Hello Ken G. in reply to your comment.
Are you interested in solar atmosphere physics or paleoclimatology?
1) How could solar magnetic field changes affect planetary temperature?
The solar magnetic field changes are hypothesized to affect planetary temperature by modulating planetary cloud. (More clouds, cooler planet and less clouds, warmer planet.) Satellite observations by Palle and observation of changes of the earth’s albedo by observing earthshine reflected off of the moon also by Palle, supports the hypothesis.
There are two mechanisms in which solar magnetic field changes could modulate planetary cloud cover.
The effect of cloud modulation is greatest over the oceans where there is less dust to form clouds and there is a shortage of cloud forming ions. (Rain removes the ions, so they must be replenished.) As the oceans act as a heat sink and the area of ocean cloud cover is large, a long term change in low level clouds over the ocean has a significant effect on planetary temperature.
The following are the two cloud modulating mechanisms:
1) "Electroscavenging" which is the name for the mechanism where sudden solar wind bursts are hypothesized to increase currents in the ionosphere which remove cloud forming ions.
2) Modulation of Galactic Cosmic Rays (GCR) by changes in the solar heliosphere. Svensmark has done some detailed research in this area. The high speed GCR (mostly protons) strike the earth’s upper atmosphere and create muons. The muons travel on to lower regions of the atmosphere where they create cloud forming ions. (More GCR more clouds and less GCR less clouds.)
This is Palle’s satellite paper.
“The possible connection between ionization in the atmosphere by cosmic rays and low level clouds” by Palle et al.
http://www.arm.ac.uk/preprints/433.pdf
Quote:
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As evidence for a cloud—cosmic ray connection has emerged, interest has risen in the various physical mechanisms whereby ionization by cosmic rays could influence cloud formation. In parallel with the analysis of observational data by Svensmark and Friis-Christensen (1997), Marsh and Svensmark (2000) and Palle´ and Butler (2000), others, including Tinsley (1996), Yu (2002) and Bazilevskaya et al. (2000), have developed the physical understanding of how ionization by cosmic rays may influence the formation of clouds.
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In addition to relatively short term modulation of Galactic Cosmic Rays due to changes in the solar heliosphere, there are astronomical reasons for long term changes in GCR magnitude.
The Israel physicist Shaviv has shown that the magnitude of GCR changes depending on the position of the solar system in the Milky Way. When the solar system passes through the galactic arms there is an increase in GCR. Shaviv has presented data that shows there is an increase in GCR (the increase in GCR causes isotope changes in asteroid fragments. Shaviv studied meteoroids. See paper below for details.) and that the periods of increased GCR, correlate with ice epochs, including the current ice epoch.
“Celestial driver of Phanerozoic climate?’ By Nirva Shaviv & Ján Veizer
http://www.phys.huji.ac.il/~shaviv/I...s/GSAToday.pdf
In response to your question: What is the relative magnitude of solar and GCR cloud modulation Vs other climate forcing functions, the following paper also by Shaviv estimates the different forcing function.
“On climate response to changes in the cosmic ray flux and radiative budget” by Nirva Shaviv.
http://arxiv.org/PS_cache/physics/pd.../0409123v1.pdf
This paper by Shiva provides an explanation for the early faint sun paradox.
Towards a Solution to the Early Faint Sun Paradox: A Lower Cosmic Ray Flux from a stronger Solar Wind
http://arxiv.org/PS_cache/astro-ph/p.../0306477v2.pdf