Martin,

I was just giving a few ways that AGW could be falsified and that sceptics continually try to use for that purpose. I didn't say they were true - how could I?

> Huh? Back radiation exists. People who say it does not
exist are - shall we say - lacking an understanding of
elementary physics.

It is a sceptic staple as far as I can see. I've seen discussions of this in various sceptics places. You might not like it, but that changes nothing.

> Simon's point was, as I understood what he was saying,
that when the AGW due to human released CO2 was announced
to the world, the people who formulated should have
said

That would be Arrhenius would it?

> As Simon said "... climate scientists who do study the
subject have failed to advance into testable, falsifiable
theory".

So in what way is it not falsifiable? I've suggested a few ways and sceptics constantly suggest more. What more is it that you want?

Chandra,

We did have a reasonable dialogue and certainly don't feel we alienated each other in any way. My question above, I felt, was also reasonable.

I will gently ask it again.

Can you please provide me with a sense of your level of science education? It for me is to gauge your familiarity with scientific methodology. Nothing more.

I perform a very significant amount of teaching in my work and this knowledge of your depth of understanding would allow me to gauge where to pitch my own questions?

I hope that makes some sense to you. There is NO point scoring at work here. I would ask the audience to please respect this approach too.

You cannot have felt other than comfortable with me Chandra (no Rodent, not as toy-boy even!) and part of you I would hope can see that greater understanding all round can only strengthen your own ego-structures.

Please Chandra. Would you kindly clarify?

Andy

"It is an energy-retentive gas. " Even that would be misleading to anyone who did not fully understand your last statement.

Only a short step from your sentence to Dr Willet stating, with a straight face 'CO2 traps heat".

Simon, for citations just search these pages for mdgnn, I'm not doing it for you. And consider the fact that whenever "radiative physics" comes up the Bishop asks that it be taken to the discussion forum. It has been discussed so much that he has tired of it.

What is your preccupation with religion? I see it as being irrelevant here and will not enter into a discussion.

Also, thanks for your handy summary, although I don't see the significance of your percentages to your argument. As I understand it, you are prepared to accept the basic correctness of Arrhenius that a doubling of CO2 will cause only about a 1.2C rise in temperature; you consider 1.2C to be harmless; and you do not accept that any mechanism has been shown to exist that would case a further rise (for a doubling of CO2). Did I understand you correctly?

Jones, I have no scientific background beyond high school. Happy now? Cue the journalist types on the blog accusing me of scientific illiteracy, to go with my economic illiteracy.

Simon, I can well understand your desire to disown the radiative physics sceptics such as mdgnn. They do seem to be total cranks. Are there other parts of the broader climate sceptic world that you disown when presenting your preferred narrow scepticism as the whole of scepticism? Do you disown the ones that think climate science is a hoax? Or those who think the earth is cooling, not warming? Or those who think cosmic rays are the cause of recent warming? I could go in but it would be easier if you were just to identify who and what you consider bonafide sceptics. What are the necessary views?

> The percentages are what they are. Why would you
have an issue with them?

I have no interest in them, and I don't see why they influence Arrhenius' work or modern conclusions from that work. That is why I said, "I don't see the significance of your percentages to your argument". You have enlightened me no further.

> All the questions you've asked have been well answered.

Really? I must have missed it. For the benefit of the discussion can we take it that you accept the basic correctness of Arrhenius that a doubling of CO2 will cause only about a 1.2C rise in temperature; that you think a 1.2C rise will be harmless; and that you do not accept that any mechanism has been shown to exist that would case a further rise (for a doubling of CO2)?

> I don't think there is scientific/economic disagreement in
principle that warming of <=2 degrees C is broadly net
beneficial. Do you have some basis for disputing this
congruent figure?

I think nobody knows that with any certainty. I certainly don't take Tol's meta-analysis very seriously as it relies almost entirely on the results for 1C warming in his 2002 study for the shape of the resulting curve.

Chandra

I not only genuinely thank you for that response but your "stock" truly has just shot up in my eyes.

You are far far braver than the usual commentator who might grace these pages with some snide comment or other or a real attempt at trolling. I have not categorised you such and am convinced of my own view.

You choose to enter an arena where there are, lets face it, some VERY knowledgable people indeed which will naturally generate an anxiety in you and yet continue to fight your corner...That shows real strength of character.

The fact that I happen to think you are wrong in your view does not make me necessarily correct..I may be just as wrong as i think you are....but so what?

With respect to scientific " illiteracy" as you put it the blunt truth is that in this specific area I am almost as " illiterate" as you are. Your view is still to be respected. History is replete with highly respected and VERY scientifically literate people also making a complete pigs ear of even their own fields!

Simon makes some most excellent points above. Please consider them as best you can.

Economic illiteracy? Me too in exactly equal measure Chandra. I'm a "wet-and-bubbly science" man not a financial adviser!!!

I was educated beyond high school science only at the age of thirty so you have little to feel vulnerable with there.

Although I will continue to think that your position will not stand the test of time I do not think you will be too scarred by such.

I will still ask that you really try to not feel too provoked in these pages but keep arguing as best you can and retain always a significant streak of doubt as to what you currently hold true. That would also serve you well in the future.

Cheers

Andy

Simon, I did not mean to imply that all percentages are of no interest to me, just those you quoted, which seem to have no relevance to the discussion.

> I have no desire or need to vilify or disown anyone.

No of course not. And so as the radiative sceptics are a part of the sceptic firmament, their arguments are a sceptic staple, as I said.

> NO mechanism has been ...

I seem to remember reading about water vapour feedbacks, methane feedbacks and feedbacks from changes in albedo through ice loss. These seem to fit the bill. We are of course currently testing these on a planetary scale, which is arguably rather a silly thing to do. Rather like testing in a lab where the lab itself might be damaged by the experiment. But at least one can build a new lab.

I am guessing that this obvious current testing phase is not acceptable to you. You want a test that can show the results of a planetary-scale experiment, with planetary time scales but that can give you the result you want in a politically relevant time frame. In that quest you are probably going to be disappointed.

But it sounds vaguely feasible to test the albedo feedback to a first approximation - you just need an environment where you can vary the albedo and see whether more heat is absorbed. A suitable water-based comet or moon would suffice if we could arrange to instrument it and then spray half of it black to see what effect that had. A nice project for an inventive engineer, but funding might be a problem - after all I imagine the result is already known with fairly high probability so the project might seem frivolous.

I guess we could imagine doing the same for the methane feedback if we can create or find a suitable planetoid with sufficient frozen methane. We could arrange for the methane to be gradually melted and see whether this raised the temperature of the planetoid and see how much methane we needed to melt in order to raise the temperature sufficiently high to make the process self sustaining. Of course funding would again be a problem, again because we almost certainly can model this accurately and know the result already.

But anyway, there are some early ideas for you from a scientific illiterate. I imagine those with science degrees can do better, assuming they also have imagination. As you know falsification strategies for hypotheses do not need to be practicable for the hypothesis to be widely accepted - evidence some of Einstein's predictions only becoming testable in recent decades .

By the way, I'm sad that you didn't discuss Tol's meta study. I would have been interested in your defence of it.

Martin A, I think you are correct. I believe MDGNN has significant industrial experience of taking IR measurements and building devices to do so. Most of what he says makes sense to me.

But he tends to fall down by 1) leaping ahead with the argument and losing his audience 2) Using terminology that is unfamiliar to the audience, and later appears to change, and 3) Repeating his main point so often that people get irritated he gets comments snipped and becomes frustrated. All common problems in 'communicating science', I guess.

Like other people, I wish he would get a blog and lay out his ideas coherently so that interested readers can ask detailed questions, because I think his points merit consideration.

We have been told that Arctic ice melt was 30 years ahead of the models from 2007 so we're 30 years into the ice tipping point. When it comes to methane trapped either in the permafrost or the hydrates under water the research papers alternately predict catastrophe, not going to happen or already happening and it hasn't had an effect. The recent IPCC report didn't promote the idea.

http://joannenova.com.au/2013/10/ipcc-says-abrupt-irreversible-clathrate-methane-ice-sheet-collapse-are-unlikely-or-unknown/

The water vaour feedback idea is not working well either since the atmosphere has partly done the opposite to the predictions.

http://wattsupwiththat.com/2013/03/06/nasa-satellite-data-shows-a-decline-in-water-vapor/

Simon,

> Yes, they're called "tipping points".

No, "water vapour feedbacks, methane feedbacks and feedbacks from changes in albedo through ice loss" are not called tipping points, they are called feedbacks. There's a hint in the word 'feedback' in each one. Tipping points as a result of some feedbacks have been hypothesised.

> But if what you say is true then climate science isn't a
"science" in any normal sense of the word.

As I said, there are ways that the feedbacks can be tested. They might be impractical with current technology and they might take a long time. But they are clearly testable. Or we can just think about it: does ice reflect more than water, do rising temperatures cause a loss of ice and does less ice mean the oceans will absorb more heat and does that mean that ice loss will result in more warming and hence more ice loss? Or, will temperature rises that melt permafrost release any trapped methane and also result in decomposition of exposed soils, is methane a greenhouse gas and so will permafrost loss cause the emitssion of extra methane or CO2 and hence extra temperature rise and permafrost loss? These feedbacks seem quite clearly present, although it is doubtless difficult to quantify them. Whether there are tipping points somewhere along the way is irrelevant to whether there are known feedbacks.

> I found Matt Ridley's assessment of Tol's analysis well
reasoned and convincing. I haven't seen anything to
counter it which is at all compelling.

So as I have said elsewhere, Tol's graph (shown on one of the recent BH blog posts) consists of 14 data points from various studies. 3 of these are positive (net gains from warming) and the rest are negative. Only one of the three is significantly positive, Tol's 2002 study at 1C. So the nice curve plotted by Tol between the various data points relies entirely on his 2002 study for giving it an initial rise (gains from warming). Do you normally accept graphs as good evidence when they would look quite different after the removal of a single data point? It is a silly question I know, as all of the graphs of temperatures where sceptics rely on the change since 1998 would look quite different if that single data point were removed. Conclusion: sceptics only require a single data point in their favour to be completely credulous of the resulting graph...

TinyCO2, as you might imagine, I don't really believe anything written on Nova or Watts sites is not either a partial reporting of the facts, a misunderstanding, an outright fabrication or a combination of the three. Just like you probably don't believe SkS, RealClimate or Tamino etc. Just for balance here's an SkS link on humidity:

http://skepticalscience.com/humidity-global-warming.htm

That should have been this link