Dim Sun Anyone?

[MSimon]

Simon -

After the last link I don't have to post more dirt on Lindzen? Whether or not you share his politics, it is established that whatever he says about sience is unreliable?

Let me know if you want a sustained Lindzen slur campaign here.

However in your post I see you have now abandoned the "AGW is not happenning" argument and moved on to the "corrupt governmental processes mitigating CO2 emmissions will do more harm then good" argument.

Logically, to think clearly about this issue. we need first to evaluate what benefit (or loss of harm) to the world, or to your local kin-group - since you perhaps would find this more relevant - continued unrestrained CO2 emmissions will do.

The IPCC has done a good job of quantifying this and stating the uncertainties.

Once we have some agreement on that we could consider what actions (whether it is working on a new Polywell or cap & trade limits) will actually help.

My problem with your position is that you conflete the two - and spend half your time (incorrectly) rubbishing science you have not bothered to look at with due care - assuming that your favourite politically sympathetic blog comment is authoritative. Just as ravingdave earlier on this thread.

As polemic - to convince the unthinking masses - this sort of subject switch works well. Not here, I hope?

Best wishes, Tom

Tom,

All I will say about AGW is that if it is happening it is insignificant.

Yeah. Keep slurring Lindzen with links from Real Climate. And Jim Hansen did consulting for Enron and when he was there he said AGW was probably not happening. Enron was looking for a way to get carbon trading going which is why they hired him. Evidently Hansen saw the money and changed his mind.

And yeah. I'm totally ignorant of the science. Lucky for me heh? I can just spout nonsense. Like asking why it took so long to incorporate the PDO and other ocean currents into the models. And why I have yet to see any papers that deal with the possible aliasing of the PDO (and other ocean current) warming for CO2. And how the models could achieve the claimed accuracy when modeling a chaotic system whose variables are not well understood with a model so coarse that it can't tell mountains from the seashore. And in which many of the parameters used are just WAGS. Or how the models can predict to .2 deg F when the temperature record they depend on is only reported to 1 deg F. With an error bar on top of that of +/- 2 deg F making the error bar of the individual measurements +/- 3 deg F. Or worse depending on the calibrations of the glass thermometers. Or how moving a thermometer in a Stevenson shelter a few inches can change the reading by another deg or two F. And how the shelters are not all a uniform height - there is another deg or 3 F. Or how variations in plant cover over decades adds another +/- 3 F to the error bars. Or how unaccounted station moves ands more error. And out of this mass of error climate models can come up with imputed accuracies of +/- .2 deg F. And did I mention that that is for the USA which is considered the best instrumented country in the world?

And out of this mess of bad data and bad models I can be sure that the predictions made using this carp are useful in predicting the climate 100 years hence.

And how it is impossible to get a chaotic system modeled properly unless you know the initial conditions and the modelers admit that they have no clue about initial conditions.

I've probably only done 50 or 100 blog posts on the subject of CO2 and warming. And have probably put in 3,000 or 5,000 hours studying the matter. So no doubt I'm just an ignorant boob. Lucky for you eh?

You just tell me what to believe and I will swallow uncritically. And ignore the political agenda of the AGW proponents and their efforts to silence people with contrary views. Yep. It would be a real bitch if you came up against a competent opponent.

Did I mention that Lindzen is not the only scientist who thinks there is something to the Iris Effect? But he is corrupt and that makes any one who believes there is something to his theory corrupt. I can't wait for the show trials to start. Or perhaps we ought to burn the heretics at the stake. Or just run them out of the profession with slurs an innuendo. It has worked before.

Funny thing though. About two years ago when I would post a sceptical article I'd get lots of pro-AGWers commenting. They were always good for a traffic boost. And now? Hardly any pro-AGWers come around. It is such a disappointment for a traffic wh*re like me. Where are the defenders of the faith?

[MSimon]

And Tom,

Sadly for you, in America the unthinking masses who were at one time concerned about AGW are no longer buying it. Maybe they were fooled by the snow in Saudi Arabia this past May.

Or the cool weather in England the past few years or the lateness of spring planting this year in the USA due to rains and cool weather.

Or maybe the late start of solar cycle 24 has them spooked.

Or maybe they have been fooled by the fact that there are only six or seven long term "reliable" measuring stations in all of South America. Or none in Russia. Or China. Or Africa. Not to mention ocean surface temperatures whose method of measurement changed post WW2 and whose data was sparse and didn't follow the same track from vessel to vessel.

Or maybe they have figured out that the proponents of AGW are just as agenda driven as the opponents and have decided that none of the lot can be trusted.

I know. We can kill off a great mass of the unthinking masses with huge carbon taxes. That will serve them right for losing the faith. Hopefully once they have been punished enough they will see the light.

[tomclarke]

Simon -

I have never accused you of being corrupt. Just inclined to to let politics influence your reading of science.

Your 60 hours per blog research ratio is impressive. So you don't need to quote creeps like Lindzen, do you? You can give your own (well-founded no doubt) arguments.

I have to say that of all the stick-head-in-the-sand anti-AGW crowd I have come across you preeminently combine lucidity with a compelling rhetorical streak. It is fun to have an opponent worth arguing with - instead of everyone just shutting up when informed by me of what is clearly the the pre-ordained correct way to think .

At the end of the day: we will perhaps know significantly more about Polywell prospects in two years. You will know more about whether AGW is insignificant in a few years when the science on PDO etc vs climate models is better validated. Or perhaps, since you clearly need more than 60 hours/blog to make detailed analysis of the science, you will be convinced by a few more points on the recent climate time series.

The trouble is that each of your accusations can be rebutted, given time. It has been if you look around. But they get recycled, and proper challenge is not simple. People have written many papers on the data, correcting biasses, cross-validating one dataset against another, etc. You don't seem interested in teh boring but crucial issue of that cross-validation - how good is it, what is the evidence?

Crucially to your argument, you continue to view GCMs as stochastic models when they are physical models with free parameters which are modelled stochastically FROM INDEPENDENT PHYSICALLY DERIVED DATA. In fact often the parameters are determined by running the same (physical) model at a much finer grid so that the effects can be properly modelled instead of approximated. But parameters can then be cross-validated by comparing model fine-scale geographic temperature readings, cloud cover etc with local measurements.

So the stochastic elements in the models, because they are independent of the global time-series data that the models predict, do not make the models stochastc.

You are a good enough engineer to understand this stochastic modelling issue. You must have used models and understand the issue of over-fitting through use of dependent training and test data.

Funny thing though. About two years ago when I would post a sceptical article I'd get lots of pro-AGWers commenting. They were always good for a traffic boost. And now? Hardly any pro-AGWers come around. It is such a disappointment for a traffic wh*re like me. Where are the defenders of the faith?

They probably just got bored repeating themselves.

Best wishes, Tom

[ravingdave]

If an increase in water vapor resulted in an increase in heat, the Vector would be towards Hot in a recursive loop.

So to understand this you need some equations:

T = global tmp, at given initial CO2 & water vapour

fc = forcing from additional CO2

fw = (feedback) from additional water vapour

with coefficients Sc & Sw repectively.

So T' = T +Sc.fc +Sw.fw (T' = temp with forcing & feedback)

Also, the water vapour forcing depends on Temperature with coefficent Wt, the local derivative:

fw = (T'-T)Wt

putting these together:

T'-T = fw/Wt = Sc.fc+Sw.fw =>

fw = Wt.Sc.fc/(1-WtSw)

and total effect of CO2 forcing is therefore:

fcSc[1 + Wt.Sw/(1-WtSw)]

from this you can see that the amplification factor from the water positive feedback is finite as long as WtSw < 1. the recursive loop reaches a finite asymptote.

Your argument that positive feedback => instability is not true.

Simon, as someone who knows control, will understand this.

Best wishes, Tom

PS - I hope this clarification would sway your neutral (control theory unskilled) observer

Oh, well that changes EVERYTHING. You have an equation that says so.

If I follow your equations correctly, you are making the point that your equations won't oscillate because the positive feedback factor drops below 1.0 .

Never mind the concept that your equation is too simplistic to describe the atmosphere (Some of your coefficients should be equations themselves rather than coefficients. Where is the equation for the volumetric expansion of the atmosphere due to increased heat ? Lower heat absorption due to reduced density ? ) but it overlooks the salient point.


I'll concede the oscillating point as one not worth arguing about, because the main point is that if water were a positive feedback mechanism, the temperature would rise until it was not. (Hey ! Isn't that what i've been saying all along ? )

from this you can see that the amplification factor from the water positive feedback is finite as long as WtSw < 1. the recursive loop reaches a finite asymptote.

Were the feedback to be constant, we would all burn. Water vapor turns from a positive feedback into a negative feedback. Thanks for making my point for me. Hopefully you will be able to understand the point you just made. If not, get Simon "as someone who knows control" to explain it to you.





David

[tomclarke]

David,

The equations are quite clear. You are right they are a simplification but any complex system can be linearised for small perturbations. Equally all the other feedbacks (if fast) can be subsumed in the given coefficients.

Anyway the point is that you can get amplification from a positive feedback with gain < 1 (any electronic engineer will tell you the same thing).

The temperature rises in accordance with this, as the equations say, until there is a new equilibrium. The effect is to amplify the original forcing.

If you don't agree with this we had better leave it - I can't make it any clearer.

Best wishes, Tom

[MSimon]

So you don't need to quote creeps like Lindzen, do you? You can give your own (well-founded no doubt) arguments.

Tom,

Lindzen came up with the Iris theory. Which seems to fit the facts (net negative feedback) better than the alternative (water vapor leads to a net positive feedback).

And you have yet to refute his points that people have been ostracized and lost jobs for doubting the conventional wisdom. That is not science Tom. It is religion where heretics like Galileo are silenced.

But OK. If you stop quoting frauds like Mann and Hansen I'll leave Lindzen off my list. But that means Real Climate is not a valid resource because they are still in the Mann camp re: the hockey stick. MacIntyre pretty much shredded that with his proof that red noise fed into Mann's equations produces a hockey stick.

http://wattsupwiththat.com/2009/05/20/s ... obustness/

A central prerequisite point to this is that Steig flatly refused to provide all of the code needed to fully replicate his work in MatLab and RegEM, and has so far refused requests for it. So without the code, replication would be difficult, and without replication, there could be no significant challenge to the validity of the Steig et al paper.

Steig’s claim that there has been “published code” is only partially true, and what has been published by him is only akin to a set of spark plugs and a manual on using a spark plug wrench when given the task of rebuilding an entire V-8 engine.

That is not very scientific Tom. And it replicates the games played by Mann.

Now what kind of scientist hides his methods when proper peer review requires it? That sort of behavior calls your assumption that the science is sound into question. If climate science was a commercial venture this kind of behavior would be a strong indicator of fraud.

Now I'm sure you will bring up Polywell in this context. But all you need do to get a handle on the data is sign an NDA. Something I have refused to do in order to be able to speculate. And if my speculations get too far afield Dr. N has been known to leave subtle hints here.

[MSimon]

Anyway the point is that you can get amplification from a positive feedback with gain < 1 (any electronic engineer will tell you the same thing).

Not in any electronics I have worked with in the last 55 years but perhaps I have missed something. Care to provide a link or describe how it is done?

Tom,

I believe you are confusing positive gain with positive feedback. If this is the state of AGW climate science I think I will have to stick with my thesis that Climate Scientists are mathematically (and I'm just talking algebra now) illiterate.

[MSimon]

Most luke warmists I have come across believe the net gain in the climate system is 1.1 and the overall feedback is negative. A gain of 1.1 implies a 90% negative feedback in a non-inverting amplifier configuration. And all this assumes the operational amplifier itself has a gain >10 to get reasonable accuracy.

You might want to look into operational amplifier design to get a handle on all this as the maths are rather simple.

[MSimon]

The gain of the climate system could be positive 1,000,000 and it would not run away if the feedbacks are negative.

I deal with this in op amps all the time. Us electronicers love high gain amps. They do not imply runaway (i.e. rail to rail) systems. It all depends on the feedback and a few more esoteric points which I'm not going to deal with here - like overall gain vs phase - as they are not necessary to make my point.

[tomclarke]

OK Simon. This is not much helping matters!

It is all a matter of terminology. Better to stick to the unambiguous equations which I posted and you agree with.

In electronics, if you have a system with loop gain positive real (0 phase) and less than 1 you get amplification. This is the exact analog of the equations above. If loop gain >=1 you get oscillation.

You can call this negative feedback with 180 degree loop phase if you prefer!

David's argument was that feedback HAD to be negative. This is not true. It is indeed a question whether the feedback is negative or positive, and how large they are. Any simplistic system with water vapour would => positive feedback since watrer is a GHG but of course it is not simple due to clouds etc and you need to look at a lot of the climate modelling papers to be in a position to decide.

Tom

[MSimon]

It is all a matter of terminology.

The terminology has been pretty well set for about 60 or 100 years. It is not my fault you claim things that don't match what any poorly educated electronics or control engineer would know.

And when you make statements that you can't support (systems with gains less than one can be unstable - systems with a gain more than one must be unstable) I'm going to call you on it. Especially if you invoke what every control engineer knows.

Unstable systems (with net positive feedback) in the sense you have been using it effectively have infinite gain (at least until they reach the limits of the system).

If the climate system does not have infinite gain (very large will do) at a tripping point there will be no runaway greenhouse effect. Because below the tripping point the system would drive itself to some lower bound dependent on the system. i.e. at the tripping point the system goes from large negative gain to large positive gain. We don't see that. If you want to learn more about tripping points may I suggest a study of Schmidt Triggers. That is the electronic analogy of what you suggest. In fact these days most control problems and mechanical systems are described in terms of electronic analogies. I'd love to see the electronic analog of the climate system. With the right scaling you can make an analog computer that should do a nice job of quickly simulating the climate system. If you get the parameters right. And they are much faster than digital computers when it comes to solving some classes of problems.

One little problem with that. How do you set up a system with millions of amplifiers and hundreds of thousands of feedback paths? Well not to worry. The digital simulation guys can't do it either. Not to mention trying to use z transforms to simulate a continuous system. Which you can do reasonably well if your time and space slices are small enough. When they are not you don't get convergence. And in fact we know from descriptions of the computer runs that the results don't converge. They are highly dependent on initial conditions which even the modelers admit are insufficiently known. I suppose if your understanding of all this stuff is not deep you need to take Real Climate on faith.

What we can say is that between the limits the system normally traverses over the seasons there is no tripping point. This is especially true if water vapor feedback is supposed to have net positive feedback because water vapor responds to temperature in fairly short order.

In fact it argues that water vapor is a negative feedback term. The Iris Effect. A term coined by a scientist whose name I will not mention. You CAN look it up.

[MSimon]

Now let us look at the mechanics of the earth orbit.

Its farthest distance from the sun is: 152,097,701 km
Its nearest is: 147,098,074 km

That implies an energy input variation of about 7% over the orbital period. Far in excess of the few tenths of a percent the AGW folks postulate from CO2 increases. If water vapor feedback is fairly quick (under a month - normally stated by AGW proponents to be a few days) there is no tripping point in the current system.

Or let us look at longer periods. What causes (this is a theory) the tripping from interglacials to glacials? One is lower average energy inputs over long periods allowing ice sheets to grow causing albedo changes that further lower retained energy.

One thing we can say is that the disappearance from Greenland of the ice sheets for many hundreds of years that allowed the Vikings to settle Greenland along with the disappearance of many glaciers around the world did not cause a tripping to a significantly higher temperature regime. Nor has the appearance in Greenland of a much larger ice sheet along with the reappearance of the of many glaciers caused a tripping to a lower set point.

So if you believe the Milankovitch Cycle theory is correct we are not in a part of that cycle that is conducive to tripping point changes in climate. But you know interglacials last about 10,000 years - so we are due.

http://en.wikipedia.org/wiki/Milankovitch_cycles


And what do we see from the historical record? Exactly that. There seems to be two stable values of Earth climate with small variations within those two values. And when we do get to the next tripping point where are temperatures headed? Down. Way down. With ice sheets covering very large parts of North America.

If CO2 does what you say it does - the precautionary principle says we should be pumping it out like crazy. Cause crops don't grow well under ice.

[tomclarke]

Forgive me Simon. I know, and you know I am sure, that we are both competent enough and understand second year university electronics & control theory. So any difference on that topic must be a misundertsanding. But since you question me here is a detailed anwer:

It is not my fault you claim things that don't match what any poorly educated electronics or control engineer would know.

But then I am not a poorly educated electronics or control engineer.

And when you make statements that you can't support (systems with gains less than one can be unstable - systems with a gain more than one must be unstable) I'm going to call you on it. Especially if you invoke what every control engineer knows.

I've never said (to my knowledge) that systems with (open loop) gain less than 1 can be unstable. I have said that system with open loop gain > 1 at the frequency at which loop phase is zero (or phase 180 with negative feedback, which is same thing) will be unstable.

Unstable systems (with net positive feedback) in the sense you have been using it effectively have infinite gain (at least until they reach the limits of the system).

Well yes. It does not really make much sense to talk about it like this. Technically, while the system remains linear, system noise will be amplified since the closed loop solution to the differential equations is a positive exponential. of course at some point the system becomes nonlinear and various things may happen, but typically the system oscillates with excursions more or less into the nonlinear region according to how much greater than one is the (small signal) loop gain.

[MSimon]

I posted and you agree with.

Do I now? You should apply to the CIA at once. Because they would love to have the capability of long distance mind reading. It could come in real handy for solving some of the problems they have.

In fact I have not even gotten so far as giving your equations any more than a cursory glance. Before it can be decided if your equations have value we need to look at how feedback systems work and make some inferences from the operation of natural systems before we can even decide if the equations describe reality.

We can get there. But first we have to agree on how control systems work.

[MSimon]

Well yes. It does not really make much sense to talk about it like this. Technically, while the system remains linear, system noise will be amplified since the closed loop solution to the differential equations is a positive exponential. of course at some point the system becomes nonlinear and various things may happen, but typically the system oscillates with excursions more or less into the nonlinear region according to how much greater than one is the (small signal) loop gain.

Now we are getting some where. Is the climate system open loop? Or baring that is the feedback net positive? Evidence from the natural world please.