trow out whomever is in charge in hopes that the replacement will provide a better opportunity to survive.
I should be able to change a diaper, plan an invasion, butcher a hog, design a building, write, balance accounts, build a wall, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, pitch manure, program a computer, cook, fight efficiently, die gallantly. Specialization is for insects.