In the two prior postings Sun and Climate,Parts 1 and 2,  we have talked about Solar Activity and how it relates to climate.  In Part 1, the discussion was primarily about Solar Insolation, and Part 2 began the discussion about solar activity using Sunspots as a proxy.   Sunspots are popularly used to indicate Solar activity due to their longevity.  Galileo began noting and recording them in the sixteen hundreds.

Ok,   now lets look at some more physical evidence that shows a strong correlation with solar activity/climate change.

Two much newer and probably better proxy measures are Solar Flux and Average Magnetic Planetary Index (Ap index).


The former is a measure of noise or flux that is emitted at a frequency of 2800 MHz (10.7cm).  This measure is typically referred to as F10.7.  This proxy measures ionization in the ionosphere’s F region.    The solar wind from the Sun contains many atomic particles.  The Earth’s geomagnetic field deflects the majority of the protons and electrons being expelled from the Sun toward the Earth.  But the as the Sun’s activity increases more particles are expelled and more break through into the Earth’s ionosphere where F10.7 measures the increase.    Continuous F10.7 measurement and record maintenance began in 1947. As can be noted from the shape of the current (Nov. 2010) monthly summary chart of F10.7,   it is lagging the same point on the red line where the experts had predicted it would be at this time in Cycle 24.

And as we noted in Sun and Climate Part 2,  the forecast Cycle 24  has been  scaled down several times in the last few years in order to match actual real world results which have consistently come in below each new forecast.  Note that the level of F10.7  at the peak of Cycle 23 in 2001 and 2002 reached nearly 240.


The Sun’s magnetic field extends far out into space.  It not only surrounds Earth, it also extends well beyond Pluto.  The more powerful the Sun’s magnetic field, the more it alters the  Earth’s geomagnetic field.    The Ap index is measure of this alteration.   The Ap index measurements began in the 1930’s.   The chart  that follows shows the Ap index beginning in 2000 through most of  2010.  The peak in the 2003 -2004 time frame is Cycle 23.  The Solar activity was high during that time, reaching an Ap index of 35 at its peak.  In October 2005,  the Ap Index dropped significantly and has remained very low since then.

The  following chart shows the Ap index from October 2010  through the end of December 2010.  Note that the index has bottomed out at zero on several occasions.  This chart also illustrates the how well the Solar Flux, the Sunspot Number and the Ap Index  correlate.

(This chart was prepared by Jan Alvestad)

No one knows exactly the mechanism that causes the Earth to cool when these proxies are low or warm when they are up.  No one knows exactly why the Sun has 11 (+-) year cycles.  Maybe we will never learn enough to be able to predict accurately the future state of the solar activity.  If so,  we will never be able to accurately predict the Earth’s future climate.  But we can reasonably predict that the Earth’s climate will cool as long as these proxies stay low (below normal), indicating low solar activity.
Moreover, we can’t control solar activity.  We can’t control Earth’s orbit around the Sun.  The Sun is in charge of our climate.  Man has precious little control of the climate in the big picture.   Attempts to moderate the Earth’s climate through reduction of CO2, for example, will have limited to no effect on climate although it will have a profound negative impact on our economic well being .

Our efforts should be directed toward adaptation to what every the Sun dishes out.

For more on this topic see posting Part 1 and Part 2 of Sun And Climate.



  1. Pingback: Solar Cycle 24 Nearing Maximum | Climate Change Sanity

  2. Pingback: Solar Cycle 24 Nearing Maximum | Climate Change Sanity

  3. Pingback: Svensmark Theory—Cosmic Rays Contribute To Lower Global Temperatures | Climate Change Sanity

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