Anomalism
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- Dec 1, 2020
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- #481
“In the absence of climate feedbacks, a doubling of CO2 would cause a global surface warming of about 1.0–1.2C. Including fast feedbacks increases this warming to about 3 C.” - AR6 WGI, FAQ 7.1Show me the split or comparison of direct to feedback. Don't provide links that I have to search for it. Quote it verbatim.
“The best estimate for equilibrium climate sensitivity (ECS) is 3.0 °C… ECS includes the combined effect of fast feedbacks (water vapor, lapse rate, surface albedo, clouds) that amplify the direct radiative forcing.” - AR6 WGI, Ch. 7, Section 7.5
AR4 SYR Section 2.3 also notes: “Climate sensitivity of about 3 °C implies that feedbacks roughly double the warming response relative to the direct radiative forcing alone.”
So the numbers break down like this:
Direct CO2 effect: ~1.0–1.2C
Feedback amplification: ~1.8–2.0C
Total ECS: ~3C
These are not hidden or assumed. They are explicitly quantified in the IPCC reports. The feedbacks are measurable, constrained by observations, and fully incorporated into detection and attribution studies. The direct forcing alone does not account for observed warming; the total warming arises from direct CO2 plus these well-characterized feedbacks.