Must be careful with this statement. Changes in ground area vs sea area under effective insolation ('Solar Irradiance') due to continental drift is why we are currently in an Ice Age.
Antarctica moved to the south pole: all that quick-heating land vs slow-heating sea moved to a place with low insolation - and the world became way colder.
The Cosmic Ray theory (now proved!) affects climate on the order of 11 year Solar magnetic cycles, and multiples of 11 yr cycles.
The sun in general is (of course!) the driver of climate and therefore of climate change, but the cosmic ray variation is a small part of it.
“effective insolation”
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You’re talking variation in absorption, not irradiance.
I get your point though and agree with it.
” but the cosmic ray variation is a small part of it.”
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Variation in the total amount of cosmic rays penetrating the Earth’s atmosphere and nucleating cloud cover is turning out to be the main driver of so-called climate change, if you ask Professor Svensmark.
Effective insolation as used in most calculations only uses solar light and totally ignores solar wind, high energy particles, coronal mass ejections, x-rays, magnetic field effects, etc.