The climate system certainly has positive feedbacks, and it certainly has negative feedbacks. We are talking about an enormously complicated system and a wide range of time scales. Furthermore, there are a variety of forcing functions, from CO2 changes to Solar insolation changes to stratospheric particulates to biologically induced major ecological shifts (plant parasites, for example).

CS’s point is that the climate is unlikely to be dominated by a positive feedback over a wide range of temperatures. Even if there is a >1 alpha at some point, the system is so nonlinear that this will change with temperature (and CO2, and water vapor, and sunlight, and cow flatulence, and…). Something is acting as an overall regulator because the temperature fluctuations have limits. I wouldn’t be surprised if the overall very long term trend is positive due to normal long term solar star aging. But the earth has tolerated a lot of very strong climate forcing, most of them without catastrophic effects on life. CO2, in comparison, is a weak forcing. Furthermore, if we characterize the nonlinearity of gravitational force on a falling ball as positive feedback, then the forcing function of CO2 clearly has negative feedback – the GW effect of CO2 (ignoring all other factors) is logarithmic with increases. Twice as much CO2 doesn’t give you twice as much warming – even in a lab.

A pendulum is one simple example. The mean is the rest state of straight down. The weights or springs of the clock add energy, and the pendulum dampens the swings produced due to the negative feedback that pulls the pendulum to the center more strongly as it is perturbed further away from center.

The climate oscillates (though not between two “states”) in a much more complicated manner, but essentially the same way. The sun, and the internal heat of the earth add energy, and the various negative feedbacks pull the climate back toward a mean, more strongly the further it gets perturbed, and then past that mean to an opposite extreme, from which it is again pulled back.

The last, best hope for catastrophic AGW/CC is that there is a local maxima nearby on the solution space of possible climate states that we could push the climate over, analogous to pushing the pendulum so hard that it spins all the way around, or breaks off the clock completely. If that were the case, the climate could be pushed into either a different equilibrium around a different local minima, or into a regime of positive feedback.

It’s possible, but very unlikely, as the climate has tested those boundaries numerous times in the past and always returned. Still, if that’s what you watermelons want to argue – and it’s the absolute last even remotely plausible argument you have left – you’ll have to start working on identifying where that nearby ridge is, what it would take to get over it, and what it will take to prevent it. You’re nowhere near even starting on that – you won’t even admit that we are in a long term stable regime dominated by negative feedback.

“(Me:) “The actual climate record is more gradual – the whip does not suddenly “crack” ” (PS:)another wonderful slice of ignorance. Frequently throughout Earth’s history, the climate has changed quickly enough to trigger mass extinctions.”

Way to go PseudoScientist. Pull a quote out of context and call it ignorant. My comment was with regards to an actual whip, and the suddenness with which it is pulled back by a countervailing force added all at once. The climate does not behave in that manner, though the interaction of various negative feedbacks can make it look like it does.

Fair enough. I can see how you might read it that way, although the apostrophe is in the wrong place for that interpretation.

Jens, in common sense, you are “right”, but rigorously speaking you are not. Gravity theory implies that the earth exerts the exact same force on the rock as the rock on the earth. The problem is that F=ma, so for a given F, the small mass of the rock implies a much, much higher acceleration compared to the earth’s, which has an enormous mass. So acceleration does depend on the masses involved. The force that the black hole you mentioned on the rock is exactly the same force that the rock exerts on the black hole! It may seem counter intuitive, but that’s how it works. And science trumps feelings.

If you put two marbles (A and B) a meter apart, nothing much happens, right?
If you put a marble (A) and a black hole(B) a meter apart, something DOES happen, right?

The solution is that the TRUE acceleration between the two objects has TWO components. The acceleration A exerts on B was proved independent of B’s mass – but the acceleration B exerts on A is VERY dependent on B’s mass.

In the rock vs. earth case, the rock is accelerated by the earth the same no matter how heavy it is – but it’s got to be one hell of a rock for you to notice how much the rock accelerates the earth!

As the snowball accumulates mass, the force on it increases, but the acceleration stays the same. Uniform gravity puts F = mg so as the mass increases, so does the force. But F = ma as well, so mg = ma and g = a. The acceleration due to gravity is constant. (To the level of accuracy we’re considering things.)

There is another effect to consider, and that is that the snowball is rolling. Energy is going into rotational motion too. This slows the acceleration down, but for rolling spheres or cylinders things cancel out again and the acceleration is constant. In general, the acceleration is g sin(theta)/(1+I/Mr^2) where theta is the hill’s slope, M the mass, r the radius of the ball/cylinder, and I the moment of inertia. Since the moments of inertia for sphere (2/5)Mr^2 and cylinder (1/2)Mr^2 are both proportional to Mr^2, the change in mass and radius cancels out, and the acceleration is constant.

“This is a hobby article, not a peer-reviewed paper.”

Good point. And since this blog is not a peer-reviewed paper either, will you grant it the same latitude and call for people to leave its technical shortcomings uncommented on? And comment similarly on the maturity of those who do so?

It’s an educational presentation on global warming, the most important issue of our age according to some, and when sceptics cast doubt by means of such using scientifically dodgy material, that’s an outrage that ought to be banned by law they say. But when people speaking for it get basic science wrong, it suddenly isn’t. What does that tell you?

Right here.

Clearly, we haven’t warmed that much.

Therefore, it is a cherry-picked graph.