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Discussion > Murry Salby: Relationship Between Greenhouse Gases and Global Temperature

Missy

It sounds like you believe in the Hockey Stick graph? The last thousand years was not at a constant temperature, the medieval warm period was warmer than today with no industrial CO2.

Jul 17, 2013 at 8:27 PM | Registered CommenterDung

I don't believe I mentioned either sports equipment or constant temperatures. But your assertion is interesting. How do you know it (the warmer than today part) to be true (globally that is)?

Jul 17, 2013 at 8:48 PM | Unregistered CommenterMissy

Stop teasing me Missy ^.^

Nobody can "know" what the temperature was for the last 1000 years obviously because we did not have any way of measuring it back then. However there have been many many attempts to reconstruct temperature from proxies; items, substances or deposits that have properties that can be linked to temperature. There are also the ice core records.
Prior to the "Hockey Stick Graph" in (I think) the early nineties, the generally accepted temperature record for the last 2000 years included a Roman Warm Period (about the same as today 250 BC - 400 AD) and the Medieval Warm Period (warmer than today 950 AD - 1250 AD). Before the Hockey Stick the temperature record would have said that today's temperatures are not unprecedented and have not previously caused any problems.
Three scientists named Mann, Bradley and Hughes rewrote this record and got rid of the Medieval Warm period, suggesting 1000 years of steady temperature and then a sudden uptick.
You might ask how they did this but the 3 scientists would not release their data and methods (which should have been a heads up). Eventually their statistical methods were torn to pieces and much of their proxy evidence was found to depend totally on a small group of trees.
It has since been shown that tree rings can not be relied upon as a proxy for temperature.
I strongly recommend reading The Hockey Stick Illusion by Andrew Montford, it reads like a detective story and would explain it all to you.

Jul 17, 2013 at 9:22 PM | Registered CommenterDung

Yes, I understand equilibrium and your description is very nice, but nevertheless the analysis does not explain how removing the hose pipe (halting CO2 emissions) would make no difference to the rise in the level.

I assumed it would be apparent.

Removing the hose pipe would result in a return to the previous equilibrium, falling back from 800 pints in the bath to 750 pints in the bath (or 750 GtC in the atmosphere). The level would follow a tailing-off exponential fall from 800 to 750 with a time constant of five years.

Your numbers and assumptions are chosen to make the model work, but they are somewhat arbitrary.

No, they were not at all arbitrary.

I took them from Salby's (IPCC, presumably) slide as being authoritative (I presume) estimates of the actual values of annual natural emission and absorption of CO2 and the mass in the atmosphere.

I took 10 pints/hr (or 10 GtC/year) as being somewhat greater than the current annual CO2 emission due to fossil fuel use (as well as being easy to calculate).

As such the percentage increase you calculate seems rather meaningless. There is no particular reason to believe that sinks are directly proportional to the atmospheric volume of CO2 or that they adjust rapidly to changes.

I think there is good reason to think that absorption of CO2 from the atmosphere is pretty well proportional to atmospheric CO2 concentration. (Although I know that SkS believe otherwise.)

There is also good reason to think that the rate of absorption adapts essentially instantly to changes in atmospheric CO2 concentration.

Don't forget that I was only making the bathtub analogy to explain what Salby's differential equation says and to illustrate the results that it gives.

Jul 17, 2013 at 11:10 PM | Registered CommenterMartin A

Missy: "How do you know it (the warmer than today part) to be true (globally that is)?"
//
How do you know it wasn't (globally warmer than today, that is)?

Jul 17, 2013 at 11:13 PM | Unregistered Commenternot banned yet

Missy,
I have just caught up with your couple of references to my post, which you seem to have misunderstood.
My point was that, when looking at a complex system which has been running forever, it is instructive to look at the past.
Paleo records have their issues but the broad trends are clear: previous interglacials have been warmer than today with lower levels of CO2.
Secondly, CO2 levels rose after the temperature increased.
Third, those interglacials ended and temperatures dropped while CO2 levels were still at their peak, compared to before the interglacial.
The history also shows that the planet has had much higher levels of CO2 in the past which did not lead to catastrophic runaway warming, or else we would not be here. Temperatures have also changed much faster in the past - both up and down.
It is crystal clear that today's climate is nothing unusual, not even "unprecedented".
As for Polar bears, they were around as a species during the last interglacial when there was much less ice than today so I am not sure what you meant by your comment about their evolution.
Their numbers have increased dramatically since the 70s. Although that is coincident with the rise in temps, it is mostly due to changes in hunting regs. There's an interesting site - Polar Bear Science - which sets out the true situation.

Jul 17, 2013 at 11:38 PM | Registered Commentermikeh

Martin, maybe we are talking at cross purposes here. I may not be the sharpest girl but it is clear to me that removing the hose pipe would result in a gradual decrease etc. But that is what I was trying to get to the bottom of. I wanted to understand Salby's suggestion that the rising level of CO2 is unaffected by human emissions.

In your July 15, 10:38PM you indicated that you believe CO2 levels would still rise after a complete halt to our emissions (removing the hosepipe) as Salby suggests. In response, in my July 16, 2:07PM, I translated that into a bath analogy: "Turning off the red tap will make no difference - the bath will just continue filling. I find that baffling." Your response, did not address this, hence my apparently dumb question in my last post: "... the analysis does not explain how removing the hose pipe (halting CO2 emissions) would make no difference to the rise in the level." (note: _no_ difference). You answered by pointing out that the levels will obviously fall. Yes! but that is not what you implied earlier. Perhaps it is the analogy that is lacking, as there is no temperature element.

The number of 800GtC for atmospheric carbon in your example and the 10 GtC/a (9 GtC/a in my previous link) are indeed not arbitrary. But the 500, 150 and 750 seem to have been just for illustration of the concept of reaching a new equilibrium. The change from 750 to 800, which you say amounts to 6% do not appear to correspond in reality to the 9GtC/a for 60 years of our emissions.

Also you said of the model that, it illustrates how a quantity of CO2 released per year "bigger per year than anything released by civilisation to date" causes only a moderate (~6%) increase in atmospheric CO2. The only large quantity I see is the 150GtC/a, but this is part of the existing equilibrium, cancelled by equivalent outflows - the salient number is just the 10GtC/a (and the 6% does not seem, as I say, to correspond well to reality.

Your model illustrates well how a system returns to equilibrium after a change. One aspect of that reaction is that the speed at which the new equilibrium is reaches decreases the nearer is is. I other words the difference between the source and sink curves should gradually decrease. I am not aware of any such effect in our planetary experiment.

----

The other three comments I should respond to (Dung, Not Banned Yet and MikeH) all relate to climate history. I imagine you have rehearsed these arguments many times and I am unlikely to throw any new light on them But I find it the arguments very odd, so I'll amuse myself with a few thoughts.

Dung tells me what was "generally accepted" of the last few millennia before Mann's paper. He doesn't describe the basis for this acceptance and I don't know when rings and cores became a common research tool. So was it that there were many existing studies of ice cores, mud cores, tree-rings and whatnot and that Mann's study was just another in this series, an outlier getting very different results? Or was it that before Mann there had been no studies reaching back for two millennia and the evidence was just anecdotal - pictures of ice-skating on the Thames, Viking remains in Greenland, etc? Moreover, is Mann's study still an outlier, the only one to flatten the curve, or have there been many subsequent studies that come to similar conclusions? Coming even closer to today, we have thermometer records that tell us of rising temperatures (the blade of the stick). Unless there was more than anecdotes, you are essentially putting your faith in stories over other evidence. Personally, I have no idea whether it was warmer or colder than today in 400AD, how could I (Not Banned Yet)?

Then an interesting thing happens. We move further into the past and the record becomes more reliable. Thermometers and millennial studies are apparently wrong but MikeH jumps us from recent millennia to tens and hundreds of thousands of years ago, to previous interglacials. Lacking any stories to confuse us, we have paleo records that tell us of higher temperatures, lower CO2 (except if you believe Salby that the interglacial peaks in CO2 were as high as today's but are lost from the cores) and higher rates of change. And they are reliable enough to draw firm conclusions!

I hope you'll forgive me for finding this a little amusing :-)

On Polar bears, my point was that if you look at the taxonomy and evolution section of the Wikipedia page, it is not clear at all how old the current species is. So saying that they survived the ice age (in their current form) is a bit like saying, '"I've had this pipe all my life, although I've replaced the bowl three times and the stem twice".

Jul 18, 2013 at 2:16 PM | Unregistered CommenterMissy

"Personally, I have no idea whether it was warmer or colder than today in 400AD, how could I (Not Banned Yet)?"
//
So how can you know anything about how our current weather/climate compares to what has gone before?

At what point in time do you become able to determine a reliable metric which, in your opinion, meaningfully reflects global weather/climate?

How within that global metric do you establish reasonable and verifiable limits on regional spatial and temporal variations?

Why do you call evidence such as Thames Frost Fairs "just anecdotal"? Do you not believe they happened? Do you believe that the freezing point of water changes with time? Do you believe that they only tell you about the immediate vicinity of the Thames? How do you define "anecdotal"?

Jul 18, 2013 at 5:58 PM | Unregistered Commenternot banned yet

Talk to archeologists whose speciality is the last few thousand years. You'll be surprised how much is known about climate variations over that period.

Jul 18, 2013 at 6:13 PM | Unregistered Commentersplitpin

Martin, maybe we are talking at cross purposes here. I may not be the sharpest girl but it is clear to me that removing the hose pipe would result in a gradual decrease etc. But that is what I was trying to get to the bottom of. I wanted to understand Salby's suggestion that the rising level of CO2 is unaffected by human emissions.

Yes. Cross-purpose discussions arise especially when the people discussing don't start with a common mind set.

See if the following makes sense to you. If it does, we can push the reset button and continue. If not, the cross-purposes need sorting out before continuing.

In your July 15, 10:38PM you indicated that you believe CO2 levels would still rise after a complete halt to our emissions (removing the hosepipe) as Salby suggests. In response, in my July 16, 2:07PM, I translated that into a bath analogy: "Turning off the red tap will make no difference - the bath will just continue filling. I find that baffling." Your response, did not address this, hence my apparently dumb question in my last post: "... the analysis does not explain how removing the hose pipe (halting CO2 emissions) would make no difference to the rise in the level." (note: _no_ difference). You answered by pointing out that the levels will obviously fall. Yes! but that is not what you implied earlier. Perhaps it is the analogy that is lacking, as there is no temperature element.

That's right. I was trying to explain changes in equilibrium without complicating it by having temperature changing at the same time. I had tacitly assumed that temperature was constant so that natural emission of CO2 was constant and equal to the equilibrium absorption rate.

Salby's hypothesis, for which he provides some evidence, is that the rise in CO2 emissions, and the corresponding rise in atmospheric CO2, over the past 50 years or so, have nothing to do with human CO2 emission (except perhaps for a few per cent) and are due to global temperature rising for reasons that are not to do with CO2. (Reduced albedo due to cloud change - possibly because of cosmic ray variations? increased greenhouse effect due to water vapour? Increased solar output in the short-wavelength UV range? w.h.y? I found it interesting that I did not detect any speculation about anything in his talk.)

Including this effect would have atmospheric CO2 levels continue to rise, pretty well at current rates, even if human emissions ceased completely. (That's what Salby's analysis says - I know it is not your understanding of what happens - probably the direct opposite.)

I had not understood your red tap analogy and specially had not understood the role of the overflow. An overflow that only starts overflowing when a certain level is reached has two problems for me:

- I don't know what it corresponds to in the natural system. Nothing that I know of. Could you please explain what it corresponds to in the climate system?

- It is a nonlinear effect, if it is correct that it only starts when a certain level is reached. Nonlinear effects are very difficult to analyse if you want to understand general principles.

Is the concept of linearity familiar to you? If not, then I must either briefly explain it or avoid using it (explicitly or implicitly) in trying to explain things..

The number of 800GtC for atmospheric carbon in your example and the 10 GtC/a (9 GtC/a in my previous link) are indeed not arbitrary. But the 500, 150 and 750 seem to have been just for illustration of the concept of reaching a new equilibrium. The change from 750 to 800, which you say amounts to 6% do not appear to correspond in reality to the 9GtC/a for 60 years of our emissions.

Also you said of the model that, it illustrates how a quantity of CO2 released per year "bigger per year than anything released by civilisation to date" causes only a moderate (~6%) increase in atmospheric CO2. The only large quantity I see is the 150GtC/a, but this is part of the existing equilibrium, cancelled by equivalent outflows - the salient number is just the 10GtC/a (and the 6% does not seem, as I say, to correspond well to reality.

By "bigger per year than anything released by civilisation to date" I meant "bigger per year than anything released by civilisation to date" ie more than has been released in any one year.

It's what Salby's equations say happens. And it corresponds to his view that human CO2 plays a negligible part in things. But it does not correspond to your understanding of how things work.

Your model illustrates well how a system returns to equilibrium after a change. One aspect of that reaction is that the speed at which the new equilibrium is reaches decreases the nearer is is. I other words the difference between the source and sink curves should gradually decrease.

That's correct - the return to equilibrium (assuming a linear 1st order differntial equation as Salby assumes) is an exponential curve, the slope of the curve diminishing as equilibrium is apporached.

I am not aware of any such effect in our planetary experiment.

That's because the circumstances have not arisen where it could be observed. That does not mean the effect is theoretically impossible or it is nonsense to analyse the circumstances under which such an effect would occur.

Does the foregoing reduce or increase the cross-purposes?

Jul 18, 2013 at 6:37 PM | Registered CommenterMartin A

I am afraid I see Missy as a bogus player here, someone knowing much more than they let on and just messing us about.

Jul 18, 2013 at 9:01 PM | Registered CommenterDung

Dung, reading between the lines here I agree with you that "Missy" is playing a curious game, not sincere and not forthcoming. Troll games are not always harmful, though, as long as other participants recognize what is going on and don't mind spending the time. It can still be useful to see what arguments and information emerge on such a thread, but folks should not think that "Missy" is playing it straight.

Jul 18, 2013 at 10:09 PM | Registered CommenterSkiphil

One characteristic of such games is a level of knowledge that seems to vary greatly from moment to moment.

Of course, a lot of blog discussion is a game of one sort or another.

Jul 18, 2013 at 10:46 PM | Unregistered Commentersplitpin

You've only *just* realised?

Jul 19, 2013 at 9:54 AM | Unregistered CommenterTheBigYinJames

I remember a long time ago in the early days of the web, someone devised an online IQ test which asked a long series of questions. After a while it became apparent that the questions were just going to go on and on forever. The IQ was calculated by how many pages into the test you went before you abandoned it.

Jul 19, 2013 at 9:57 AM | Unregistered CommenterTheBigYinJames

The overflow was not intended to be non-linearity, as I said that before turning on the red tap, water was dribbling from the overflow. I added the overflow to allow for increased outflows when the inflows increased. This was not as elegant as your model where the outflow size changes according to the volume, but I wanted a real physical (as opposed to a conceptual) analogy.

I still don't see what in your description is bigger **per year** than anything released by civilisation to date. The only things bigger than 10GtC per year are the natural flows that, as I said, are part of the existing equilibrium and which cannot be said to contribute to any increase.

---

Others are clearly having trouble reconciling their respect for the accuracy of proxy reconstructions spanning hundreds of thousands of years with their dismissal of those that span just few thousand years (and their distrust of thermometers). Rather than attacking me, you should perhaps first resolve this inner conflict. If you think all short term reconstructions and temperature measurements have been corrupted by warmists then explain why they didn't bother to doctor the longer term results.

Jul 19, 2013 at 1:15 PM | Unregistered CommenterMissy

The overflow seems nonlinear to me as its flow could be zero while the bath content is non-zero.

My table of total fossil-fuel CO2 only goes up to 2009 but shows less than 10GtC per year in each year:

2000 6766
2001 6929
2002 6998
2003 7421
2004 7812
2005 8106
2006 8372
2007 8572
2008 8769
2009 8738

Hence my saying (10GtC) > (anything released by civilisation to date). If you add in 'land change use', it might be marginally above 10GtC for recent years.

BYIJ: IQ = 100.0/Np ?

Jul 19, 2013 at 6:04 PM | Registered CommenterMartin A

TBYJ

As Skiphill pointed out, you can sometimes gain from the situation and also you can be wrong in your judgement. My position is that I have lost patience and so stated my opinion on Missy.

Jul 19, 2013 at 8:15 PM | Registered CommenterDung

Ah, its the 10GtC that is greater than anything released. I understand now what you mean. But the 6% refers to a rise from an apparently arbitrary 750GtC to the actual 800GtC and so seems insignificant to me. On overflows, I did say that water was dribbling from the overflow, so the initial flow was non-zero. It was a contrived analogy I suppose :-)

Dung, you have lost 'patience' with me but still have 'faith' in Salby. Is your position on the subject just driven by emotion, rather than understanding or fact? If so, it is unsurprising that you can accept or reject different evidence obtained using the same methods according to how well it fits your desired result. Perhaps we all do that to some extent.

Jul 20, 2013 at 1:18 PM | Unregistered CommenterMissy

As I said before, the numbers I used were not arbitrary.

The 750GtC is what the IPCC slide used by Salby gives as the atmospheric CO2, presumably prior to growth of fossil fuel emission. Using Salby's differential equation then gives the result that starting to emit fossil fuel CO2, at a constant rate of 10GtC per year, would result in a 6% rise, after which there would be no further rise in atmospheric CO2.

Would you like to help me make sense of the SkS mass balance argument that says it shows the increase in atmospheric CO2 is due to human actions? To me it seems a plausibility argument rather than a definite proof. If it really is a proof, what is the step I am missing?

Also, I'm trying to re-read Gavin Cawley's (SkS writer who produced the mass balance argument) paper where he says that the differential equation dC(t)/dt = -alpha C(t) is wrong. This is the same equation as used by Salby. Gavin Cawley gives a nonlinear differential equation instead (which I think he believes is not a nonlinear equation). He also seems to make some implicit assumptions in the reasoning that, so far as I can see, have no way of being verified. I'd like to know if I'm correct on this.

Jul 20, 2013 at 5:53 PM | Registered CommenterMartin A

I'd like to help, but I don't see how to. To me it seems self evident that if concentrations are increasing every year and we are emitting at twice the rate of increase, that our emissions are the cause of the rise. The SkS page essenhigh_rebuttal.html has many comments and explanations. I doubt I can add anything useful :-(

Jul 21, 2013 at 3:35 AM | Unregistered CommenterMissy

Murry Salby's private and employment history is of no consequence when judging his science. The fact that he has been so violently attacked personally indicate to me just how the vested interests are afraid of his ground breaking science. I have to date not seen any sound scientific rebuttal of his science, as presented, hence the ad homme attacks. I think that one problem that has come to light on this thread is just how diverse the science is. I believe it needs a multi-disciplinary panel to examine and debate it. It is a great pity that Prof. Salby cannot contribute to the debate personally. Finally to attack any scientist personally in an attempt to distroy his SCIENTIFIC credibility is beneath contempt.

Jul 21, 2013 at 5:35 PM | Unregistered CommenterRoss Lea

Ross, would you be able to judge the soundness of a scientific rebuttal of Salby? Do you understand the science and maths behind it and that behind the rebuttals? If so then you can perhaps explain to Martin what he is missing in the mass balance arguments.

I think Salby probably has very little credibility among climate scientists anyway, but your last sentence is a good sentiment. Does it apply equally to all climate scientists, Mann and Jones for example?

Jul 22, 2013 at 12:29 AM | Unregistered CommenterMissy

Missy

I think I made the point that no one scientist however qualified can embrace all the science. Personal attackes on scientist are dispicalble from what ever source. I think I have enough experience to judge a scientific argument. To quote Samuel Johnson "You may scold a carpenter who has made you a bad table, though you cannot make a table" .

Jul 22, 2013 at 11:21 AM | Unregistered CommenterRoss Lea

Martin A

Sorry I seem to have diverted your discussion threat. I have said my piece and have no more to contribute.

Jul 22, 2013 at 11:25 AM | Unregistered CommenterRoss Lea