Feedback is central to the alarmist narrative on several levels. Negative feedback seven times more powerful for CO2 loss (from pre-industrial level, it is non-linear) than positive feedback for an equal gain is critical for the hypothesis that Milankovitch cycles explain why without exception temperature moves before CO2 in the ice cores. This may be why exceptionally powerful negative feedback parameters are built into the models.
Three hundred ninety-two point seven eight sounds like a lot of CO2 until you get to the parts per million, so let’s scale it back to something more humanly comprehensible: 39.28 per hundred thousand, 3.9 per ten thousand. Now we are getting to the scale of small towns and impressive gatherings.
Imagine ten thousand people marching up the Capital Mall. Imagine these to be all the atoms and molecules in the atmosphere. Four of them would be CO2. Ok, let’s round it up to 5 to account for the other “well mixed non-condensing” greenhouse gasses. It’s going to take some serious feedback for these five souls to control that crowd.
They do have disproportionate feedback. Water, the condensing and most powerful greenhouse gas is also found as a liquid and a solid in the atmosphere, but it is concentrated in the lower atmosphere. By mixing to high altitude CO2 is able to become a legitimate greenhouse agent, to the best of our follow the photon understanding of the greenhouse effect.
But there are only five of them in that crowd.
I was astonished so few reacted when Andrew Lacis posted the following on the NASA website in October 2010:
He did a model run with the non-condensing gasses entirely removed from a pre-industrial (only four at the march) level. The model responded with a global temperature drop of 4.6C the first year!
What an insult! Our collective human efforts since the industrial revolution digging carbon from the ground as well as prior and ongoing deforestation for fuel have been able to muster less than a 1 degree rise in global temperature according to the model. And this computer thinks it can take four guys out of a ten thousand man march and drop temperature that fast? Somebody, kick that thing!
Don’t believe anyone who says they know what global mean average temperature was during the glacial maxima. We really don’t know what it is today. But 4.6 degrees cooling is in the range of a glacial maximum. And it gets worse fast. In a decade the model would have more than 20 degrees cooling.
Try to imagine cooling at this rate in pre-industrial London. Within hours people would be running for shelter and lighting coal in their fireplaces. Within a month they would be ice skating on the Thames, even if it happened to be summer.
I think those feedbacks are way overfed.
geosciencebigpicture 
