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by dahart 1042 days ago
It’s funny to focus on words that talk about “potentially” having an effect while ignoring the known magnitude of this potential. That quote taken out of context leaves you with the impression that these two factors are both significant contributors, or even roughly equivalent, but the reality is that one of those factors is much much larger than the other, and the other is negligible, and I’m sure you know which one is which.

“the Sun's energy output only changes by up to 0.15% over the course of the cycle, less than what would be needed to force the change in climate that we see. Also, scientists have not been able to find convincing evidence that the 11-yr cycle is mirrored in any aspects of the climate beyond the stratosphere – such as surface temperature, rainfall or wind patterns.“
1 comments
jpadkins 1042 days ago
what is the relationship between 0.15% more energy the sun may output vs. how much energy is retained via CO2 greenhouse effect?

https://earthobservatory.nasa.gov/features/EnergyBalance/pag... Indicates that 5-6% of solar energy is thermal radiation from the surface absorbed by the atmosphere (greenhouse effect).

This page states that CO2 is 20% of greenhouse effect https://earthobservatory.nasa.gov/features/CarbonCycle/page5... "Carbon dioxide causes about 20 percent of Earth’s greenhouse effect; water vapor accounts for about 50 percent; and clouds account for 25 percent."

So 1 to 1.2% of sun's energy is CO2 greenhouse effect. So a 10% change in CO2 greenhouse effect is roughly the same amount of energy as the observed change solar cycle output. tldr; 0.15% of sun's energy output is actually a lot of energy!

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dahart 1041 days ago
> a 10% change in CO2 greenhouse effect is roughly the same amount of energy as the observed change in solar cycle output.

I think your calculation might be mistaken, that number doesn’t make a lot of sense and is not supported by measurements. See Figs 13 & 16 in the following paper for magnitudes of temperature variation attributed to solar cycle variation.

https://www.imperial.ac.uk/media/imperial-college/grantham-i...

The link you provided summarized the solar cycle’s contribution to warming as “very small”. This paper also notes that the solar cycle’s affect in the last 50 years has been cooling on average, and that recent warming trends are “almost entirely” due to changes in CO2.

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