Posted by: Grant | January 31, 2012

Got The Feedbacks WRONG

Dr David Evans posts On Jo Nova on what went wrong with the UN IPCC models.

JO NOVA BLOG
Dr David Evans: The Skeptic’s Case
http://joannenova.com.au/2012/01/dr-david-evans-the-skeptics-case/#more-19931

“The serious skeptical scientists have always agreed with the government climate scientists about the direct effect of CO2. The argument is entirely about the feedbacks.”

” …Figure 2: The skeptic’s view. If the CO2 level doubles, skeptics estimates that the temperature increase due to that extra CO2 will be about 1.1°C × 0.5 ≈ 0.6°C.[4]  

The serious skeptical scientists have always agreed with the government climate scientists about the direct effect of CO2. The argument is entirely about the feedbacks. The feedbacks dampen or reduce the direct effect of the extra CO2, cutting it roughly in half.[5] The main feedbacks involve evaporation, water vapor, and clouds. In particular, water vapor condenses into clouds, so extra water vapor due to the direct warming effect of extra CO2 will cause extra clouds, which reflect sunlight back out to space and cool the earth, thereby reducing the overall warming.  

There are literally thousands of feedbacks, each of which either reinforces or opposes the direct warming effect of the extra CO2. Almost every long-lived system is governed by net feedback that dampens its response to a perturbation.
If a system instead reacts to a perturbation by amplifying it, the system is likely to reach a tipping point and become unstable (like the electronic squeal that erupts when a microphone gets too close to its speakers).
The earth’s climate is long-lived and stable— it has never gone into runaway greenhouse, unlike Venus — which strongly suggests that the feedbacks dampen temperature perturbations such as that from extra CO2…. “

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