Bishop Hill A marvel and a mystery
Sep 11, 2014 Climate: MetOffice Climate: Models Climate: other A warm welcome to the climate blogosphere for Kate Marvel, a theoretical-turned-climate physicist at the Lawrence Livermore laboratory.
Dr Marvel's new blog can be seen here, and the first couple of posts make fascinating reading. Today's effort is right up my street, considering the empirical evidence for global warming.
[I]ncreased carbon dioxide warms the lower atmosphere (closer to Earth), but cools the upper atmosphere (closer to space). I will probably write more about this later but for right now you'll have to take my word for it (or go here).
Dr Marvel and I are probably on the same page. As a fully accredited lukewarmer, I'm expecting to see some gentle warming in future decades. I'm not really au fait with the theory behind a cooling upper atmosphere, so I'm happy to go along with the idea that we will expect cooling there.
So much for the theory. What is the story on the observations?
[I]s this happening in the observational data? Is the signature of what we're doing evident amidst all the other things the climate system gets up to? To go back to our example: multiple satellite missions have now established that the lower atmosphere is warming while the upper atmosphere is cooling. Not climate models, climate observations. We're pretty sure that this is happening.
Now this is really interesting, because I was recently copied in on some correspondence regarding the empirical evidence for stratospheric cooling. This centred around a graph derived from a recent paper in Nature by David Thompson et al, entitled "The mystery of recent stratospheric temperature trends". The abstract reads as follows:
A new data set of middle- and upper-stratospheric temperatures based on reprocessing of satellite radiances provides a view of stratospheric climate change during the period 1979–2005 that is strikingly different from that provided by earlier data sets. The new data call into question our understanding of observed stratospheric temperature trends and our ability to test simulations of the stratospheric response to emissions of greenhouse gases and ozone-depleting substances. Here we highlight the important issues raised by the new data and suggest how the climate science community can resolve them.
The graph in question looks like this:
;)
The red and blue lines are different empirical estimates of the temperature, while the grey ones are computer model simulations. As you can see, there is a startling difference between the Met Office (in blue) and NOAA (in red). As the paper suggests this is a bit of a problem:
The differences between the NOAA and Met Office global-mean time series shown in Fig. 1 are so large they call into question our fundamental understanding of observed temperature trends in the middle and upper stratosphere.
Moreover, the cooling seems to be associated with the 1991 Pinatubo eruption and its aftermath with stratospheric temperatures if anything rising at other times. So while you could claim that the stratosphere has cooled, you can't claim that you have found any evidence for manmade global warming.
A mystery indeed.
Bishop Hill
Oliver Morton points us to the Met Office's response to the Thompson et al paper. It's too long for me to read right now, but at a glance it's an attempt to reconcile the Met Office's result to NOAA's. This doesn't detract from the main point that there appears to be no significant trend once the volcagenic effect is removed.
Reader Comments (49)
empirical estimates
What is this ?
It's good to see a very slight movement away from model data creation to the more usual measures data but it seems to me that we still have a long way to go before we see the reality or the proof of AGW in the real measured data.
The tone of some of her comments is still sneeringly sarcastic, though.
Yes, the blogosphere needs yet another arrogant reactionary alarmist who seems to have forgotten how to do critical thinking about the time she figured out how to get her grants funded.
Her banal smarmy tone lowers the IQ of her fellow true believers, and that is the last thing a climate obsessed kook needs these days. If climate true believers allow their IQ's to go much lower their autonomic functions might be compromised.
That height is also up in the ozone layer, n'est-ce pas?
An astonishing amount of her post about the non-existent pause consists of ad-homs.
She comes from the Jo Abbess, Mike Mann school of climate science. Lots of Handwavium© and insults.
She speaks of ocean heat content as if supporting data is abundant and its history is long. Seriously!?
Perhaps it's because she thinks Hayhoe is "super-impressive" (eh!?) or that she thinks that climate scientists are "really pretty smart" (I know of some freakin' dumbass ones) or that she actually thinks that we subordinate minions don't understand that the climate system is complex. Really. I already find her tone annoying and I anticipate that her future blog entries will add further to the plethora of logical fallacies she doesn't realise she's already packed into just two blog posts so far.
My hopes are not high. Though I welcome any efforts to expose the lie that models generate scientific evidence, the alternative she seems to favour - short spans of data to draw long-term conclusions - is no less a sin in my eyes.
"Look, sometimes the ocean takes up more heat, and sometimes the atmosphere does. This is because the climate system is complex" says Kate. But how? Why? What mechanism could possibly account for such large changes (maybe there are lots, but she doesn't suggest any). And I thought we were to worry about the air temperature going up 2C, not about the sea temperature going up 0.002C? I'd get bored too, constantly being bothered with the same question that I had no idea how to answer.
She quotes Katherine Hayhoe, that says it all for me.
Just another so called scientist (starting with a very small s) who is pushing the concensus.
The old real Scientists must be truning in their graves.
It is amazing how easy it is to reveal a closed mind.
This lady needs to listen to herself rather than try and put a funky spin on the debate.
My guess is that she has spent some time talking AT very young people and has transferred
that habit onto her blogg.
Not my cup of tea really.
I gather she is another pause denier then; scolding her fellow scientists for imagining that a pause in stratospheric cooling for 19 years and a pause in warming for 17 years is anything that might disrupt the assumption of a dormant mother nature. Then she pulls up a heat content graph that cunningly hides the fact that pre-2003 it was all guesswork and post 2003 there is no detectable warming in the top 700metres and hence no physical way of warming the sea beneath that. Gosh it is indeed so boring - if only it didn't affect quite important things like making sure we have enough energy to avoid freezing and starving the population.
Second paragraph of Conclusions.
“The SSU was not designed to provide climate quality measurements of stratospheric temperature but with careful reprocessing, as described in this paper, temperature trends can be inferred from the measurements.”
So, as I read it, they measure temperatures in the stratosphere by instruments which were never designed to measure temperatures in the stratosphere. Then they adjust the data for a host of errors, which may or may not be errors. And end up with what exactly?
And the science is settled…………
Smug, condescending, contradictory (didn't *they* say our impact overwhelmed 'natural' variation?), evidence-free - WHAT ocean heat content measurements?
As has been noted, there is no significant trend in stratospheric cooling over the last 20 years. A couple of years ago Judith Lean wrote a summary article on climate and solar influences titled 'Cycles and trends in solar irradiance and climate'.
http://www.agci.org/docs/lean.pdf
Figure 4 on page 115 breaks down the atmosphere into Lower Troposphere, Middle Troposphere and Lower Stratosphere. The lowest panel for each shows the anthropogenic influence. As can be seen, over the last 20 years the anthropogenic influence has been flat.
One can therefore assume that carbon dioxide levels are not a dominate influence in this 'fingerprint'. Indeed, in the text Lean writes "stratosphere cooling is actually modeled better by changes in CFCs than by increases in greenhouse gases."
Why doesn't she expose herself to comments? At the moment her 'blog' is just a megaphone into which she can shout at us plebs.
She is also sneeringly irrational. See her post on Ridley's WSJ piece 'I am So Bored With the Hiatus': just juvenile (other comments on this BH thread passim).
She just needs to think back to all the 'snow is a thing of the past' alarmism that we have had from professors and PhDs over the last fifteen years, clearly an act of self-examination that is beyond her.
Not worth a bookmark and quite depressing.
Looking at the other post Kate Marvel has done, she has a graph for 'Increased Heat Absobed by the Earth (10^21J)', the image is credited to K Hayhoe, does anyone know what measure the Heat Absorbed is in, I am not familiar with what J means - I have heard of J notation, if I remember rightly that is something to do with imaginary numbers when using a smith chart / polar chart. Where did this graph originate?. Overall I am not very impressed.
For J look up James Prescott, he of the French pronunciation.
"with careful reprocessing"
Doesn't sound very empirical to me.
As with secondhand cars, 'careful' covers a lot of situations...
Alexej Buergin - thank you seems obvious now. A google search did not even return Joule when I asked what the figure J was.
"My favourite planet in the entire universe..."
How old is this climate "scientist"? 12?
I never cease to be amazed at how supposedly intelligent people can lack basic reasoning skills.
The pause isn't boring. It defies the predictions. It's interesting to people who are intellectually curious, and boring to ideologues.
The heat is in the ocean, she says, though we can't measure it.
She would be embarassed if she had any self awareness.
Any further comments which aren't about the subject of stratospheric temperature trends will be snipped.
How do radiosonde numbers compare to the satellites? At altitudes where a comparison can be made we'd have a way to look further back if we could correlate them.
I've been lurking here for a year or so, generally appreciative of the tone of the posts in a field that seems to be often full of ad-hom attacks. I've started to go more in depth on both sides of the debate and find the views and comments here to be very helpful. For example getting into the data that caused the furore discussed in this post, http://www.bishop-hill.net/blog/2014/8/21/oi-lord-stern-your-boy-took-one-hell-of-a-beating.html, was quite entertaining.
Probably about time I made a comment or two myself.
I've spent 20 minutes trying to find the source of the graph she posts (possibly Nuccitelli et al., 2012?) and a description of the source data for it.
@JamesG - could you point me to the location? If it's the case that only post-2003 is actual data, I'd find that disappointing.
Also, controversially, I actually enjoyed Dr Marvel's writing style, it made me smile. Just saying.
Bish
This comment is not specifically on tropospheric cooling but having visited Kate's blog earlier today I was disappointed that there was no facility to comment. The point I wanted to make is that her analogy to the detective is both good and bad. Let me expand.
Under the criminal justice system it is the duty of the 'detective' to look for likely suspects and build a case. (It is only in Hollywood that the notion of the detective searching for the 'truth' holds any sway.) So the police build a case and if it is strong enough it is prosecuted by the relevant authorities through the courts. This is, of necessity, an adversarial approach to solving crime.
The position of a scientist, on the other hand, (and here I am obviously talking of the true scientist) is to set up a thesis and then set out to invalidate it. The very opposite of what plod does. Hence the bad analogy.
Where the analogy works really well (but I suspect this is lost on Kate) is that climate science has adopted the adversarial approach of the criminal justice system. They looked around for a likely perp. CO2 had guilt written all over it and so they set out to make their case. In short they did not do science.
So what I would like to ask Detective Marvel to do is to re-examine the case and point out all the reasons why CO2 might not be guilty.
And there is a further point, but to make it I have to revert to the Detective Marvel approach. She implies that 'we' are somehow responsible for 'increased carbon dioxide'. That may be the case but to secure a conviction she is going to have to prove not only that CO2 pulled the trigger but that the CO2 in question was emitted from 'our' 4x4's and power stations. As we non-scientist true sceptics are only too aware there are a number of issues that our star witness Dr Murry Salby will be only too pleased to address.
bbbut muh tropospheric hot spot!
trial balloon- trying humor cuz it works for marc morano.
" you have to connect with humor. It’s ironic, but he’s been very successful, and I thought, okay, I could learn from him."
(see http://thinkprogress.org/culture/2014/09/10/3565769/merchants-of-doubt-director-deception-climate-change/ )
cuz this doesn't cut it: http://www.youtube.com/watch?v=LiYZxOlCN10
cook's consensus is the best they've got going, but http://thinkprogress.org/wp-content/uploads/2014/09/luckies-972x674.jpg
Dr. Marvel seems to be into a new phase of 'where's the heat'. In this iteration, the heat is irrelevant because the CO2 is cooling the upper atmosphere.
Of course no discussion by the excellent lady regarding the missing tropospheric hotspot. No disclosure that ocean heat content is not in fact behaving as it would need to. No discussion of the admitted failure of the models.
I do wonder if she was this snarky and content free when her colleagues were trashing Dr. Pielke, Sr. for suggesting that OHC was the proper place to look for AGW?
Her link above to why CO2 allegedly cools the stratosphere [which is also the same webpage that RealClimate/Gavin links to for an explanation] states
"In the stratosphere, this emission of heat becomes larger than the energy received from below by absorption and, as a result, there is a net energy loss from the stratosphere and a resulting cooling."
So, how does CO2 emit more than it absorbs in the stratosphere?
http://hockeyschtick.blogspot.com/2014/09/oh-irony-cutting-co2-emissions-is.html
Is she saying that there's now conclusive satellite evidence for the 'tropospheric hot spot', or is it no longer seen as evidence of AGW?
I'll note that not all Lawrence Livermore physicists would agree with her, especially Lowell Wood!
Any sensible discussion of cooling in the stratosphere must start by recognizing that at least TWO mechanisms have been proposed: 1) Destruction of ozone by CFCs and related sources of chlorine and bromine atoms. The stratosphere is warmer than the tropopause immediately below because ozone at this altitude absorbs Incoming solar UV. 2) Increased CO2 at this altitude causes both absorption and increased radiative cooling. In the stratosphere, increased radiative cooling wins because the more of the radiation being absorbed was emitted where it is cooler than the stratosphere. In the troposphere, the opposite is generally true. A GCM with a stratospheric chemistry module (probably present in all major models these days) include both mechanisms, but the parameters used by chemistry modules don't all come from well-controlled laboratory experiments where concentrations can be reproducibly varied. The springtime Antarctic hole is mediated by polar stratosphere clouds (ice crystals).
The spike associated Mt. Pinatubo could come from a number of factors. Most likely the aerosol that reach the stratosphere both reflect and absorb incoming SWR, thereby heating the stratosphere and cooling below.
Kate writes: "No serious scientist truly believes that the slowdown in surface warming invalidates greenhouse physics." Neither does Matt Ridley, the author of the WSJ's "nonsense", or any other lukewarmer. Give her the "Strawman of the Year" award. The slowdown in warming cast doubt about the ability of climate models to properly reproduce climate sensitivity and/or unforced variability, not the GHE.
Furthermore, Kate also doesn't tell us that the heat accumulating in the deep ocean won't return to the surface for centuries, if not millennia, imposing no quantifiable harm. Neither she, nor anyone else, shows us a comparison between heat observed to be accumulating in the ocean (especially during the Argo era) and heat predicted by GCM to be accumulating. Trenberth lowered his estimate of the radiation imbalance by 1/3 after ARGO, a reasonable estimate of the discrepancy.
The MSU temperature data shows the pause.
The troposphere moisture content data shows the pause.
Now there is reason to believe the stratosphere data shows the pause.
The truly tedious part is trying to get these people to explain how greenhouse gases which were supposed to increase the heat in the troposphere and subsequently warm the surface, has managed to bypass all that "process" and deposit the heat directly into the deep oceans. Maybe it's one of those internet technology things like how you can now deposit a check by just taking a picture of it with your phone.
An aside: Imagine if you will a journey into the past where you have to explain to a random stranger the phrase "deposit a check by taking a picture of it with you phone",
Sep 11, 2014 at 3:44 PM | Unregistered CommenterH2O: the miracle molecule
How very well expressed.
Yes, the job of the police detective is to find information that will secure a conviction - not to discover who else might also have committed the crime. Nor to uncover all the facts that could exonerate the principal suspect. Climate science's quest has been for evidence of the guilt of man-made CO₂.
In the case of CO₂, however, climate "science" (in the form of the IPCC) has also played the role of the judge and the jury too. Hardly surprising that the conviction was announced without bothering to call any witnesses for the Defence. in fact, there was no Defence.
There are two aspects of the case for the Prosecution:
- The increase in atmospheric CO₂ is unprecedented and is caused by humans.
- The increased atmospheric CO₂ will cause/is causing dangerous climate change.
The investigation of the first aspect seems to have halted as soon as some purely circumstantial evidence was found leaving it to one loan computer scientist (Gavin Cawley of UEA) doggedly to search for definite evidence.
Sep 11, 2014 at 3:44 PM | Unregistered CommenterH2O: the miracle molecule
How very well expressed.
Yes, the job of the police detective is to find information that will secure a conviction - not to discover who else might also have committed the crime. Nor to uncover all the facts that could exonerate the principal suspect. Climate science's quest has been for evidence of the guilt of man-made CO₂.
In the case of CO₂, however, climate "science" (in the form of the IPCC) has also played the role of the judge and the jury
too. Hardly surprising that the conviction was announced without bothering to call any witnesses for the Defence.inIn fact, there was no Defence.There are two aspects of the case for the Prosecution:
- The increase in atmospheric CO₂ is unprecedented and is caused by humans.
- The increased atmospheric CO₂ will cause/is causing dangerous climate change.
The investigation of the first aspect seems to have halted as soon as some purely circumstantial evidence was found, leaving it to one
loanlonecomputer scientist (Gavin Cawley of UEA) doggedly to search for definite evidence.Thanks mum.
I've deleted a whole lot of comments that were not even slightly on topic.
Martin's Mum wrote: "Yes, the job of the police detective is to find information that will secure a conviction - not to discover who else might also have committed the crime. Nor to uncover all the facts that could exonerate the principal suspect."
You got that wrong - most defendant don't have the resources to uncover the facts that could exonerate the principal suspect, ie them. A responsible prosecutor needs to assess the defense's case before he choses to prosecute. What do you do when new information you should have known about emerges years after conviction?
In the case of climate change, "defense scientists" have systematically been denied access to the funding and courtroom (the IPCC and journals) and the jury.
Bish, on the stratosphere/troposphere thing, it's pretty easy to understand without the physics equations.
GHG trap heat by radiation scattering. They absorb and re-emit photons of IR. By the rules of quantum physics, emit in any direction, mostly NOT up toward the stratosphere. An analogy (although completely different mechanism) is a lightntrapping fog reflective scattering). IR can only escape from the top of the GHG 'fog bank', which is always below the tropopause almost by definition. The stratosphere is always radiating its heat to space. If less comes up from below because 'trapped' warming the troposphere, then the stratosphere must cool at the same volume and temperature (IR frequency/energy) adjusted rate. Just another consequence of the transitory radiation energy imbalance called AGW.
Wrote an essay about it for the upcoming book, because there is so much confusion. Explains why the doubling thing is logarithmic (more CO2 having less effect), and why the non-lukewarmer skeptic saturation thing is wrong. The 'fod is saturated, but there will be more of it. The top of the 'fog' rises with rising CO2 and causes more trapping, but with a colder (less energy per IR photon) partly countered by a larger top surface from the Euclidean geometry surface of sphere as function of radius first proved by Archimedes. All good fun with no equations.
@Rud Istavan
If you have layers of the atmosphere that absorb all the IR of the wavelength absorbed by the greenhouse gas and emit it, 50% up(ish) and 50% down(ish) then its like having a fog that only scatters 50% of the radiation back down no matter what the concentration is. I presume that you are saying that there will be 200 rather than 100 such layers if the concentration of the greenhouse gas doubles, so that the portion of surface emitted radiation that reaches high altitudes is 10(-60) rather than 10(-30). Ditto for IR emitted towards the surface from the upper atmosphere.
In the real atmosphere, the energy absorbed is shared with the more numerous poor emitting gas molecules and the air rises. It cools at .1 degree per 15 metres becoming even less likely to emit that energy as downwelling before it rises further. Effectively, this makes your fog scatter less than 50% of the IR light directed upwards and more than 50% that is directed downwards.
How can the upper atmosphere possibly have a noticeable effect on the surface?
Bish, delete if you must ... but ... as others have noted, Dr. Marvel's public perorations are somewhat less than impressive - as is her rather scant publication record (3 papers), assuming her LinkedIn Profile can be believed.
Here's her academic record:
Further, her knowledge of climate change/global warming does not appear to have been acquired via her climb up the academic ladder, but (IMHO) considering her enchantment with "fingerprints" - a well-known Ben Santerism to which she gives no less than seven mentions (excluding her choice of title) in her Sept. 10 "Sayings" - more likely acquired via proximity to Santer during her Livermore years (Nov. 2011 to present), during which time she presumably became a Climate Scientist™
Although it is within the realm of possibility that Marvel acquired her climate science knowledge and expertise during a 2-month Post-Doc stint at Stanford's Carnegie Institution for Science, Department of Global Ecology** - immediately prior to joining Team Santer (about which, readers will recall Bernie Lewin's series of essays Madrid 1995: Was this the Tipping Point in the Corruption of Climate Science?)
So Marvel may well be a "Physicist-turned-climate scientist with substantial math and computing experience [whose] Specialties [include] Climate change and energy, programming and open-source software development, complex network analysis, statistical physics, international policy" as claimed in her LinkedIn Profile.
But I, for one, am far from convinced that Marvel's contributions to date (via her blog or elsewhere) - to "climate change and energy" - are particularly noteworthy. Although I would willingly concede that perhaps she is a dedicated Santerite who sees herself as another little Mann-in-the-Making. IOW, one who feels duty-bound to direct sneers 'n smears at all who do not accord with (in this instance) Santer's view of the world as it should be unfolding;-)
** Department Founding Director, Chris Field, IPCC's AR5, WGII Co-Chair, who not too long ago teamed up with WMO's Michel <There. Is. No. Pause> Jarraud.
Rud Istvan
Spare us the essay, please - the first four sentences here disqualify you on this subject:
1. GHG trap heat by radiation scattering.
[No they don't - scattering is a process that does not involve absorption and preserves the wavelength of the scattered radiation. 'Trap' makes no sense.]
2. They absorb and re-emit photons of IR.
[1. and 2. cannot both be true. If 'IR' is absorbed, then what is evenutally emitted is much lower frequency than 'IR'.]
3. By the rules of quantum physics, emit in any direction, mostly NOT up toward the stratosphere.
[Which 'rule' would this be? How does a GHG molecule know what is 'up' and what is 'down'?]
4. An analogy (although completely different mechanism) is a lightntrapping fog reflective scattering)
[lighttrapping OR reflective OR scattering... which is it going to be? The analogy is nonsense.]
No-one on this thread appears to have factored in the simple fact that the emissivity and absorptivity of a GHG IR band falls with concentration below the self-absorption threshold. I suspect the models assume that emissivity/absorptivity is constant.
In an attempt to answer my previous question (Sep 11, 2014 at 5:30 PM), I came across this site...
http://www.remss.com/research/climate
...which shows that although stratospheric temperatures suggest some human influence, tropospheric temperatures still appear to be 'misbehaving' with respect to model predictions.
I wonder if Dr Marvel is aware of this?
Dr. Marvel's understanding of criminal detection makes her a candidate to play the next Inspector Clouseau.
Kate might watch this classic scene and ponder that getting the basic facts right is not so helpful if one is blinded by one's preconceptions:
https://www.youtube.com/watch?v=SXn2QVipK2o
Dave
Judge for yourself how much is guesswork and how much can be relied upon by reeding about the origin, biases, sparsity and crudeness of the pre-Argo data in these two papers:
http://rhinohide.org/climate/publications/Gouretski/NearSurfaceOceanWarming1900.pdf
http://ocean.mit.edu/~cwunsch/papersonline/wunsch&heimbach_jpo2014_bidecadalheat.pdf
Incidentally I found that graphic here: http://wwwf.imperial.ac.uk/blog/climate-at-imperial/
which implies it is from the IPCC 2013 report though I never saw it there...
I have several times seen the claim that an increase in the concentration of GHGs should increase temperatures in the lower atmosphere but reduce them in the upper atmosphere, but I have never seen any clear explanation for the latter alleged reduction. Of course, if we inject increased quantities of, say, CO2 into the atmosphere, there should be a *temporary* cooling of the upper atmosphere, because following the injection the solar heat being radiated or reflected from the surface of the earth will take longer to 'escape' from the lower atmosphere. But this would surely be only a short-term cooling, as a new equilibrium will soon be reached. In equilibrium, every part of the atmosphere must (on average) be radiating as much heat as it absorbs, otherwise its temperature would increase without limit. (Which is incidentally why it is misleading to talk about heat being *trapped*, rather than just impeded, by GHGs.) To give an analogy, suppose we put a semi-permeable membrane, such as a fine-meshed net, across the course of a flowing stream. The short term effect will be that water backs up behind the net, while the flow downstream from the net will be reduced. But as the water backs up, the pressure against the net will increase, and more water will flow through, until the flow downstream of the net is equal to the inflow from the source. The water level upstream of the net will be permanently increased, but downstream of the net it will (other things being equal) be restored to its former level, since the same amount of water per unit time is flowing through the channel as before. Am I wrong about this? And if I am not, where does the analogy with the effect of GHGs break down?
David, Bish and others interested in stratosphere cooling by increasing CO2: There are several ways to understand why this happens:
SInce convection is unimportant in the stratosphere, heat transfer occurs by radiation. The 2 LoT ensures that radiative heat transfer will be from hotter to colder. Since there is little water vapor in the stratosphere, CO2 is the main GHG that mediates radiative heat transfer by emission and absorption. When CO2 increases, the rate of heat transfer increases. Some altitudes in the stratosphere are warmer (up to 270 degK) than others, because this is where most solar UV is absorbed by O2 and O3. Increased radiative heat transfer mediated by CO2 between these warmer altitudes and cooler locations causes the warmer altitudes in the stratosphere to cool and those cooler locations (including the tropopause and space) to warm.
One can get into the technical details about what happens at every wavelength and altitude: absorption (heating rate) proportional to n*o*I_0 and emission (radiative cooling rate) proportional to n*o*B(lamba,T), where n is the density of CO2 (or other GHG, o (sigma) is the absorption cross-section at the wavelength of interest, I_0 is the intensity of incoming radiation, and B(lamba.T) is the Planck function for wavelength of interest and the temperature of the emitting gas. The probability that a photon isn't absorbed as it travels between two altitudes doesn't depend on the direction of travel. So net heat transfer is proportional to n*o*[I_0 - B(lamba,T)]. When a particular altitude is warmer than the average location it absorbs photons from, B(lamba,T) is greater than I_0 and increasing CO2 (n) speeds up transfer. When CO2 (n) increases, the distance over which the average photon transmits heat does get shorter, but that heat transfer is still from hotter to colder.
The same considerations applies to the troposphere. More radiation is traveling upward (towards space) than downward and it was emitted where it is warmer, making I_0 greater than B(lamba,T). And when the temperature of the emitting and absorbing locations is the same, I_0 equals B(lamba,T) and no heat transfer occurs. I_0 = B(lamba,T), meaning that the radiation has blackbody intensity; that emission and absorption are in equilibrium.
Thanks. As a layman that's a bit more 'advanced' than I was hoping for! But would I be right to say that the stratospheric cooling effect is not a consequence of the general properties of GHGs, but of the particular balance of different gases, and particular types of radiation, at different levels in the Earth's atmosphere? So that for example in an atmosphere consisting entirely of CO2 we might not (and as far as I can see, would not) see the same effect? Could we explain it for the layman more crudely as something like this?
- oxygen (O2 and O3) in the stratosphere is heated by solar UV light, but O2 and O3 are relatively bad at radiating that heat away.
- In contrast, CO2 is good at radiating heat away (as infra-red).
- CO2 in the stratosphere picks up heat from O2 and O3 (by contact?) and radiates it in all directions (including to the troposphere and out to space).
- Increasing the proportion of CO2 in the stratosphere would speed up this process and thereby keep the stratosphere (or certain levels of it) cooler than they would otherwise be.
If it is something like this, I think at least qualitatively I can understand it. What I found puzzling in what I had seen before was that it seemed to be implied that a warming of the lower atmosphere led almost necessarily to cooling of the upper atmosphere, and I could not see why this should be the case except as a temporary out-of-equilibrium effect.
If you take a look at this diagram:
http://jonova.s3.amazonaws.com/graphs/co2-absorption/nimbus-satellite-emissions-infra-red-earth-petty-6-6.jpg
you might see what it’s all about.
CO2 blocks the 15μm band so tightly and thoroughly, meaning it absorbs so completely within that wavelength segment, that hardly any IR-radiation being emitted from the surface or from inside the troposphere within that band is able to escape to space before it’s reabsorbed. Only at and above the tropopause will this happen. This is why CO2′s effective contribution to Earth’s total IR flux to space comes from the uppermost part of the troposphere.
WV, on the other hand, is not such a complete absorber, but instead absorbs and emits across a much wider spectrum of wavelengths than CO2. So some IR from within those bands are always able to escape to space even from the lower parts of the troposphere, although most even here is emitted from the upper parts.
So when we see that Earth’s IR to space is emitted up through the entire tropospheric column, this is from WV and clouds and the bands that they cover, NOT from CO2.
CO2 only emits to space from tropopause height and stratosphere. Most of Earth’s total IR flux to space, however, is emitted directly from the surface or from H2O (WV, cloud tops) all the way up through the tropospheric column, mainly from the upper part.
However, it’s the convective processes from the surface that determine how much energy that is ultimately to be radiated to space. It’s got nothing to do with the temperature of the specific air layer that’s going to radiate it, as the ‘climate estbalishment’ wants us to believe. Convection is simply the process by which energy from the surface (and the Sun) is brought up to where it can be radiated back to space (from whatever level). If convection brings less energy up, then less IR will be emitted to space. And vice versa. It’s that simple. We see this very clearly in the OLR data. For instance, warm ENSO events bring lots of deep moist convection, moistening and hence warming the troposphere. And OLR through the ToA shoots up. Cool ENSO events hold convection back, the troposphere dries and cools. And the OLR drops.
What controls total OLR through the ToA on Earth, then, is basically the water cycle’s response to surface processes, mainly ENSO. OLR is very much correlated to the ENSO process, specifically to surface temps > tropospheric temps, modulated mostly by clouds.
There is no observational evidence whatsoever from the real world that more CO2 in the atmosphere could and does raise a postulated ‘effective emission height’ in the troposphere. The tropopause will lift if the troposphere warms. And with a warming troposphere, MORE IR will be emitted to space, not less. This is what we see in the OLR data over the last 30+ years.
What we DON’T see anywhere in the data is the tropopause lifting FIRST and THEN the troposphere warms. The causal chain moves UP, not DOWN.
Interesting post Kristian. Is there any more information on this hypothesised process? Intuitively to me I would think convection/water cycle would be the dominant controlling process.
Kristian says
This leads to a paradox. In a warm ENSO event, whilst there is a short term increase in surface T, the earth system is cooling (greater OLR) and in cool ENSO, whilst there is a short term decrease in surface T, the earth system is warming (less OLR). Perhaps better seen as a system that charges and discharges energy over a given cycle with the heat capacity of the oceans acting as the battery.
Rob Burton
you may find this link helpful - http://www.drroyspencer.com/2014/09/water-vapor-feedback-and-the-global-warming-pause/
you will note that Kristian comments on that thread - but I think you need to keep your critical facilities on high alert in reading some of the other comments there.