Feedback in the traditional electrical engineering sense is when a system takes some of the output and puts it back into the input. This can be done negatively and positively. Negative feedback is almost wholly beneficial and occurs in nature, because it has a stabilising effect. As the input for our ecosystem is almost exclusively the sun it's difficult to see how feedback works in climate science what I think they mean is that heat is retained while the input that caused it continues so it gets hotter. I have little doubt that water vapour retains heat, I said on one of your threads before, if you go into the desert where there's carbon dioxide as soon as the input (the sun) goes down you can get a 30C change in temperature. On a beach in Thailand the temperature barely drops, while in Hong Kong, very humid, it sometimes doesn't drop at all. So humidity holds heat. Having said that, the next morning when the sun starts shining again the temperatures don't double, so there's something going on which isn't the understood feedback mechanisms of the electronic engineering world.

Martin, you say that, "...that the climate has never... gone into large oscillations for no obvious reason". How do you know that exactly? Is there some proxy reconstruction that you believe in sufficiently to prove that? Or (heaven forbid) a model?

Don Keiller's graph of temperature, which I haven't noticed you disputing, purports to show bistable behaviour. That sort of implies tipping points, don't you think?

"However, the fact that the climate has never

- whacked over to one side, hit the stops and stayed permanently there

- gone into large oscillations for no obvious reason

seems pretty conclusive evidence that if there is any positive feedback, it is not strong in its effects. Plus "tipping points" don't seem to come into the picture."

Agreed MartinA, there is no historical evidence for tipping points, or even for a sensitivity of 3. I tried to make this point to Richard Betts the other day asking why we'd never seen the sensitivity show up in the past when temperatures reached 1C, the supposed tipping point.

Another thing that puzzles me is that the Earth is unaware where the heat comes from i.e. if it warms and it has a sensitivity of some sort, maybe not 3, then there should be positive feedbacks associated with the warmth. So are we looking at a temperature rise of 0.75C caused entirely by CO2 or are we looking at a temperature rise of. say 0.375C with a sensitivty of 2 bringing it up to 0.75. And why then doesn't it spiral out of control like any other uncontrolled positive feedback?

As you say typically feedback occurs when some of the output is fed back into the input. With the climate that's not happening, all that happens is that some of the heat is retained in the system, but as I pointed out before in warm wet climates, in the tropics, the overnight temperature barely drops, but when the Sun comes up it doesn't rise dramatically, begging the question why the sun doesn't simply add heat to what's already there and giving huge rises in temperature. In dry areas, deserts etc; it's brass monkey's cold at night and goes into the 30s during the day in the summer. The conclsion is that somehow or other the water vapour, far from acting as a positive feedack (in the climate science sense of the word) is actually keeping the temperatures fairly constant.

So we so have presence and absence of water vapour to observe, and the higher the water vapour the closer the night and day temperatures. I'm sure someone can provide an explanation for this, but it's not positive feedback.

Rhoda, you almost certainly would find evidence of "positive feedback" in the biological and engineering sense of the word. However, like all thing climate science they have appeared to use the word "feedback" to illustrate something, which in my view at least, isn't feedback at all. It's heat retention and rejection at the speed of light, or nearly anyway. As with all things in the non-debate the climate scientists aren't having with anyone we appear to have accepted the word feedback so we can move on. MartinA will, I hope, agree with me that if you have a system with positive feedback it is likely to self destruct unless you can introduce damping factors. Clearly there are no signs in the records of widespread destruction caused by high temperatures, and given the tool human ancestors had to deal with changes in their environment it is highly likely we wouldn't be here now. The rule of thumb is that positive feedback systems are inherently unstable, while negative feedback system are stable.

I don't believe you can do an experiment in the lab because there are too many parameters that interact together in complex ways and we would be unable to replicate that in the lab. Not least because there are clearly unknown parameters reacting with all the known parameter in non-linear fashion.

I also don't believe the feedback, if that's what it is, is positive, it is an artifact of the modellers' imaginations.

Martin, I do not lack goodwill towards you or Rhoda and I have no reason to doubt my comprehension skills.

Why the sensitivity? If the climate can behave in a bistable manner (for which there may or may not be evidence - but some sceptics seems to believe) that implies tipping points, like the Schmitt triggers you and I once used. The conventional meaning of 'never' is not, "not in the time-frame that I feel comfortable talking about", but 'not ever'. I see no evidence that Rhoda was asking about feedback only in modern times...

Like Don Keiller, you seem to want to make unequivocal statements, are then reluctant to provide proof and get upset when challenged. What is so difficult about it? Have there ever been large oscillations or not? And where is your proof. It is okay to say, "I don't really know". You would expect no less from a warmist making such assertions than I am asking of you.

Here's the difference for me. In electronic series the feedback is always controlled by an attenuator, in the feedback loop, so that the feedback is controlled to provided the desired response at the output.

Now climate science theory:

1. Extra CO2 in the atmosphere causes an increase in temperature (based on the physical hypothesis and the 1980 tt 2000 correlation, nowhere else has this relationship been established);
2. The temperature rise causes a rise in temperature in the oceans increasing the water vapour AND the CO2 in the atmosphere (centuries after the rise in water vapour as I understand it);
3. The increased water vapour increases the temperature;
4. This in turn increases the temperature which releases more water vapour AND CO2 into the atmosphere;
5. The increased water vapour increases the temperature.
6. It's now can't stop if the sun keeps pumping 350 watts/M^2 into the Earth.

By that logic we could not have passed any point in history where the world started warming without experiencing catastrophic global warming. So what has stopped this happening now, and in the past? There has to be something in the natural cycles that keep the warming from running out of control, be it the Oceans, the Orbital path, gamma rays from outer space or, most likely of all, the clouds that form with the extra water vapour. It's a lot more complicated than the climate scientists seem to think, the biosphere. At least to me.

Martin, I think you are wrong. Scientists love their children too. I imagine most would be delighted to find that there is no positive feedback.

@BitBucket "Scientists love their children too. I imagine most would be delighted to find that there is no positive feedback". Activists love their children too. I imagine most would be appalled to find that there is no positive feedback. So, who is scientist, who activist? Hard to tell, eh?

@BitBucket "Scientists love their children too. I imagine most would be delighted to find that there is no positive feedback". Activists love their children too. I imagine most would be appalled to find that there is no positive feedback. So, who is scientist, who activist? Hard to tell, eh?

I respect science absolutely. I am in awe of the insights of Copernicus, Galileo, Newton, Maxwell and Bohr/Einstein. But their legacy deserves better than the current pretence of "climatologists" who it seems have no useful additional new insights whatsoever. Nevertheless, they are well on the way to wrecking our civilisation by managing to demonise Carbon, yes you heard correctly, Carbon. Carbon? It's what all living things are made of. What on earth are we signing up to?

Rhoda, flattering though it might be, I don't think the world's scientists are collectively saying, "its okay, BitBucket's got that covered on the Hill". I imagine the answer is that they don't know. That's okay too. We'd all like certainty, but maybe there isn't any.

Simon, why should activists or activist scientists be appalled? Do you think they get worked up about AGW for some ulterior motive or because they are worried about it? The latter seems most likely. I'd imagine they too would welcome a lack of feedback. As for wrecking civilization, do you think that a society organized around non-carbon-based fuels cannot still be civilized?