By William and Gavin
On Thursday March 8th, the UK TV Channel 4 aired a programme titled “The Great Global Warming Swindle”. We were hoping for important revelations and final proof that we have all been hornswoggled by the climate Illuminati, but it just repeated the usual specious claims we hear all the time. We feel swindled. Indeed we are not the only ones: Carl Wunsch (who was a surprise addition to the cast) was apparently misled into thinking this was going to be a balanced look at the issues (the producers have a history of doing this), but who found himself put into a very different context indeed [Update: a full letter from Wunsch appears as comment 109 on this post]
So what did they have to say for themselves?
CO2 doesn’t match the temperature record over the 20th C. True but not relevant, because it isn’t supposed to. The programme spent a long time agonising over what they presented as a sharp temperature fall for 4 decades from 1940 to 1980 (incidentally their graph looks rather odd and may have been carefully selected; on a more usual (and sourced!) plot the “4 decades of cooling” is rather less evident). They presented this as a major flaw in the theory, which is deeply deceptive, because as they and their interviewees must know, the 40-70 cooling type period is readily explained, in that the GCMs are quite happy to reproduce it, as largely caused by sulphate aerosols. See this for a wiki-pic, for example; or (all together now) the IPCC TAR SPM fig 4; or more up-to-date AR4 fig 4. So… they are lying to us by omission.
The troposphere should warm faster than the sfc, say the models and basic theory. As indeed it does – unless you’re wedded to the multiply-corrected Spencer+Christy version of the MSU series. Christy (naturally enough) features in this section, though he seems to have forgotten the US CCSP report, and the executive summary which he authored says Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human induced global warming. Specifically, surface data showed substantial global-average warming, while early versions of satellite and radiosonde data showed little or no warming above the surface. This significant discrepancy no longer exists because errors in the satellite and radiosonde data have been identified and corrected. New data sets have also been developed that do not show such discrepancies. See-also previous RC posts.
Temperature leads CO2 by 800 years in the ice cores. Not quite as true as they said, but basically correct; however they misinterpret it. The way they said this you would have thought that T and CO2 are anti-correlated; but if you overlay the full 400/800 kyr of ice core record, you can’t even see the lag because its so small. The correct interpretation of this is well known: that there is a T-CO2 feedback: see RC again for more.
All the previous parts of the programme were leading up to “so if it isn’t CO2, what is it?” to which their answer is “solar”. The section was curiously weak, and largely lead by pictures of people on beaches. It was somewhat surprising that they didn’t feature Svensmark at all; other stuff we’ve commented on before. Note that the graph they used as “proof” of the excellent solar-T connection turns out to have some problems: see figure 1c of Damon and Laut.
Along the way the programme ticked off most of the other obligatory skeptic talking points: even down to Medieval English vineyards and that old favourite, volcanoes emitting more CO2 than humans.
It ended with politics, with a segment blaming the lack of African development on the environmental movement. We don’t want to get into the politics, but should point out what the programme didn’t: that Kyoto exempts developing nations.
[Also: other discussion at InTheGreen, Stoat, The Guardian and
Media lens.]
[Update: What Martin Durkin really thinks!]
[Update for our german readers: A german version of the “swindle” film was shown on June 11 on German TV (RTL); here is a german commentary by stefan.]
Ike and Mark (#143, 144), thanks for your comments. Just to clarify though, it wasn’t me who needed an explanation of how the greenhouse effect works, although Ike’s summary is excellent and I’ll probably use it as a template; but it was that I sometimes have difficulty translating the jargon when I’m trying to explain things to open-minded sceptics who are not scientifically minded, for whom mention of the models except when absolutely necessary is a turn-off. Can I get away with saying “driving force” and “amplifier” instead of “forcing” and “positive feedback” in that context, do you think? And if so, can you think of a layman’s word I could use when talking to such people, instead of “negative feedbacks”?
Re. proxies, I think the word implies something more specific than “indirect evidence” does. For instance if I say “vineyards are not a good proxy for temperature” it means more and sounds better than “vineyards are not good indirect evidence for temperature” (which sounds like a double negative apart from anything else). Could I perhaps use the word “indicator” as a direct substitute for “proxy”, do you think?
Dave
The Great Global Warming Swindle is being shown again this evening (Monday 12 March) at 10:00 pm on More4 and is described on their website http://www.channel4.com/listings/ as a “Polemical film challenging the consensus that man-made CO2 is heating up the earth. Featuring leading academics, the film questions the science behind the accepted reasons for global warming and argues other explanations for climate change are not being properly aired.”
Perhaps we should be pressing for a disclaimer at its start…
Dear RC
Are programs like this one and refuting the skeptics along with AGW’s preceived political and economic implications the reason why serious/abrupt (non linear) climate change is absent from the recent IPCC report and literature?
Here is one example, ice dynamics. It is assumed that Greenland and Antartica are large scale bodies of ice that will take a long time to change in any significant way. However if ice synamics are inherently non linear then rapid non linear collapse of these ice bodies could kick in or play out sooner than thought.
Another one is peat bogs in siberia (melting permafrost) and other bodies of rotting vegetation that could accelerate rapid change if the temperature rises much more.
Is climate change actually running faster than projections and models are indicating in any area at all?
Re #109
While I feel a little sorry for Carl Wunsch, we should all be a little sceptical not only of what the popular media publishes, but what they say to us in private. Recently, I had an email from a UK broadcaster asking me for an interview. I was concerned that they might just want an ‘Aunt Sally’, and made clear that I was not interested unless there was a clear commitment to balance. An effuse email followed promising balance and a list of the numerous others with views similar to mine who would also contribute. I accepted and put some effort into preparation.
Before I was to set off to the interview location, I watched Nigel Lawson being interviewed. He described alarmism as the Da Vinci Code of climate research, and poured cold water on the hysteria, to which Sky’s week long ‘Green Britain’ programme was so obviously committed. He was a bit of a killjoy, and I guess and they did not want any more. Soon after, I had a call to say I was no longer needed. So much for a promise of balance. Many alarmists and not even a handful of sceptics in hours of programming.
But what was Carl Wunsch’s beef? Presumably he would be happy to be the voice of caution on an alarmist programme with all you RealClimate guys? Should factual but inconvenient uncertainties only be presented as footnotes or asides in programmes presenting and stressing the ‘consensus’ hypothesis and declaring the debate over?
[Response: Not at all. But ‘polemic’ is not a good way to present science since all the usual caveats disappear and you can end up with dishonest programs like this one. I would point you to our discussion of the ‘Global Dimming‘ documentary for our equally trenchant criticism of ‘polemic’ from the other side. Telling it straight should be the guideline (in my opinon) – and that includes showing that there is indeed a consensus on the main issues and the vast amount of data that supports that, but also pointing out the real uncertainties and concerns – not the faux pseudo-debates highlighted here. Maybe that is just not as interesting to some documentary makers. – gavin]
hopp — you’re a “radical green” who supports nuclear power and doesn’t believe anthropogenic global warming is happening? This must be some strange new definition of “radical green” I never heard before.
[[Q1: If there is a feedback mechanism, what stops it accelerating exponentially?]]
It’s a converging series, not a diverging one. The series 1 + 1/2 + 1/4 + 1/8… is an infinite series, but it only sums to 2 no matter how many terms you take into account.
[[ Holding back emerging economies from developing would certainly condemn another generation to grinding poverty and early death. ]]
Who wants to “hold back emerging economies from developing?” Are you under the impression that economies can only develop using fossil fuels? Where did you get that idea?
[[Even Einstein held faith in his special theory in face of growing evidence.]]
WHAT “growing evidence?” Evidence that relativity isn’t true?
[[what role could the absolute increase of global water content play, if any? Has this been considered in any way? ]]
If there is more water vapor in the atmosphere, the surface is hotter, all else being equal, since water vapor is a greenhouse gas. But its short residence time in the atmosphere means it is very difficult to manipulate. We could double the water vapor in the atmosphere tomorrow and the extra would be almost all gone in a month. The thing to watch with water vapor is the temperature — the hotter the world, the more water vapor in the atmosphere, according to the Clausius-Clapeyron law. And of course the water vapor adds more heating, which adds more water vapor, etc. But it’s a converging series.
[[If there is a positive CO2 feedback that did not lead to instability, and it aparently did not, either of a runaway or limit cycle, then there must be some counterbalance, a negative feedback which is stronger than the positive feedback of the CO2 release. ]]
That is a non sequitur, and makes me strongly doubt your claim to be familiar with how feedbacks work. Any positive feedback that converges stops all by itself; it doesn’t require a second feedback to counteract it. The math is as simple as a converging series versus a diverging series.
If CO2 greenhouse warming is not linear, and the first 100 ppm increase in CO2, feedback from, ended the ice age (4.0C to 8C contribution) and the next 100 ppm over the last century added a further 0.8C – isn’t the next 100 ppm going to have a small effect?
Has temperature already increased about as much as it can?
190 to 290 ppm – 8.0C
290 to 384 ppm – 0.8C
384 to 550 ppm – 0.1C
It is either that or all the explanations regarding feedback for the interglacial warming and the recent warming do not add up.
Re: #160 John Lang
As has been made clear many times here, the increase of CO2 is not the only factor warming the planet during deglaciation. So, of the 5 deg.C global warming during a deglaciation, not all 5 are due to CO2. Hence in the “180 to 280” row the number should be less than 5.
It’s also been made clear here many times that the planet hasn’t yet responded to all the warming that’s “in the pipeline” from the greenhouse gases we’ve already put up there. Hence in the “280 to 380” row the number should be greater than 0.8. Based on estimates of climate sensitivity, it should be around 1.4.
It seems to me that you have a tendency to massage numbers. For example, for deglaciation you say 4 to 8, but I consistently see 5 in the peer-reviewed literature and have never seen more than 6. Then from the “4 to 8” range, you put 8 in your table. Also, in a previous post (#101) you claimed that adjustments to temperature records increased the trend by 0.5 deg.C — James Hansen and colleagues disagree with you.
Sorry, Gavin, yes it is. I’m sorry, but I’m no climate scientist (microbiology degree but years ago) and it simply isn’t simple.
Could you please describe, without acronyms or talk of “Milankovitch forcings”, how it is that a temperature rise that leads to higher CO2 in the atmosphere which leads to more warming (an extra 4,200 years, as you say) then collapses into an ice age?
Surely the world should continue warming, which continues to force CO2 into the atmosphere, which continues to warm, etc.? I can see that you might get increased vegetation growth that might lead to increased CO2 fixing but it doesn’t sound like it should be enough to force such a massive drop in temperature.
DK
[Response: I didn’t mean to suggest the ice-age carbon cycle changes were simple. Indeed there is still substantial uncertainty in how the various changes occur. The ‘simple’ idea is that there are two effects: CO2 affecting climate (which is supported by observations, theory and modelling) and a separate effect of climate on CO2 – for which we have observations from the ice cores. The processes by which the climate – CO2 effect works are basically a reduction in terrestrial biomass (which puts CO2 into the atmosphere), an increase in ocean carbon (which takes it out). The process by which the ocean takes up carbon consists of the solubility effect (colder oceans take up more carbon dioxide), and also changes to biology (increased production can lead to more export of carbon to the deep ocean). The biological changes are complicated and will be affected by increased windiness, possibly increased dust flux (as a source of micro-nutrients) and changes to mixed layer depths etc. As you might imagine the biological changes are the least well understood. -gavin]
Here’s some math on how climate feedbacks work.
The increase solely from radiative transfer factors, for CO2, is about 1.2 K from doubling (Houghton 2004). This gets multiplied by the “gain” from several feedbacks. Feedbacks are fractions less than 1, and are summed before being inserted in the gain equation:
G = 1 / (1 – sum(fi))
Here are the feedback factors used in the GISS (NASA Goddard Institute for Space Studies) and GFDL (Princeton’s Geophysical Fluid Dynamics Laboratory) global climate models c. 1990:
Process GISS GFDL water vapor/lapse rate 0.40 0.43 cloud 0.22 0.11 ice/albedo 0.09 0.16 ---- ---- Total: 0.71 0.70So inserted in the gain equation, these factors yield a gain of 3.44 for the GISS model and 3.33 for the GFDL model. This gives a climate sensitivity of 1.2 x 3.44 = 4.1 K for the first model and 4.0 K for the second.
[Response: Note these are not the factors ‘used’, but the factors derived from the GCMs and will vary (slightly) as the models develop. The current GISS sensitivity is 2.7 deg C. – gavin]
[[Has temperature already increased about as much as it can?
190 to 290 ppm – 8.0C
290 to 384 ppm – 0.8C
384 to 550 ppm – 0.1C
It is either that or all the explanations regarding feedback for the interglacial warming and the recent warming do not add up. ]]
There’s a third choice: You’re applying a relation between CO2 and temperature which ignores all the confounding factors. The ice age warming was overlaid on a warming due to a change in insolation distribution (the Milankovic cycles). The current change was in the face of a big negative aerosol forcing for 1940-1970. And I don’t know where you got the third figure.
The comments left can be really frustrating to someone who is intimately aquainted with these matters, as am I.
#160 said:
“[[If there is a positive CO2 feedback that did not lead to instability, and it aparently did not, either of a runaway or limit cycle, then there must be some counterbalance, a negative feedback which is stronger than the positive feedback of the CO2 release. ]]
That is a non sequitur, and makes me strongly doubt your claim to be familiar with how feedbacks work. Any positive feedback that converges stops all by itself; it doesn’t require a second feedback to counteract it. The math is as simple as a converging series versus a diverging series. ”
Yes it does. This is fundamental to how limit cycles work. Let’s take the equation
xdot = a*x
where “a” is a gain which decreases in time. The solution is x = x(0)*exp(integral(a*dt)). At time T, “a” goes to zero. Let A(T,0) = exp(integral(a*dt)) from zero to T. Now, the state is at x(T) = A(T,0)*x(0) > x(0). What pulls x(T) back down to x(0)?
In a limit cycle, an instability tends to pull the system to its limits where the instability vanishes and negative feedbacks pull it back down again, at which time the instability reasserts itself and pushes it back up again. A time lag between the time the instabillty vanishes and reasserts itself allows a cycle to be established. This is so fundamental and elementary, I am embarrassed on your behalf for making the comment.
Gavin wrote:
“[Response: Please read the linked post again. You can think of negative feedback as a series where each perturbation has an opposing effect i.e. 1-r+r2-r3… and positive feedback where each perturbation is additive 1+r+r2+r3… Negative feedback is always stable (the series converges to 1/(1+r) which is always less than 1), while positive feedback will only converge to 1/(1-r) (> 1) if r is smaller than one. The point is that positive feedbacks are often bounded – which is a good thing. – gavin]”
No, that is not how this stuff comes about. Positive and negative feedbacks are couched in terms of continuous time systems. In the difeq above, if “a” is positive, it is a positive feedback. If “a” is negative, it is a negative feedback. There is no positive/negative divide in discrete time systems. I can have
x(k+1) = -2*x(k)
where “k” is the index. Each term in the series has an opposing, negative effect, but the series is divergent. Similarly, I can have
x(k+1) = 0.5*x(k)
The the gain is positive, yet this series is convergent. If you have a system described by the difeq above, then at discrete instants t(k), the solution is
x(t(k+1)) = A(t(k+1),t(k))*x(t(k))
If the continuous time gain “a” is a negative feedback, then A(t(k+1),t(k)) has magnitude less than one, and the system is stable. If it is positive, A(t(k+1),t(k)) has magnitude greater than one, and the system is unstable. This is why stable discrete time systems are seen to map the left half of the complex plane, the region of negative feedbacks for continuous time systems, into the unit circle, the region of stability for discrete time systems. This is how the entire nomenclature of “positive” and “negative” feedbacks came to be.
Do you climate guys work with people versed in stability theory, or are you just winging it? This is all very, very elementary stuff. I think you need to get some such people in your working group because it is becoming apparent to me that there are some very thorny issues here which are not being properly taken account of.
[Response: You are not solving the appropriate equation. I recommend Hansen et al 1984 for an explanation and definition of terms that is better than I can squeeze in here. – gavin]
[Response:AFAIK, people don’t know exactly why CO2 stopped at 280 in interglacials and 180 in glacials. It doesn’t have to be feedbacks: there could simply be some reservoir that is exhausted. Also, thats for the previous 4 interglacials: before then, EPICA shows 250. This again is unexplained – William]
Gavin – it makes no sense to talk of “negative” and “positive” feedbacks for discrete systems without analogy to continuous systems because the criterion for stability in discrete time systems is “gain magnitude less than unity”. As you can easily see in my example above, it is possible to have a negative gain in a discrete time system and yet have instability. The dividing point is unity gain, not positive/negative. If you guys have reinvented the wheel and come up with a new nomenclature all your own, then you have a vast archive of knowledge to reinterpret.
William – it does not matter if the CO2 petered out. Upon cooling, it should have been reabsorbed, then re-released to warm things up again in a classic limit cycle. That it did not is an important clue you guys should be using to further your understanding of the phenomenon.
So you comment on a post that was censored? Yes, I am a green. And I try to think like a tree. With several branches, and falling leaves. Non-linear, several competing variations, complex, with doubt, self-criticism and uncertainty.
It’s only a healthy approach, because, behind the surface, most of our so called knowledge is about trusting others/authorities/sources. Who/what do you trust? And why?
I have professional interest in AGW from such a perspective, and at the same time I’m a green. No problem. You can be many things. Don’t be a grey, one-coloured, dull rock with your book burning antics and holocaust comparisons.
I do know that I made valid points about the interpretation process. I’d like to see the AGW process naked, without the political load. When you read about the research on AGW you are all the time faced with speculation, interpretation, probabilities. As a philosopher I do know that these do not go hand in hand with such absolute certainty. By preaching to people like some religious fanatics who are always right, always have the answers, always sound so 100% certain (look in the mirror gavin) you are turning people off.
I watched the Channel 4 programme last week and again this weekend. I was amazed with its apparent lack of balance. However it also amazes me that the argument for the existence of man made global warming, also seems to have the same lack of balance.
I am a complete ignoramus when it comes to science generally; however what I know is that evangelists of any kind turn me off, this issue seem to attract evangelists.
When the politicians get involved, as they have, then the outcomes will only revolve around egos and money anyway. In the end itâ??s the lies and misinformation that will determine our fate both way.
What the Channel 4 programme was successful at doing was to continue the debate, besides what’s wrong with an alternative view. Even if it does have flaws, show me theories that don’t. Misinformation may cause confusion but the whole thing confuses me anyway. If nothing else surly it must demonstrate a need for the “community” to work harder to convince the sceptics, on both sides of the argument.
C4 moved me to look for more information, which lead me to this blog. However reading through the previous 160+ posts I’m still none the wiser. I appreciate this is a complex issue, and far beyond the scope of my intelligence. However I’d like the complex to be made simpler, but not too simple that it misses the point and not sensationalised to the point of incredibility.
It’s hard not to be cynical about people’s motives on both sides of the argument. I can’t help but feel either way it will cost me more in taxes.
Re #167: […it does not matter if the CO2 petered out. Upon cooling, it should have been reabsorbed, then re-released to warm things up again in a classic limit cycle.]
Err… Isn’t that basically what the ice cores and so on show? The planet warms for some reason (most likely Milankovic cycles), that causes some CO2 to come out of its reservoir into the atmosphere, which causes further warming, which continues until the resevoir reaches a new equilibrium. Then something causes enough cooling to push CO2 from atmosphere to reservoir, causing more cooling, which continues until the reservoir is full. But the reservoir has a long time constant…
Re 27: thanks for your blog — the link to the Nature article about warming when the planes stopped flying on 11/9 would be even more knock-down if I could actually read Nature without paying — maybe you could make a brief precis.
How do the climate models stand on contrails? If you take the contrails out from the models which are currently most successful at matching reality, do they respond as the real climate did? It seems this ‘experiment’ can be used to validate the way models match the real world.
Something else on your site got me the answers (RealClimate article on 22 Dec 2004) to a question that’s puzzled me for ages — how we know that the extra CO2 in the atmosphere is anthropogenic. The first way, isotopes, is a bit worrying as I can think of three ways to disturb the isotope concentrations without invoking humanity at all. The bit that can be summed up as ‘we’ve knocked out a lot so it must be our fault’ suggests a wonderful prelapsarian state of balance which doesn’t sound like nature to me at all, but gives me lots of lovely figures to play around with.
JF
Re #169 (Darren): The Discovery of Global Warming on-line book linked in the right bar is the best way to put the current discussion in perspective. IMHO understanding this stuff doesn’t require great intelligence, but it does require some time spent.
What was the source for the aerosol forcing (1940-1970)?
What dissipated it? (i.e. why is it still not there?)
[Response: Industrial activity – mainly power stations and transportation. They haven’t dissipated, though sulphates were reduced in most developed countries through Clean Air Acts in the 1970’s. Aerosols are still a big player, but since they don’t accumulate in the atmosphere like CO2, they don’t grow as fast. – gavin]
What these folk from The Scientific Alliance forget is that while the physical effects of more Carbon Dioxide in the atmosphere – i.e Global Warming – may be disputed, the Physiological and Chemical effects are much more certain. Mankind has altered the air we all breathe, Carbon Dioxide is an acid gas, and it is well attested that the Environment is getting more acid – this may well encourage Virus activity, as this life form prefers more acid conditions. The ‘Flu virus especially being very “pH sensitive”.
Carbon Dioxide is also a stimulant, and is so used in resuscitation apparatus in hospitals. Viewing the way the World is running about like a f*rt in a colander makes one wonder if we are all being over stimulated ?
See the Royal Societies work on effects on the oceans: http://www.royalsoc.ac.uk/news.asp?id=3250
and http://www.bbc.co.uk/dna/actionnetwork/A11109133
BUT
If Nature is intent on removing the “Biological Plague” of Mankind and it’s beasts, through disease, and the other “three horsemen”, then those denying that anything untoward is happening in the atmosphere are helping to ensure that Nature is not hindered overmuch in what it intends to do ?
Can someone address what seems to me to be the obvious objection to the length of the solar cycles-temperature anomaly graph? It doesn’t make sense. What possible connection can there be between these two quantities? The graph makes it worse by connecting the dots with sloped lines that seem to match up with the temperature data. But how can you interpret these lines? Do they represent the average rate of change of the solar cycle length between that cycle and the next? What does that quantity mean?
Please correct me if I’m wrong, but the solar cycle is the length of time from sunspot minimum to sunspot minimum. Is that span of time correlated with sunspot activity? Are there more or less sunspots per unit time in a (marginally) shorter cycle than in a (marginally) longer one? Or is the length mostly independent from the intensity of the cycle? Does this quantity even make sense as a proxy for “solar activity”? Where do you place the “length” of a given period on the time scale? Does the “length” occur at the beginning, middle or end of the period? Or do you line it up so that it best matches the temperature anomaly (presented in a completely different units of a separate y scale!) to “make your point”?
Will someone please page Edward Tufte? Cycle lengths represent spans of time with a distinct beginning and end. Why not plot that data?. I could see someone taking a temperature graph versus time and indicating each cycle as a series of vertical bands indication at what point in time each cycle began and ended. Perhaps varying the shading within each band (low = red for heating v. high = blue for cooling) as the number of sunspots *instantaneously* increases and decreases. Perhaps that might illustrate something — numbers accumulated over the same intervals compare better. If the hypothesis is true, we would see heating when sunspot numbers were low and cooling when they were high. But the graph as presented just seems nonsensical to me and intended to fool people who are easily impressed by statistics.
Am I way off base here?
[Response: Not at all! These are exactly the objections that were raised at the time. However, the desire of the propagators of to show a good correlation to something solar-related overwhelmed their interest in presenting a balanced case. Especially when it was subsequently shown that the smoothing applied varied towards the end with the sole purpose of providing a better fit to the data (See Laut (2003), Damon and Laut (2004)). -gavin]
“Swindled” was almost certainly “unbalanced” in its opinion of the global warming industry. Of course what I hear literally on a daily basis from BBC, NPR and other major media outlets hardly represents a paragon of balance either. Sometimes this science is presented in a manner that would do Leni Riefenstahl proud. In our era I can think of no more unlikely candidates than Mr Gore his cohorts of Beverly Hill’s illuminati to popularize this “dispassionate” search for truth.
I find it unfortunate that I have to remind people who purport to speak for science that motives really don’t matter. I certainly would not attribute any bias on your part with the fact that all of you would be out looking for a private sector job with vastly diminished stature and income if the global warming threat isn’t even a tempest of the teapot variety. Science isn’t concerned with the motives of its spokespeople which more properly belong in the religious and political spheres. I would be prepared to listen to ALL of your arguments in publically open debate. If the lay public aren’t smart enough to figure it all out then democracy and human freedom must take a backseat to this purported exigent threat to the planet.
Therefore, the issue is not whether the editors of “swindled” misrepresented its goals to Carl Wunsch but whether Carl Wunch’s interviewed statements were meritorious.
It appears to me that what one “believes” in the larger sense is more of a religious test than a scientific test. I don’t care if Carl Wunch believes in global warming or the virgin birth. Were his own words accurately represented in the context that they were presented?
Further, would it be possible that appearing in such a film could be career damaging; perhaps a perfunctory denial might then be well considered.
[Response: Carl Wunsch’s career is extremely secure – his comments were made in a particular context – they were used in another to support to position he doesn’t hold. That is misrepresentation, and I think it’s understandable he’s upset. – gavin]
Off-topic, but germane to yesterday’s discussion of the warming from LGM, feedback, etc:
I found almost all of the postings, and all of the replies by Gavin and William, on these matters quite helpful. Thanks to all!
With regard to the increase in methane during this warming, last month’s issue of Scientific American has a provocative article on methane emission by living plants. If confirmed, this would explain the observed methane concentrations in the air above tropical rain forests.
[Response: See Scientists Baffled! – gavin]
#170 James – You are asking the right questions. What causes the CO2 reabsorption and, how long does it take for it to be ready to be re-released? If CO2 release happens progressively with rising temperatures, why should it be reabsorbed at the same temperatures just because they are moving in the opposite direction? What prevents it from being re-released almost as soon as it is reabsorbed?
I could maybe see a big burp of CO2 from mass extinction of plant and animal life in a great heat wave that would then be reabsorbed as species recovered. But, the time constant of that process should be fairly fast and, I’m not aware of any correlation between CO2 concentrations and mass extinctions. If it were an oceans process, why again would it be any different with the temperature coming down than it was with it going up?
RE: Temperature leads CO2 by 800 years in the ice cores
quote: ‘From studying all the available data (not just ice cores), the probable sequence of events at a termination goes something like this. Some (currently unknown) process causes Antarctica and the surrounding ocean to warm. This process also causes CO2 to start rising, about 800 years later. Then CO2 further warms the whole planet, because of its heat-trapping properties. This leads to even further CO2 release. So CO2 during ice ages should be thought of as a “feedback”, much like the feedback that results from putting a microphone too near to a loudspeaker.
In other words, CO2 does not initiate the warmings, but acts as an amplifier once they are underway. From model estimates, CO2 (along with other greenhouse gases CH4 and N2O) causes about half of the full glacial-to-interglacial warming.’
This is where GW falls apart for me, The process that starts the temperature rise is, as above, not understood. At best the C02 is a feedback, so what we are saying is: If we just add c02, without the event that starts the temperature rise, we will get global warming.
While it is worthwhile to look into the past, those scenarios don’t apply to now, so perhaps we should of never quoted the ice cores etc
Re #178, etc. — My rough-n-ready calculation suggests that the increase in atmospheric carbon dioxide concentration during the melting of the LGM ice does not suffice to explain the approximately 6 K warming. I suggest also methane concentrations and albedo effects?
Tziperman, et al., fully referenced in the comments of the ice age trigger thread, have a simple model of glacial-interglracial cycling in which so-called greenhouse gases does not appear: When sufficiently cold, enough sea ice forms to shut off snowfall onto ice sheets. Then the ice sheets shrink until enough sea ice melts, at which time the ice sheets reform. This non-linear model, tuned for orbital forcing, does quite well for the last 900 ky.
Yes. But when the market is horrendously distorted by coercively-financed science, then what gets paid for is science that proves what those who want to coerce more money out of taxpayers want to have proved. If you prove that what is happening can only be solved by coercively destroying the free markets that have created the greatest improvements in the quality of human life, then you’re probably proposing a solution that can, at best, be called “evil.”
I would be tremendously more impressed by the science presented on RealClimate were it not, in the main, coercively funded. Surely there are green philanthropists out there who could finance this science without the stigma of its funding having been coerced from the pockets of taxpayers by governments.
Because the vast majority of CAGW science is politically funded, it will, inevitably, be political science, disclaimers on this site notwithstanding. Until all the scientists who post on RealClimate voluntarily renounce their coercive financing and ask for funding from individuals (perhaps a $2000/per limit, like the politicians have imposed, might be fair) I will be absolutely convinced that their science is political, not factual, not evidential.
#178: Reid, if I understand your question right, then one simplified version of the science might answer it:
Imagine a world at T=260K, CO2=180 ppm, with ocean and atmosphere at equilibrium. Now, change the orbital cycle such that additional forcing leads to a direct T increase of 2K. At 262K, the ocean’s ability to hold carbon decreases. Therefore, it releases CO2. CO2 concentrations rise to 200 ppm.
This increase in CO2 leads to additional warming. T rises to 263K. The increase in temperature leads to an additional CO2 rise, to 210 ppm. This temperature rise leads to more CO2, which leads to more temperature. As long as the series is convergent, you don’t have runaway. To make this easy, let’s say that the final equilibrium state is 264K, and 220 ppm.
Now, new orbital changes lead to direct cooling of 2K. Well, at 262K, we already established that the CO2 equilibrium between atmosphere and ocean would be at 200 ppm. Therefore, the ocean will reabsorb CO2 to reach 200ppm. This will lead to further cooling, which will lead to more CO2 reabsorbed. Until eventually a new equilibrium is reached – or rather, the old equilibrium at T=260K, CO2=180ppm.
This very very simplified model should demonstrate why it seems like the direction of temperature movement matters. “Seems”, because the actual key difference is the orbital parameter: in one case, at 262K and 200ppm the net forcing is positive. In the other, at 262K and 200ppm, the net forcing is negative.
Mind you, with hysterisis effects, you can get results where the direction of temperature change actually does matter, but you don’t need such effects to create a hypothetical system that can have glacial and interglacial states where a CO2 feedback is important in determining the temperature of said states.
(In fact, looking at more of your comments, I think that you are not understanding the role of this external forcing. Maybe this is why you and Gavin are talking at cross-purposes about limit cycles etc.)
It may seem a simple question, but please indulge me. I may ask these questions from time to time just to get to grips with some of the arguments.
If greenhouse gases trap heat from IR, do they also reflect some back? If this is so, is there not a balancing of the two i.e. as the greenhous gases increase the reflection of IR increases, therefore negating the heating effect of greehouse gases?
I am not a skeptic, but I am wavering, as I am sure a lot of people are, especially being rail-roaded down a particular path by a government whom never seem to get the facts right and often mis-represents them(Iraq’s non-existent WMD’s being one). My philosophy at the moment is to err on the side of caution, and in all honesty the UK is becoming a dirty smelly place, so any reduction in the pollutants is a good thing rather than a bad thing.
#170 James – I should have pointed out, though, that this statement appears contradictory, in that it implies that the CO2 has become a negative feedback that pushes itself back into the reservoir:
“Then something causes enough cooling to push CO2 from atmosphere to reservoir, causing more cooling, which continues until the reservoir is full.”
CO2 is always a positive feedback. It will always fight whatever is trying to push the temperature down. If the force pushing the temperature down lets up, the CO2 will immediately start pushing upwards again.
And, that brings me to #179 Joe – Actually, a positive feedback is self-sustaining so, this could theoretically happen. The only plausible scenarios I see are either: 1) CO2 is not a dominant feedback or 2) we are already experiencing a very complex limit cycle which just happens to be limited to a level and a frequency that allows life to exist on the Earth.
#182 Marcus:
Marcus, I’m sorry but, you have made the same mistake as James and converted a positive feedback into a negative one. You have already established that a 200 ppm CO2 concentration in the absence of a forcing will result in a temperature increase to 263K. The CO2 effect is only self-sustaining in the upward direction. To get the temperature down, you have to keep forcing it and, as soon as the force lets up, you will start rising again. That is how a positive feedback works.
Re #184 & #185: Reid — You need to learn about ocean temperature and the effect this has on the balance between atmospheric and deep ocean carbon.
But your point about a complex limit cycle is well taken, IMHO.
#186 David – I need to learn about all sorts of things, and I want to learn others and these two sets only intersect about halfway.:)
I take it you mean that this is a mechanism for limiting the amount of CO2 that can be naturally released into the atmosphere? If so, it does not appear to occur to William in his response to #166.
But, fine, let the CO2 be limited. There is still this nagging problem of how do you get the CO2 back into the reservoir once it has been released and biased the temperatures upwards?
Reid, I’m sorry, but you apparently don’t understand what “positive feedback” means in the climate context, and perhaps this is the key to your confusion. A positive feedback _amplifies_ an external forcing. A negative feedback dampens an external forcing. The _direction_ of said external forcing is not an issue.
So in my example, an external forcing moves us to 262K. In the first case, CO2 is at 180 ppm, the temperature is at 262K. An increase in CO2 (to 200ppm) leads to more forcing, therefore more temperature rise.
In the second case, CO2 is at 220 ppm, and the temperature is at 262K. In order to reach 200 ppm, CO2 concentrations decrease. This leads to less forcing, therefore less temperature.
Think about it. Perhaps try creating a simple spreadsheet model with ocean CO2, atmospheric CO2, an external forcing, and a temperature. If Temp = atm.CO2 + external forcing, OceanCO2 = Aconstant/temp(lag one), and AtmCO2 = Bconstant – OceanCO2, then you have a simple model with positive feedback. Choose your constants so you start in equilibrium (you can always just “run” your model for several periods to find equilibrium). Then increase your external forcing in a step function. There will be an instantaneous temperature change, followed by several periods where atmCO2 and T continue to increase, in ever smaller amounts, approaching a new equilibrium. Decrease your external forcing to its original value, and there will be an instantaneous temp. decrease, followed by atmCO2 and T decreasing back to the first equilibrium.
Then play with your new model to understand its behavior. Try setting the oceanCO2 to be equal to temperature over a constant to see a negative feedback, and damping behavior. Perhaps try an set up a oceanCO2 model that depends on the difference between the previous period atm. and ocean CO2 to determine how fast CO2 enters/exits the system (but still with a dependence on temperature for the equilibrium CO2 level). Or model human CO2 changes by changing the Bconstant in the atmCO2 equation. Its fun! Try it. And you might even learn something despite it being a really, really simple system. =)
#183 Anthony: A key point here is that the wavelength of incoming light and outgoing light are different. Incoming light is high energy (visible, UV, etc.) and is absorbed by the ground. The ground is heated, and emits radiation at lower frequencies (eg, IR).
If you want to get an approximation for the distribution of frequencies, look up “blackbody temperature”, “Planck”, “sun” and “earth” and you’ll probably find webpages devoted to the subject.
However, this isn’t the whole story. For example, black carbon particles which absorb at all wavelengths also serve to heat the earth up. This is because the earth’s albedo non-zero, so black carbon can heat things up by absorbing light that would otherwise have passed through the atmosphere and bounced off a light surface (like ice, or desert) and left the atmosphere without ever interacting with anything…
Re #176: […all of you would be out looking for a private sector job with vastly diminished stature and income…]
You know, before advancing that argument you should really check into the comparative pay rates of the private sector vs academia, especially for those with high-level computer modelling experience. I can’t speak to stature, but I would bet that any of the climate scientists here could get a substantial salary increase, plus nice stock options (which you don’t get in academia), by moving to the private sector.
Reid, plankton. Plenty of info you can find by searching.
Here, for example:
https://www.realclimate.org/index.php?p=134
Google, for example:
http://www.es.ucsc.edu/~silab/biocomplex/activities/BIOPEI_report.pdf
That’s not the same plankton we have now, evolution’s changed the planet a bit since then.
Re #184: [CO2 is always a positive feedback. It will always fight whatever is trying to push the temperature down. If the force pushing the temperature down lets up, the CO2 will immediately start pushing upwards again.]
Not necessarily: I think the key word there is “immediately”. Suppose for instance, that the reservoir is the deep ocean. IIRC, it takes several hundred years for water to make a complete circuit from surface to bottom. (Perhaps someone can provide a better number?) So if the system has stabilized in its warm phase, when a cooling starts, some CO2 will go from atmosphere to surface waters. Some of the surface water (especially the cooler bits) in turn will go into the deep ocean, where it won’t immediately be available to return to the atmosphere in a short warming.
I’m sure reality holds many more complications, but just this simple model gives us a system with two climate states. A large enough external stimulus switches it between states, where it tends to stay until disturbed again.
Also, may I ask you once again to remember that understanding these past climate cycles is not the same as understanding AGW? In the past (at least the last 50 million years of it, since the PETM), the total amount of CO2 in the system changed very slowly. Now humans have increased the CO2 significantly, in a time so short as to be almost instantaneous in geological terms. We’ve taken a smoothly running system and given it a swift kick: is it going to keep on working as before, do something different (which we may not like), or break down completely?
Re #181: [But when the market is horrendously distorted by coercively-financed science, then what gets paid for is science that proves what those who want to coerce more money out of taxpayers want to have proved.]
Fine. Except you’re going to have a real hard time finding someone in the US government (or any other, I think) who actually wants to have global warming proved. Seems to me, in fact, that the current administration has been working pretty hard at denial.
Or even beyond that: why don’t you come up with a few examples of people who actually want AGW? Outside of e.g. religious nuts looking for the Millenium, I don’t think you’ll have much luck.
[If you prove that what is happening can only be solved by coercively destroying the free markets…]
Now where has anyone (other than a few who came in with a pre-existing anti-market bias) suggested that? If you’ll bother to read some of the past discussions related to possible solutions, you’ll find a lot of people pushing market-based approaches. Indeed, you’ll even find some (me, for one) who argue that the fact that fossil fuel users have been exempted from market activity (through being allowed to dump their waste into the commons, without charge) is a significant part of the problem.
owwwwwwwwwww, this hurts… No, no, Marcus. You are making an argument that the feedback is dependent on rate. You are going to have to defend it, if you want to carry on.
Why should the rate of CO2 release be dependent not just on the magnitude of temperature but on its rate of increase or decrease, or more to the point, on its direction of rate of increase or decrease?
Dude… Think… CO2 can trap heat. It cannot reflect it out to space. It cannot funnel it through a wormhole to another region of space or even another universe. CO2 does not dissipate heat. What you are claiming is fanciful, to say the least.
Marcus – CO2 can only trap heat. What mechanism are you proposing for it to dissipate it?
And Marcus, please believe me, if I didn’t know the difference between positive and negative feedback, you would know it. My systems would be falling on your head. A little respect, if you please, whippersnapper. If there appears to be a misunderstanding, it is not on my side. Start from there and, you may learn something.
# 192 James – If there is an existent atmospheric CO2 concentration, does it, independently of other variables, act to increase or decrease temperature? If the forcing has stopped, and there is still CO2 in the atmosphere, will it trap heat or send it out to space? Will it do this immediately, or will it wait a little while inquiries are made as to the state of ocean circulation? What mail service does the CO2 use?
I think what you mean is, will it immediately rebound to its maximum level? But, that is not what I claimed.
I am interested to read all the comments. I enjoyed the entertainment programme, and was disappointed to find that at least one fact presented cannot be verified (I checked the lit. on volcanic CO2). Makes all the rest of the science up for question as well.
But I didn’t find any answer in RC to a couple of important question raised – how many actual practising scientists are in the 2500 IPCC “consensus”? How many have resigned in the manner of the malaria expert, or asked to have their names removed as contributors?
If I missed the information I apologise.
Marcus:
“In order to reach 200 ppm, CO2 concentrations decrease. ”
It doesn’t matter. At 200 ppm, CO2 traps enough heat to cause a rise in temperature. You said so yourself, on the way up. But somehow, you have convinced yourself that it expels heat when the temperature is decreasing. No. CO2 captures heat. It does not capture cold. It cannot work in the way you specify. CO2 will not reinforce a downward trend. It will only, reluctantly, give up heat and smooth a downward trend. This is how positive feedbacks work.
Please think this over and, if you have something more to say, do not couch it in terms like “You do not understand”. If you want to deal with me, have some respect for a guy who has labored in the trenches for decades. You can say “I don’t think I made myself clear” or similar but, the notion that I do not understand feedback systems is something you need to disabuse yourself of tout de suite.
#191 Hank: I responded earlier. If this negative feedback is stronger than the positive feedback of CO2, why would it not be working now? Why would it not absorb the CO2 being produced? Will you claim it just has a slow time constant? If so, and if the cumulative effect is exponential, then aren’t we really at worst looking at a temporary interval of warming to be followed by a return to historical norms ro close to them?