Last week, a Norwegian official-looking – and in my view – climatesceptic website praised Eigil Friis-Christensen from the Danish space center (featuring in the Great Global Warming Swindle) and hailed him for having given the best speech ever in the annual Birkeland seminar organized by Norwegian Academy of Science and Letters (NASL). There were rumours of controversy behind the scene before the seminar, as the NASL is regarded as a prestigious body in Norway.
Furthermore, Svensmark and Friis-Christensen have written a response (title ‘Reply to Lockwood and Fröhlich – The persistent role of the Sun in climate forcing’; DNSC Scientific Report Series 3/2007) to a recent paper by Lockwood and Frohlich (LF2007). In this response, they state ’… [LF2007] argue that this historical link between the Sun and climate came to an end about 20 years ago‘. Another quote from their response is ‘Here we rebut their argument comprehensively’. So the cosmic ray theory isn’t quite dead after all?
There are several earlier posts here on RC that provide a background to the story about the galactic cosmic rays (GCR) and our climate (here, here, here, here). There is still no long-term trend in the GCR, not even in the Svensmark and Friis-Christensen’s response (see also figure below). This seems to be acknowledged now.
The LF2007 paper and the response focus on just the last 2-3 decades for which there were direct measurements of the total solar irradiance (TSI= solar energy summed over all wavelength), but if they had read my paper on this issue in GRL 2005, they would have seen that there has not been any trend in solar activity or GCR since 1952 (also seen in the figure below).
In addition, there is no evidence of any long-term trend in the low cloud cover (IPCC AR4), and the GCR-hypothesis has a problem with explaining the trend in the diurnal cycle, enhanced warming in the Arctic and a cooling in the stratosphere. The only explanation we can offer is an enhanced greenhouse effect.
It may be of interest for historians that the story about the GCR has been a long-winded epic (total cloud cover, low clouds, adjustment of ISCCP cloud data, etc.), and now new characters are thrown onto the stage: radiosonde measurements (HadAT2) representing the tropospheric temperatures and data from a ‘simple’ ocean data assimilation (SODA).
SF2007 argue that: ‘When the response of the climate system to the solar cycle is apparent in the troposphere and ocean, but not in the global surface temperature, one can only wonder about the quality of the surface temperature record’. This is a rhetorical question, and not a very scientific one. For starters, one cannot exclude the possibility that near-surface processes dominate at lower altitudes thus degrading any correlation. But, in the mind of Svensmark and Friis-Christensen, it is perhaps the GCR that is the most dominant driver.
Svensmark and Friis-Christensen do not disclose the geographical coverage of the ocean temperature they use to correlate with GCR, but the strong annual cycle and inter-annual variations are typical characteristics of local observations rather than global fluctuations. Note, the global surface temperature includes the world oceans (~70%) of the surface.
Another interesting aspect is the improved correlation with altitude. This is not what one would expect to see if the GCR mechanism played a key role, as changes in cloudiness would affect the planetary albedo, and hence the solar energy absorbed by the surface. The troposphere would then respond to the surface changes.
A more likely explanation could be that changes in UV associated with the solar cycle affects the stratosphere (a little disputed hypothesis), and that the signal then propagates down into the troposphere. Thus, we cannot rule out that solar activity influences our climate in ways that do not involve GCR and clouds.
The physical link between any ultra-small particles and much larger the cloud condensation nuclei is still lacking, even after the experiment performed in Copenhagen. Thus, the hypothesis is still speculative. The GHG-effect, on the other hand, is well-established.
According to the official looking Norwegian climatesceptic website, Friis-Christensen states that his work has been controversial, but mainly because of political and not scientific reasons. The fact that he and Svensmark now offer a response to LF2007 seems to contradict his own belief.
Svensmark and Friis-Christensen object to LF2007 by stating ‘Lockwood and Frohlich erase the solar cycle from various data sets by using running means of 9 to 13 years’. It is interesting to note that Svensmark and Friis-Christensen now acknowledge the fact that filtering time series can produce misleading impression after the dubious curve-fitting magic in the famous Friis-Christensen & Lassen (1991) science paper.
Svensmark and Friis-Christensen further argue ‘In any case, the most recent global temperature trend is close to zero’. This is not true, as the IPCC AR4 highlights. I think the the statements in their response ‘use of a long running mean creates the illusion that the temperatures are still rising rapidly early in the 21st Century’ and ‘global surface temperatures have been roughly flat since 1998’ are dishonest (see figure above ).
Svensmark and Friis-Christensen should know of the chaotic nature of our climate system and the fact that it takes more than a few years to determine whether there is a trend or a pause in the trend. The most convincing explanation is that there are also many factors (such as aerosols) playing a role, adding to inter-annual and inter-decadal variations.
It is worrying that the director of the Danish space center makes such misleading claims and then receives honours in Norway by NASL. The controversy running up to the event was therefore understandable, even though Friis-Christensen was supposed to talk about geomagnetism rather than climate.
To answer the question I posed in the beginning of this post, I think that the chapter on the connection between GCR and clouds is not yet closed, but all the evidence goes against the notion that GCR are the cause of the present global warming.
Re # 89 Rod B’s comments about evolution
Sort of OT, but linked by the importance of mechanisms, perhaps. Rod, Darwin (and Wallace) didn’t come up with a theory of evolution, but rather a theory of evolution through natural selection. Let’s accept that perhaps 99+% of mutations are “for the worse.” Surviving species don’t reflect this trend because natural selection weeds out mutations that don’t lead to increased fitness, i.e., more descendants. BTW, the singular form of “species” is “species.”
Chris (87), I didn’t thoroughly read all references (especially the one in Norwegian [;-) but I think it’s safe to deduce that Svensmark and Friis-Christensen do provide evidence for a contribution of CRF to the Earth’s “climate”. I can’t assess the veracity of the evidence, though, and my gut feel is that the GCR-climate connection is very tenuous; that’s why I’m asking my questions. I answered (partially) your “off-topic” queries in a subsequent post.
James (92) said: “…Suppose for the sake of argument that evolution or standard AGW theory do have some holes. That doesn’t translate to support for competing conjectures, or fill in their holes….” Of course not. I never said so. I never said I do not subscribe to evolution theory. I just said it has holes, as do lots of stuff. But it is the frenzied reaction to that last statement that is the interesting/telling part.
You then ask, “Where’d the intelligent designer come from?” I don’t have a clue. Where did the primordial singularity come from? Maybe everything’s just kinda always been there, ala Fred Hoyle.
Harmon, very helpful post (93). Thanks.
ps to earlier post. I’d better hold off a little on accolades for your post, Harmon. There seems to be a fuss about…..
Rod B. OK, I know I risk going seriously off topic, but when “intelligent design” gets thrown out as a “scientific” theory, it needs to be pointed out that not only is it not scientific, it never can be scientific. The reason is that every development is conditional on the “will” of a designer, so you have a theory with an unlimited number of adjustable parameters. Rod, you need to go here:
http://www.talkorigins.org/
Likewise, science is basically conservative. If you have a theory that works (e.g. anthropogenic causation of the current warming epoch), you don’t toss it out for something totally different. If possible, you build on it, add to it. If GCR were to have an effect, first, there would have to be a physical mechanism (so far there is not). Second, they would have to explain not just how the GCR work, but also why CO2 is much less effective than all the evidence to date has indicated.
Rod, BTW, the mechanism S & F-C are talking about modulates GCR fluxes by changing the heliomagnetic field. We know that GCR fluxes do change significantly with the solar cycle. There’s no evidence of any other systematic trend.
Timothy,
Yes, the energy goes to other molecules, collisionally, which also emit a negligible amount of radiation, just like the original CO2. In fact, since most of them are homonuclear diatomics, N2, O2, they pretty much don’t emit from their vibrational states at all.
Obviously, you don’t like to talk about lifetimes of excited states. You prefer rates of emission, whoops, that also has a time component, doesn’t it?
When speaking of emission, do be certain that you are addressing spontaneous emission, which is isotropic, not stimulated emission, which is by far nearly all of the emission from the gas phase in the radiation field of a bb, and is coherent with the exciting radiation. Of course, stimulated emission falls out naturally with observed net absorption. You can ignore spontaneous emission of the gas at STP, it’s pretty much not relevant in vibrational bands.
Yes, a certain, very small, percentage of molecules will emit at a given rate (there’s that pesky time reference again).
By the way, Goody and Yung do in fact depend on a simultaneous radiative and collisional equilibrium to substantiate the claim that the source function for CO2 emission is the Planck function. This is done by setting the net absorption to zero, and setting the state populations to the Boltzman distribution. Solve the equation yourself, the spontaneous emission is large. If the radiative equilibrium were real at STP, I would be accepting the GHG theory right now.
Those who are interested, read the first part of chapter two in Goody and Yung. Hank you have the right book listed.
I’d provide the calculation, but it is currently in the margin of my first PChem book. That’d be Atkins. There’s only a page or two on this topic in Atkins, and it uses different notation, but you can see the same thing in chapter two of Goody – just with very different conclusions.
I’ll eventually throw some of this into Excel, and if I get that far, I’d be happy to share it with you. Most of my musings end up as hand written notes all over the pages of textbooks, but lest you think it too disorganized, feel free to take a pencil and go through the equation yourself.
Harmon (#93) writes:
Physics isn’t a schmorgesborg – but the fact that you seem to think so would seem to help explain how you arrive at your conclusions. “Stefan’s law” for blackbody radiation is something that was first discovered in relation to realistic bodies – where the emissivity varies according to the wavelength. Black bodies (where the emissivity is equal to 1 for all wavelengths) and grey bodies (where the emissivity is a constant at all wavelengths but less than 1) are a fiction, albeit each a useful one for grasping the physics involved. And a spectral emissivity is strictly applicable to greenhouse gases – although it tends to be rather quantized – a bit more so than crystals.
Harmon (#93) writes:
Excitance? Now this is getting exciting! But there is this talk about mix and match. Makes me nervous.
Numerous problems. Let’s hit just a couple.
First, you seem to be thinking of emissivity as a single constant. Grey body approach – rather than spectral emissivity. Which might help to explain why you have a problem with Stefan’s law – the way in which Stefan’s law is generalized in physics is with a spectral emissivity where the emissivity differs according to the wavelength – something physicists have been aware of from the start.
Assuming that emissivity has to be constant, you seem to have “naturally concluded” that the emissivity of gases has to be low. However, assuming that this is what you were thinking, I am still puzzled as to why you think that gases will absorb without emitting. The emissivity and opacity are the same – and the terms are typically used interchangeably.
This I believe is why you later state:
But the spectral emissivity will often be quite close to one for certain parts of the spectra for a given greenhouse gas such that the gas will become entirely opaque at given wavelengths. That’s why we will talk about certain wavelengths or bands becoming “saturated,” although there will be neighboring regions, called the “wings,” which are not saturated. The higher the concentration of gas, the broader the band which becomes opaque.
… and actually this pretty much takes care of your “analysis of emissivity” of greenhouse gases, I think.
Now what is this about radiative equilibrium? Thermal equilibrium?
In the study of the physics of the greenhouse effect, we don’t assume radiative equilibrium or thermal equilibrium. Normally we will speak of a local thermodynamic equilibrium – but note the “local.” Local is all that is required for Kirchoff’s law to apply. In a local thermodynamic equilibrium, temperatures can be different at different places.
Given the nature of the local thermodynamic equilibrium, the emission will typically exceed the absorption, that is, for most of the relevant parts of the spectra. Why? Principally because of moist air convection. The thermal energy which gets emitted by greenhouse gases doesn’t care where it comes from – its kind of like that American ideal. But as such, greenhouse gases will typically have the direct net effect of cooling the atmosphere – but due to their backradiation (“downwelling” radiation which reaches the surface), will warm the surface, resulting in more moist air convection, thus indirectly warming the atmosphere by means of the additional moist air convection.
Harmon (#93) writes:
You state, “If the atmosphere is heated by the absorption of IR photons…” Greenhouse gases tend to emit more radiation than they absorb, not less. And the direct effect is to cool the atmosphere – but this warms the surface. See directly above.
You state, “Remember that energy is conserved.”
Good point – if you know how to apply it.
The climate system as a whole (including the surface and the atmosphere) cannot get rid of energy by means of convection or conduction. In fact there is only one way – barring the loss of atmosphere or some big impact – that energy can be lost – and that is by radiation. If you reduce the percentage of thermal radiation which is able to leave the system but hold the rate at which thermal radiation enters the system constant, things have to heat up. Conservation of energy.
For radiative equilibrium (as it can in fact be applied to the climate system as a whole) to be achieved after rendering the atmosphere more opaque to thermal radiation, the temperature of the climate must rise to the point at which more thermal radiation is being emitted, ultimately to the point at which the rate at which radiation is being emitted equals the rate at which thermal radiation enters the system. Conservation of energy.
Anyway, I am still quite an amateur in this area myself – philosophy major turned coder – so I would recommend beginning with some genuine resources. Like AIP. Or look at some of the earlier posts here. Real climatologists. Strong backgrounds in physics. I know of a particle physicist who grants them a well-deserved, deep and abiding respect.
Hope this helps…
[[Evolution hasn’t fully explained . . . why 99+% of evolutionary changes are not for the worse]]
Natural selection works by saving the changes for the “better” (i.e., more fit to the current environment) and eliminating the rest. By definition, the permanent changes will be those for the “better.”
tamino,
I understand that you want to stick to the surface temperature, the paper doesn’t
Their [Lockwood] analysis relies on data on surface air temperature which, they say, “does not respond to the solar cycle”. Yet over the past 20 years the solar cycle remains fully apparent in variations both of tropospheric air temperature and of ocean sub-surface water temperature (Fig. 1).
So arguing against it through use of the surface temps is somewhat disingenuous.
More on surface temps:
In temperature variations other than those in the surface record favored by Lockwood and FrÄohlich, the Sun’s in°uence remains obvious.
Then there is this:
When the response of the climate system to the solar
cycle is apparent in the troposphere and ocean, but not
in the global surface temperature, one can only wonder
about the quality of the surface temperature record. For
whatever reason, it is a poor guide to Sun-driven physical processes that are still plainly persistent in the climate system.
[Response: There is apparently some solar signal in sea surface temperatures, but I doubt that the analysis that Svensmark and Friis-Christensen showed really gives a correct picture. They are not offerening much detail about their analysis, so I have not been able to repeat it. -rasmus]
There are plenty of other reasons for wondering about the surface temp measurements, for instance the “divergence problem” is not confined to the surface temp relationships with tropospherice temps, and near surface ocean temps.
An anomalous reduction in forest growth indices and temperature sensitivity has been detected in tree-ring width and density records from many circumpolar northern latitude sites since around the middle 20th century. This phenomenon, also known as the “divergence problem”, is expressed as an offset between warmer instrumental temperatures and their underestimation in reconstruction models based on tree rings
http://climatesci.colorado.edu/2007/05/04/a-new-paper-on-the-differences-between-recent-proxy-temperature-and-in-situ-near-surface-air-temperatures/
But I really don’t want to go down that rathole. My problem with your response is that you retreat to the surface temp record to argue against the paper, when clearly they make the point several times that they are not talking about the surface temp except for one highly qualified observation, having nothing to do with their central argument.
I will read your link on the futility of high frequecny analysis, but I would think that the proof is in the pudding in terms of this paper. Correlations to the solar cylcle have been found in 19th century British grain prices and even ancient Egyption records kept on flooding of the Nile.
Re Rod #89
On your comment: “Evolution hasn’t fully explained the “explosion” periods, specie to specie evolution, or why 99+% of evolutionary changes are not for the worse, as probability would have it. (Hey! How ’bout an invisible hand of an intelligent designer? Just a thought.)”
This may appear off-topic, but it isn’t fully. There is a common theme that runs right through much of “denialism” of climate change science, and so-called “intelligent design” (in fact it’s the very fundamental basis of ID), namely the promotion of ignorance as if ignorance was a valid “debating” tool. In other words the pretence that we (science) don’t know what we actually know pretty well. Obviously having pretended that science hasn’t established well-supported explanations for a particular observation, one is free to assert the role of new hypotheses (ID, cosmic ray flux effects on climate) for which there isn’t any particular scientific evidence. Of course (coming back to Cosmic Ray Flux’s!) one doesn’t rule out CRF effects on climate (it remains to be seen), but in asserting a role for it, one should do so in the light of evidence, for which there is little of substance so far (after all in the web report of Svensmark and Friis-Christensen that’s the topic of this “thread”, their own analysis demonstrates that the CRF has made no contribution to the warming of the last 35 years).
Likewise with your three points. One could pretend that evolutionary theory can’t “explain” species explosion, species evolution, evolutionary change. But why do so, when we know that it can?
Specifically:
1. “Explosion” periods – these often occur after massive extinctions and are anyway associated with the opening up of new niches. A very detailed and entertaining account of the Cambrian explosion, for example, from an evolutionary perspective, can be found in S.J. Gould’s “Wonderful Life” (Penguin books 1991), which, if slightly out of date in the details, captures the general themes of this particular “explosion” rather well.
2. species to species evolution. We understand this pretty well indeed from an evolutionary perspective. New species can arise via reproductive isolation and genetic drift. For example, considering one of the most slowly evolving species (sharks), there was a separation of a single species into two discrete species in the Atlantic and Pacific respectively, upon closing of the isthmus of Panama many millions of years ago. There is a vast multitude of data on this subject.
More specifically, there are many examples in which the speciation process is known in extraordinary detail in lower organisms through comparative analysis of genomes. An excellent example out of dozens (see reference below) is the speciation of bakers yeast (Saccharomyces cerevisiae) which is known to have occurred via a genome duplication event in the ancestral species, followed by independent mutation of some of the duplicated proteins to yield in time a species having an entire novel metabolic process (the ability to metabolise the sugars that were appearing at that time in the plant world). We know which duplicated ancestral proteins mutated into which specific novel proteins (the duplication event allowed the original functions to be retained in one of each of the duplicated pairs, while the other was “free” to change and eventually acquire new functions), and can follow the mutation events since we know the genome sequences fully….
M. Kellis, B.W. Birren and E.S. Lander
“Proof and evolutionary analysis of ancient genome duplication in the yeast Saccharomyces cerevisiae Nature 428, 617-624 (2004)
3. It depends what you mean by “evolutionary changes”. Considering mutations, most evolutionary changes are not for the worst. Most mutations (e.g. single base mutations whether transpositions or transversions, but not additions or deletions, especially if these don’t occur in groups of three) are neutral, neither worse nor better, although they are part of the process whereby genetic diversity arises within populations that may ultimately leads to speciation. Secondly the vast bulk of phenotypic evolutionary changes (all the one’s that were “for the worse”) have been lost in the depths of time…it’s called “Natural Selection”.
[Response: Take the ID stuff somewhere else. It is OT on this site. – gavin]
This is a beauty
I doubt that any “scientist” who is proposing cosmic rays as the cause of the trend towards higher temperatures –Timothy Chase
Scientist in quotes, as in Svensmark and Christensen are not really scientists. We can’t hold the site responsible for all of the posts, and I don’t believe in limiting speech, but forgive me if I find this kind of rhetoric disturbing. This kind of rhetoric creates skeptics, IMHO.
Ray Ladbury,
It is not that brief, but here is a lecture on the subject from Sami K Solanki, Max-Planck-Institut für Aeronomie, Germany. Sorry if the answer is not simple enough.
http://www.blackwell-synergy.com/doi/pdf/10.1046/j.1468-4004.2002.43509.x
Before you fear to read it, I will note that at the end, he agrees with arguments made on this thread, although this was prior to the paper by Svensmkark and Christensen.
After 1980, however, the Earth’s temperature exhibits a remarkably steep rise, while the Sun’s irradiance displays at the most a weak secular trend. Hence the Sun cannot be the dominant source of this latest temperature increase, with manmade greenhouse gases being the likely dominant alternative.
I suspect that, like tamino, he is referring to surface temperature measurements.
Other highlights:
Assuming that the relationship between solar activity and irradiance found over the solar cycle also acts over longer times, it is then possible to work out that the Sun was between 2 and 4 Wm–2 less bright during the Maunder minimum than today.
Support for this conclusion is provided by the fact that the magnetic field of the Sun does not disappear at activity minimum when there are no sunspots on the solar surface, but rather that a background of magnetic flux, partly concentrated into the magnetic network, continues to be present.
There is evidence from multiple sources that this magnetic background changes with time. The strongest such evidence comes from the increase in the geomagnetic AA-index over the last 150 years, which has been used by Lockwood et al. (1999) to reconstruct the interplanetary field, closely related to the Sun’s open magnetic flux. Solanki
Interestingly, despite the robustness of the proxy and relation,
Support for the important role of the magnetic field at the solar surface is provided by the fact that the irradiance variability can be reproduced quantitatively by a simple three-component model, with the individual components representing the quiet Sun, faculae and sunspots. … This suggests that the basic premise underlying such a model is correct and that it is indeed the manifestations of the magnetic field at the solar surface (i.e. sunspots and faculae) that are responsible for the irradiance variations.
the IPCC seems to have removed it from their consideration in AR4.
The reduced radiative forcing estimate comes from a re-evaluation of the long-term change in
solar irradiance since 1610 (the Maunder Minimum) based upon: a new reconstruction using a model of solar magnetic flux variations that does not invoke geomagnetic, cosmogenic or stellar proxies; improved understanding of recent solar variations and their relationship to physical processes; and re-evaluation of the variations of Sunlike stars. AR4 TS 2.4
I guess I will have to go read the detailed report from AR4 to figure out what work has been done recently which overturns the work or solar and astrophysiscists and apparently invalidates Solankis comments. It should be interesting to read about this revolution in solar physics over a couple short years. I wonder why it never made the papers?
Re #98 Oh yes, Barrett. Among other idiocies, Barrett depended on a value of radiative lifetime for vibrationally excited CO2 which was more than 1E6 times too short, and which, had it been correct, would have meant there was no local thermodynamic equilibrium as he was using the lifetime for collisional de-excitation of CO2. You might want to look at the replies and comments in Spect. Acta B. Barrett had not a clue
You should read the AR4, partly to convince yourself by checking their references that the papers were indeed published even if you didn’t see them. It’s an old philosophical conundrum: “If a theory falls in the forest of published papers but I didn’t read about it, did it happen?”
For another take on it look at the debunking of the ‘Swindle’ movie’s graphics, where they added some lines and cut off others to show what appeared to be a very tight match between temperature and sun — and got caught at it. There’s a whole topic at RC about that movie earlier.
Re: #110 (yorick)
It was Svensmark & Friis-Christensen who made the ridiculous claim that “global surface temperatures have been roughly flat since 1998.” I contradicted this claim using solid statistical analysis. I also pointed out the disingenuous nature of accounting for phenomena like el Nino (although they don’t seem to say how) in order to make their case, then choosing a powerful el Nino as the starting point for their claim about the surface temperature.
So: they refer to the surface temperature. You quote them on it. I respond by addressing the issue raised by them and referred to by you. Then you accuse me of a “retreat to the surface temperature record.” Very revealing.
Yorick, First, I rather doubt that your 3 parameter model comes close. Second, correlation is not causation. A lot of things follow solar cycle, but it is a huge step from that to attributing the cause to GCR and a mind-blowingly huge step from that to attributing the significant temperature rise we have seen in the past 30 years to a putative tiny change in GCR flux, for which there is zero evidence. Why you choose to do this when we have a perfectly adequate explanation is beyond me.
I do not doubt that Svensmark et al. are scientists. I also do not doubt that individual scientists are subject to their own prejudices. The GCR camp is devoid of actual climate scientist, and moreover, I don’t see much evidence that they understand GCR fluxes either. For instance, consider the facts that:
1)There is no evidence of any systematic change in neutron fluxes since 1952.
2)There is no evidence in satellite data of any trend in GCR fluxes except for the solar cycle.
3)We still use the same GCR model to predict upset rates for electronics on satellites with no evidence of a change in the systematic error the model introduces.
Add to this the fact that the GCR hypothesis cannot reproduce either the quantitative or qualitative characteristics of the current warming epoch, while anthropogenic ghg do this quite well, and the only conclusion I can come to is that the GCR mechanism is a solution for which there is no problem.
Re Yorick #113 and your conclusion:
“I guess I will have to go read the detailed report from AR4 to figure out what work has been done recently which overturns the work or solar and astrophysiscists and apparently invalidates Solankis comments. It should be interesting to read about this revolution in solar physics over a couple short years. I wonder why it never made the papers?”
(This in relation to the reduction in the value of the increased “strength” of the radiative forcing since the Maunder Minimum- you quote from Solanki’s 2002 article:
“…that the Sun was between 2 and 4 Wm–2 less bright during the Maunder minimum than today.”)
In fact this reduction in the value of the solar increase did “make the papers”. For example here’s a paper by Sami K. Solanki from 2007 in which you can see that he himself has reduced his estimate of the increased solar output since the Maunder Minimum( down from 2 – 4 Wm-2 in 2002 to 1.3 W m-2 now):
Reconstruction of solar total irradiance since 1700 from the surface magnetic flux
Krivova NA, Balmaceda L, Solanki SK Astronomy & Astrophysics 467, 335-346, 2007
Results. Our model successfully reproduces three independent data sets: total solar irradiance measurements available since 1978, total photospheric magnetic flux since 1974 and the open magnetic flux since 1868 empirically reconstructed using the geomagnetic aa-index. The model predicts an increase in the solar total irradiance since the Maunder minimum of 1.3(-0.4)(+0.2) Wm(-2).
Notice by the way that no one is arguing that changes in solar properties haven’t affected the climate (or earth’s energy balance) since the Maunder Minimum. The point is that there is no evidence of any solar contribution to the very marked warming of the last 30-35 years. Note that Svensmark and Friis-Christensen themselves conclude that solar contributions to overall warming have been negligible, at best, since 1958.
Re Gavin #111
Many apologies for pursuing the evolutionary point. I knew it was rather off-topic. However I wanted to establish again in this case that one cannot use ignorance and misrepresentation of a scientific field as an argument that the field is somehow deficient.
I won’t do it again!
Timothy, a clarification (again?): I think you give grey bodies a bad name. There are many instances where things are exceedingly close (5%?) to greybody and even blackbody radiation over the preponderance (98%+?) of wavelength that they are a long ways from “only theoretical”, and for all practical and scientific purposes can be considered pure grey/black bodies. Earth, Sun, most heating elements, cosmic background come to mind. Is this not true? (Doubtful if this alters your thrust, though.)
I’m a global warming moderate, but this sort of counter-skepticism makes climatology resemble the polemics of a belligerent partisan than objective empiricist. Trashing the reputation of other scientists puts everyone’s reputation in a bad light and debases the science.
Were I just to take the agnostic view on this, solar cycles are just one parameter amongst many: A loss of low-lying clouds would just be one more compounding effect in the observed heating trend. The question needn’t be a yes-or-no matter, but a question of degree, and by what margin. Considering that some aerosols provide particulate support for cloud formation it could be that any solar cycle effect is more than offset by other aerosols. There is no one single driving force in such a complex system, even if the correlation looks compelling. The questions just raise more questions, suggesting more research is needed.
[Response: I don’t think it’s appropriate to call one-self as ‘moderate’ or ‘agnostic’. The crux of this issue is whether there is evidence for the interpretation offered by the GCR-guys. I see no empirical support for the notion that GCR are responsible for the recent warming. Do you? -rasmus]
As for low-lying clouds, there are other factors to consider, such as soot. I haven’t seen any discussion here regarding the new-found question of aerosol soot, just found by the INDOEX team to have a net *HEATING* effect. Prof. Ramanathan & his team have found:
1. Over the Indian Ocean (Maldives) 50% of the heating heretofore ascribed to CO2 is actually caused by airborne soot originating from the vast Asian Brown Cloud.
2. Over the vast Pacific (30% of the Earth’s surface), soot’s heating effect accounts for 40% of the heating (again, formerly ascribed to CO2). Most of the sootfall in the Western USA, for instance, is from Asia (China…).
3. Hansen (2003, Hansen & Nazarenko) found that soot deposition is responsible for *most* (90%) of the Arctic melt-off due to the snow-darkening heat-absorbent effect of soot (lowering ice & snow albedo in the Arctic & sub-Arctic tundra, taiga, etc.). Hansen states that although the Arctic melt-off represents 25 percent (yes, 25%) of all observed global warming, he was most concerned about the other 75 percent (attributed to CO2). Most of the sootfall in the Arctic is from Asia & Siberian oil fields, etc.
4. Other global sources of airborne soot include diesel emissions elsewhere in the world, slash & burn itinerant agriculture and cook fires. I can only speculate whether these sources might account for yet more global warming, but it’d be consistent with Ramanathan’s findings. Another 5 – 15 percent perhaps?
5. Ramanathan has also commented that the heating effect of soot seems to inhibit formation of lower altitude clouds, causing yet additional net heating (loss of high cloud-top albedo & surface shading, both). I see others claim there have been no net loss of low-lying cloud cover, but then there are net global averages vs. average regional anomalies, and which is most representative of climate change? Sometimes I have a hard time telling from some of the discussions which is which.
6. Ramanathan & others have noted that the mid-tropospheric heating of the brown clouds, coupled with the snow-darkening effect of soot, makes brown clouds a very likely culprit in glacial recessions in the Himalayas. The Himalayan glacier fields lie at exactly the same altitude as the brown cloud layers, so directly vulnerable to both the atmospheric heating & soot deposition. It could well be that many tropical and subtropical glaciers are suffering from manifold assaults from human activity. Coupled with deforestation decimating arboreal microclimates then perhaps these very same high-altitude mountaintop glaciers are also suffering from loss of recharge precipitation.
Were I to tally all the global heating effects of soot, I’m ballparking anywhere between 33 percent (Pacific airborne + Arctic ice loss) to 48 percent (WAG another 15% for other global soot sources). Accounting for only atmospheric effects could soot account for a third of all observed GW (75% atmospheric heating div. by 25% airborne soot)?
[Response: My initial though is: wouldn’t you see much stronger heating in the troposphere if the soot caused a warming? But, then again, I think it’s more appropriate to use climate models rather than my brain to compute the effects of the various factors which may be involved. -rasmus]
This is not to exculpate CO2, but perhaps abating industrial soot would be a good, relatively inexpensive place to start that’ll produce quick, tangible results (Arctic & tundral reclamation, normalized monsoon patterns in S. Asia…). Soot clears from the air quickly, as opposed to excess CO2 which will take nearly a century to self-remediate. CO2 is far-more insidious b/c of it’s long-term accumulation and effect, but the soot will have to be abated, regardless & as a first serious abatement project would serve well to obtain manifold benefits that’ll help societies commit to global progress on CO2 mitigation.
See my blog: http://www.scientificblogging.com/the_soot_files
Timothy, it’s simple: because we have a reasonable, even very plausible, explanation/speculation on how things work, does not mean there are not holes in the theory that may or might not go away or conversely grow to overshadow the theory. A person’s (or even many persons’) firm belief that his theory is correct and complete does not make it so either. So goes evolution… and climate science. Do we none-the-less have to go with the best we have? Yes, while continuing to try to figure it out more completely.
Gavin’s right — I shouldn’t discuss ID. In my defense, though, it comes up when the smearers call us skeptics deniers and claim we’re just like those dirty crazy ID folks… But, ‘nough of that.
ps, sorry. I meant Chris, not Timothy above.
Harmon (98, 107) — If the AIP explanation isn’t enough for you then you need to obtain and study one or more books on atmospheric physics. The basics of so-called greenhouse gases has been understood for over a century now.
Extraordinary claims require extraordinary evidence. But first, learn the known physics.
WRT to my post (#120) … I want to clarify that Ramanathan’s model suggests 40% warming over the Pacific (30% Earth’s surface). That may then account for roughly 12% of AGW. Tallying the Artic soot-driven effect (~ 22%, since 90% of the Arctic melt-off appears to be soot-driven), and the Pacific aerosol soot-driven warming alone & that tallies to ~ 33%.
That tally doesn’t include the net soot-driven warming over Asia & the Indian Ocean, or other global seasonal soot-driven anomalies. AFAIK, the research isn’t there, so any number I ballpark is purely a WAG proffered only for thought & discussion.
IAC, Ramanathan himself states that soot abatement could well offer a way out of the current conundrum, so don’t take it just from me, look to a real expert and leader in the field.
/lee
Timothy Chase, Thank you for your detailed response to Harmon’s points (#108). Although some of it was over my amateur head you said one thing that I have unfortunately failed to grasp in my (embarrassingly extensive) reading here.
You said: “… Greenhouse gases tend to emit more radiation than they absorb, not less…”
This was a light bulb moment for me. Many of the pieces of the puzzle fell into place when I read this. I’m sure I must have read this here before but somehow it did not sink in.
Thank you again. :-)
Leebert, When I was doing science journalism, one of the cardinal rules was: Never go with a single source. Aerosols including soot are among the forcers with the greatest uncertainties attached to them. My objection is that you assume that if they contribute more warming than thought, what would have to give is the contribution of greenhouse gasses–among the best understood and least uncertain of the forcers. That is not how things typically work. Likewise, the case with forcing by GCR–in order for there to be room for such a mechanism, they have to not only come up with a mechanism, they also have to show why some other mechanism contributes less. Even if they had such a mechanism, greenhouse effects would be the least likely place to find give, since they are constrained by multiple, independent lines of evidence.
This is one of the aspects that raises the ire of responsible climate scientists when outsiders come in and make a hash of science they do not understand. The other aspect that puts them on edge is the disingenuous use of data like that cited by Tamino. Interogators know that torture is an unreliable questioning technique, but it is especially unlikely to yield the truth when applied to data.
Harmon (#107) wrote:
Granted – but nitrogen and oxygen molecules collide with what greenhouse gas molecules that are part of the same atmosphere. And given how often the collisions take place throughout most of the atmosphere, these gases will be at the same temperature. Given the long tail of the Maxwellian distribution, some will have the energy needed to emit at the relevant frequencies.
Harmon (#107) wrote:
“Lifetimes”?
I believe what you are refering to are called “half-lifes.” That has a time component to it as well – and the implication that the subatomic particle, atom or molecule with the half-life has no knowledge of how long it has been in a given state. As long as a certain percentage are in a given state at any given time, a certain percentage will emit over a given unit of time.
Harmon (#107) wrote:
Conditions for a local thermodynamic equilibrium are typically satisfied are at 20 millibars or above. That is where a given greenhouse gas molecule will experience roughly a million or more collisions per half-life of the relevant states of excitation. Standard atmospheric pressure is approximately 1013 millibars. Somehow I think we can count on a local thermodynamic equilibrium in the troposphere.
As such, stimulated emission does not become an issue. We aren’t talking about population inversions, lasers or the like. For that sort of thing to take place the collisions would have to be much less frequent so that molecules would have a chance to absorb and emit radiation without collision and the radiation itself would have the ability to overwhelm the order imposed by the Maxwellian distribution due to molecular collisions.
Harmon (#107) wrote:
They do quite fine at emitting radiation. For example, at a temperature of 240 K, approximately 1.8 percent of CO2 molecules have sufficient energy for their 15 μm vibrational line to be excited. And given that no individual molecule is aware of how long it has been in an excited state, collisions in no way affect the ability of the population to spontaneously emit radiation.
*
Harmon (#107) wrote:
The radiative equilibrium which I am most concerned with is where the radiation entering our climate system is equal to the radiation leaving it. If the rate at which thermal energy leaves the climate system is lower than the rate at which thermal energy enters the climate system, things will tend to heat up. You argue that the thermal radiation which greenhouse gases absorb simply gets converts to molecular kinetic energy – with effectively none of it being reradiated at some later point. As such, you believe that greenhouse gases heat the atmosphere without cooling it by reradiating thermal radiation towards space or towards the ground.
If this were the case, how would the climate system achieve balance between the thermal energy entering the system and the thermal energy which leaves the system? Can’t be convection or conduction. The atmsophere can’t convect or conduct above where it ends. If the atmosphere becomes more opaque to radiation, the climate system must warm up until it is able to emit thermal radation at a rate that is sufficient to balance the rate at which thermal radiation is entering the system. This holds in the real world where greenhouse gases emit thermal radiation, and I presume it would hold even in your world where greenhouse gases only absorb thermal radiation, but never emit it.
*
Harmon (#107) wrote:
In #98 you made it clear that you confused a simple conceptual model of the greenhouse effect meant for students with our actual understanding of the phenomena itself. The conceptual model has numerous deficiencies – if taken as a model of the actual processes involved. For example, there is only one infinitely thin layer to the atmosphere. The atmosphere is treated as a grey body absorbing infrared at all wavelengths. There is no convection. There is only one gas.
In the actual models, climatologists have access to the empirically measured emissivities of over a million spectral lines, all neatly kept in in the HiTran database. They peform calculations for each gas at a resolution of roughly a degree by a degree at forty different levels of the atmosphere, with calculations of air speed, humidity, temperature and pressure being performed for each box in the the 3-D grid at a temporal resolution on the order of minutes, and even with the NEC Earth simulator from a few years back were performing over 32 trillion floating point calculations per second. They are employing atmosphere-ocean coupled calculations and incorporating both atmospheric chemistry and the carbon cycle.
If you plan on using a single Excel spreadsheet, you won’t have a tenth of the rows needed for just the spectral lines in the HiTran database. Somehow I doubt that your margin notes will stand much of a chance of undermining the basics of our understanding of the greenhouse effect, a large part of the core of twentieth century physics, including quantum mechanics, statistical mechanics and radiation transfer theory, or the wealth of evidence to the effect that we understand the basics of how our climate is changing.
However, if you are intent upon overturning everything modern science has learned, you might take the suggestions which have been offered to you to the effect that it would help if you learned the basic physics first – and perhaps familiarized yourself with what a climate model is – before making your revolutionary contributions to twenty-first century science.
The problem I have with rejecting non-TSI-mediated solar effects on climate is the effect this has on the fit to the temperature profile over the 20th century. This profile shows a rise in the early decades of the 20th century, a flat-to-downward trend mid-century and then a second rise over the last quarter of the century that persists to this day.
If we subtract greenhouse-induced warming from the recent warming and from the early 20th century warming we find that the residual warming is greater then than now.
Aerosols can not explain the difference. Natural aerosols are on average smaller than human-produced ones and do not show any temporal trend that is explains the observations. For the greenhouse-corrected temperature rise to be greater 80 years ago than now would require that aerosols (which exert a net cooling effect) were smaller 80 years ago than now. This is not true.
I have read that climate scientists have acknowledged a solar contribution to early 20th century warming. Solar activity reconstructions by Lockwood as well as the sunspot record show evidence of an increase in solar activity in the first half of the 20th century. As far as I can tell (see the url linked) the magnitude of the early 20th century rise in multidecade average solar activity is not more than the magnitude of a single solar cycle. We know that the change in TSI over this cycle is only about 1 watt/m^2 which translates to about 0.18 in solar insolation. This is too small of a forcing to explain much of the warming then.
So it would seem that a second mechanism by which solar activity affects climate would explain the early 20th century warming. Such an effect would be irrelevant to the recent warming since solar activity has been essentially flat for the last half century (and over the entire recent period of rising temperature)
Re Rod #121
You suggest:
Chris, it’s simple: because we have a reasonable, even very plausible, explanation/speculation on how things work, does not mean there are not holes in the theory that may or might not go away or conversely grow to overshadow the theory.
I agree that it is simple Rod. There may very well be holes in a theory that may or may not go away. But we have to be specific. Which holes? We don’t assume that a theory has holes just because it’s a theory. Skepticism must have some specific basis, otherwise it’s something else. And one has to be careful to determine whether the “holes” are in the theory and not in the knowledge or understanding of the skeptic.
Incidentally I’m not picking on a specific class of “skeptic”. I’m assuming that we’re all skeptics.
tamino,
You cherry pick one comment about the surface temp, where you decide what they meant by “roughly”, and completely ignore the bulk and central point of the paper, then declare the paper “disingenuous”. Cherry picking.
Chris, thanks for the update on Solanki.
As for CRF and cloud formation, I guess that we can wait until the CERN experiment to see if there is a mechanism there or not. There is a bit of hand waving going on now, but there is more than a little bit of hand-waving going on in the surface records. Explain to me exactly how proxy temperature teleconnections work, for example.
This issue is not settled, pretending that it is one way or another is foolish.
In re: #126 (ray ladbury): I’m not impressed by an appeal to authority. I cited V. Ramanathan of the Scripps Institute, his reputation in the field is well known. I clearly disclosed my own speculations on the matter. So you can strawman me all you want, I’m discussing the topic, not my authority or anyone else’s in these fora.
My point is quite clear: A noted authority in the field has cited that his team has discovered a heretofore unexpected, unexamined and unanticipated net heating effect of airborne soot that was formerly ascribed to CO2. This effect spans the Indian Ocean, S. & S.E. Asia, the vast Pacific. Another authority of great renown in the authority presented a research paper that identified soot as causing 9/10ths of the observed warming in the Arctic.
Those TWO authorities are V. Ramanathan of the Scripps Oceanographic Inst. AND Dr. James Hansen of GISS / NASA.
I would hope the participants in discussions would at least making a passing attempt of going to my blog and do the reading themselves before they start cast aspersions suggesting that I’m pulling a single-source rabbit out of my hat.
re: #120 – my post w/ embedded comments from rasmus:
Rasums, I’m simply pointing out that some of the posters on this discussions are resorting to polemics. I can’t think of a better way to make one’s own position look worse than to make nakedly acerbic remarks about someone else.
Also, you wrote:
[Response: My initial though is: wouldn’t you see much stronger heating in the troposphere if the soot caused a warming? ]
Had you read the articles on my blog, you would find that soot does in fact cause much stronger heating in the troposphere, more than it causes surface cooling. The net difference is +1 degree C/w2.
Rasmus wrote:
[ But, then again, I think it’s more appropriate to use climate models rather than my brain to compute the effects of the various factors which may be involved. -rasmus]
I’m just passing the information along, you can look into the matter yourselves before the “skeptic blogs” pick it up & make you look unprepared.
I’m not in the least impressed by the “shoot the messenger” attitude in this forum. Why have an open forum if this is the way you treat guests?
Re: #130 (yorick)
Alas, poor yorick. I’m not the one who chose the 1998 starting point, that was Svensmark & Friis-Christensen. I’m not the one who referred to the surface temperature record, that too would be S&F-C. And I’m not the one who quoted this ridiculous claim in the first place. That would be you.
But you still want to accuse me of “cherry-picking” and a “retreat” to the surface temperature. You also accuse me of deciding “what they meant by roughly.” The linear-regression trend in GISSTEMP data (that referred to by S&F-C) from 1998 to the present is 1.9 deg.C/century. So despite starting with an el Nino, the trend estimate turns out to be larger than the estimate for the last three decades. That is absolutely not flat. Not even “roughly” — by any definition of the word.
Either S&F-C know this, in which case they are deliberately misleading the reader, or they don’t, in which case they show considerable naivete making such a claim. And they surely know that 1998 was a big el Nino, and that choosing it as a starting point to claim the absence of a trend is ludicrous. Too bad for them that it backfired. Too bad for you that you can’t just admit that they’re wrong; we’d take you more seriously if you did.
Timothy,
That was a very pleasant post. Thank you. I will read the others in a minute. Busy day.
With respect to the opacity of CO2, this is a function of pathlength.
When considering absorption and emission, everything has to be normalized. BB radiation is generally related to surface area. Radiation is an extensive phenomenon. This means quite simply, more surface area, more radiation.
For gases, you have path length. If you consider:
absorbance = absorptivity coefficient * path length * concentration
Concentration will have a cubed length term (or liters, but that can be converted to a cubed length term) in the denominator. Path length is a length term. The product of path length and concentration can be interpreted as “per cm^2” or something analogous.
The CO2 is not emitting more energy that it absorbs. At about 700 cm-1 and 300 K, I will maintain that CO2 emits negligible radiation. You will need an experiment to overturn the theory of gas phase infrared spectroscopy to change my mind on that one. Then I’ll buy it.
Anyway, back to the point about radiation being an extensive characteristic. THis means that regardless of the absorption of CO2, be it very large or very small, if you take a path length long enough, you will see absorption of all of the IR energy in its bands. This cannot be construed as having the same radiation intensity characteristics as the solid. It is similar to comparing the radiation from two solids, one with a huge surface area and one with a small surface area.
By the way, if you would like to convince me that an important increase in temperature will result from an increase in current CO2 levels, there is something you might try. I really haven’t a clue what the result would be.
Consider that the atmosphere is quite heterogeneous with respect to phases present, solids, liquids, gases, all available. Now gases at tropospheric temperatures basically don’t emit (it’s really small). However, condensed phases spontaneously emit radiation quite well. In fact, the condensed phases in the atmosphere are continually emitting radiation in all directions. Yes, this is spontaneous emission. Gases at the same temperature aren’t doing it noticeably, but condensed phases are.
In any event, since CO2 absorbs radiation, and can be considered not to emit it, but rather to pass it along collisionally, think about the time it takes for energy to travel from condensed phase speck to condensed phase speck.
Without CO2, the energy is moved along by radiation, traveling at the speed of light. With CO2 absorbing and not emitting, the transfer of energy in the atmosphere is slowed to approximately the speed of sound.
Working this problem will require knowledge of particulate concentrations and surface area (surface area is the key for large emission – remember extensivity, small particles have large surface area taken togther).
It is quite possible that the average distance between particles is not saturated, therefore more atmospheric CO2 will increase that absorption, decreasing the rate of energy transfer.
Because the energy in the 15 micron band has been slowed to the speed of sound due to absorption by CO2, the particles at higher altitude receive energy more slowly, and do not get as warm. Therefore the particles emit at less radiation.
The net effect (if this is realistic) serves your ends well. Less energy is emitted, so warming further down is to be expected. Also, if you consider that the presence of CO2 lowers the temperature of high altitude particles, you can actually consider CO2 as drawing energy from the entire bb spectrum, a result you simply can’t get if you depend on absorption and emission of the gas alone.
THis sort of a model would also satisfy me, as solids would absorb and emit like solids, and gases would absorb (and pretty much not emit) like gases.
Anyway, food for thought. I don’t know the answer, but would find such an argument, if it can be proven, to be pretty convincing. The current argument that requires a large amount of direct spontaneous emission from a gas at 400 torr and 255 K is simply not at all convincing.
Cheers.
I will look for your reply. Believe it or not, I actually enjoyed your posts.
Its good to see that this site is posting more from both sides of the fence. It enhances credibility and in the end both groups appear to have a commonality in the science of climate. The debate is good and the more skeptical sites should do likewise
cheers
L & F did confrim the possibility of a big fall in solar activity, with an uncertain impact on climate. They also said that ‘solar radiative forcing variations were amplified by some mechanism that is, as yet, unknown.’
Re #120 leebert
You have stated:
“Hansen (2003, Hansen & Nazarenko) [did you mean 2004? – I can’t find a Hansen and Nazarenko 2003] found that soot deposition is responsible for *most* (90%) of the Arctic melt-off due to the snow-darkening heat-absorbent effect of soot (lowering ice & snow albedo in the Arctic & sub-Arctic tundra, taiga, etc.). Hansen states that although the Arctic melt-off represents 25 percent (yes, 25%) of all observed global warming, he was most concerned about the other 75 percent (attributed to CO2). Most of the sootfall in the Arctic is from Asia & Siberian oil fields, etc.
But you really need to point out that Hansen et al. state that this 25% represents all global warming since 1880
i.e. they say:
[J. Hansen and L. Nazarenko (2004) Soot climate forcing via snow and ice albedos Proc. Natl. Acad. Sci 101 423-428.]
Our estimate for the mean soot effect on spectrally integrated albedos in the Arctic (1.5%) and Northern Hemisphere land areas (3%) yields a Northern Hemisphere forcing of 0.3 W/m2 or an effective hemispheric forcing of 0.6 W/m2. The calculated global warming in an 1880–2000 simulation is about one quarter of observed global warming.
When was most of this black carbon induced warming manifest? This is addressed in a study published last month in Science:
[J. R. McConnell et al (2007) 20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing. Science 317 1381 – 1384]
Analysis of Greenland ice core deposits indicates that the dominant 20th century black carbon forcing via albedo efects was in the early to mid part of the 20th century. If you examine their Figure 2 for example, you can see that the black carbon is negligible apart from some spikes (volcanos??) up ’til the start of the 20th century and shot up to peak at around 1915-1920 where it flattened out through the 30’s and 40’s dropping down to a low value again by around 1950. Apart from some spikes, the black carbon levels in the Greenland core have been rather low since then right through to 2002.
as McConnell et al say: “The median in estimated surface forcing in early summer throughout the Arctic was 0.42 W m–2 before 1850, 1.13 W m–2 during the period from 1850 to 1951, and 0.59 W m–2 after 1951.”
Note that Hansen and Nazarenko suggest that this total warming contribution (since 1880) may have been around 0.2 oC most of which has already been achieved.
i.e. “Our estimate for the equilibrium global warming of current soot levels is 0.2°C, most of which is already achieved. If snow albedos were restored to their pristine values, a future cooling tendency of that magnitude would be introduced, partially countering opposing warming forces and thus helping to keep us from reaching the level of DAI. [“DAI” = Dangerous Anthropogenic Interference] “
So at least from the paper that you have brought to our attention and the very recent data of McConnell et al., the effects of black carbon were largely manifest in early to mid 20th century warming. Can use this data at all to suggest that black carbon effects have made much of a contribution to warming since around 1970?? On the other hand there are some exmples desribed by Hansen and Nazarenko where mountain glacier melt has occurred in areas where warming hasn’t been particular strong, and that might be attributed to local albedo effects of black carbon on ice….
Dan W (#125) wrote:
Not a problem. I am still pretty new to this, and more detailed responses give me a chance to think through things some more myself.
The net cooling of the atmosphere by greenhouse gases was a bit of a lightbulb for me a few weeks back, too – something which I had to understand in the context of moist air convection (otherwise how can explain the fact that the troposphere warms?), but which also helped to explain why the stratosphere cools.
The greenhouse effect actually does result in the net warming of the troposphere, but only indirectly. The backradiation from the greenhouse gas longwave emissions warm the surface, increasing moist air convection which thereby warms the atmosphere. But the direct effect is that of net cooling by emission rather than warming by absorption.
The fact that the stratosphere cools as the result of an increased greenhouse effect – something which at first seemed paradoxical to me – follows quite naturally once one understands this. The troposphere will warm, but the stratosphere cools. But both cool as the direct effect of an increased greenhouse effect. However, only the troposphere warms as the result of moist air convection. The tropopause which marks the end of the troposphere and the beginning of the stratosphere is essentially the boundary where moist air convection comes to an end.
*
Nevertheless there are regions of the spectra and atmosphere where a given greenhouse gas will actually have the net effect of warming the atmosphere. One might regard it as quite negligible by comparison with the cooling that occurs throughout most of the spectra and atmosphere, but it is there nevertheless.
There is a neat diagram that was produced by a company called “Atmospheric and Environmental Research” which shows this. Computer generated and not directly off of atmospheric measurements, but something which complements them nevertheless.
Actually, I guess you could say that it is the product of a vast number of laboratory experiments.
What they have done is calculate the net cooling or in some cases net warming at each wavelength and identified which gas is responsible at a given pressure, or equivilently, altitude. This is based upon the pressure and temperature of the atmosphere at the given altitudes and the emissivities as measured in the labs. Undoubtedly they are going off of the HiTran database which currently has the results of empirical measurements of the emissivities at over a million different lines total.
Radiation & Climate: Major Projects
Line-by-line calculation of atmospheric fluxes and cooling rates 2
http://www.aer.com/scienceResearch/rc/m-proj/abstracts/rc.clrt2.html
This appeared in:
Clough, S.A. & M.J. Iacono, Line-by-line calculations of atmospheric fluxes and cooling rates 2: Application to carbon dioxide, ozone, methane, nitrous oxide and the halocarbons, J. Geophys. Res, 100, 16, 519-16, 535, 1995.
Looking at it you will notice that there is a fairly large “grey oval” near the center associated with ozone. This is where the effects of ozone lead to a net warming of the atmosphere. Fairly minor – in the neighborhood of a thousandth of a degree per wavenumber*day, but there nevertheless. This is due to the absorption of ultraviolet from sunlight even before it reaches the surface. Then there is the small “light grey circle” to the left associated with carbon dioxide. Roughly 200 mb I believe between the wavenumbers of 600-700 cm-1. Not really sure why that is there.
But the rest of the diagram shows a great deal more cooling of the atmosphere as the direct effect of greenhouse gas longwave emissions. The emissions outweigh the absorptions throughout nearly all parts of the diagram.
In any case,
*
As I have said, that diagram is essentially the condensation of a great deal of laboratory measurements. But if you are looking for actual measurements of infrared emission in the atmosphere, there is a great deal out there. I included links to a fair amount of it in comment #555 to post Part II: What Angstrom didn’t know which I refered Harmon to in #90 but which he appears to have missed. As Ray Ladbury pointed out just earlier today (comment #330 to post Climate Insensitivity), when we take satellite measurements of the longwave emissions of greenhouse gases, what we are seeing is that part of atmosphere which is in the transition from being opaque to the longwave radiation to being transparent to it. Below that level, the radiation is absorbed and emitted numerous times. But when it reaches that level, the radiation is capable of being emitted without being absorbed again.
Now I understood as much, actually. However, thinking about it some more just a few moments ago, I realized that virtually all of the thermal radiation in those parts of the spectra which the lower atmosphere is opaque to will be absorbed if it is coming from directly from the surface. As such, if the atmosphere didn’t emit radiation, there would quite literally be nothing to image at the various altitudes in the respective wavebands. Nothing to show for 15 μm at 8 km altitude. If at a given altitude or below, the atmosphere is entirely opaque to radiation within a given band, then this implies that whatever radiation we might see in that band from a satellite has to be radiation which is finally being emitted by that atmosphere where it will no longer be absorbed along its path to space.
In a certain sense, this was also something I knew, but I suppose I just hadn’t thought of in quite the right way. But what it also means is that the images are quite literally images of where the longwave radiation is last radiated (or “emitted”) and finally escapes from the atmosphere, where by “escapes” one means that the photons composing that radiation are no longer absorbed along their path to space. The luminosity in those parts of the spectra is reduced from what it would be in the absence of the greenhouse gases, but for all intents and purposes, all of the luminosity is directly due to reemission by greenhouse gases – since all of the radiation coming directly from the surface is absorbed long before it gets to space.
Harmon posts:
[[In any event, since CO2 absorbs radiation, and can be considered not to emit it, but rather to pass it along collisionally, think about the time it takes for energy to travel from condensed phase speck to condensed phase speck.]]
And it also picks up energy collisionally, and the temperature increase applies just as much to the greenhouse gases as to the rest of the atmosphere, and being heated the greenhouse gases radiate more.
tamino, [edit] The validity of the paper does not rest on my defense of it, or your bulldog like tenacity in “refuting” one particular line about the surface temps. Your [edit] regression analysis, extrapolated over a century is all but meaningless, which you well know. But here, the paper would have been better without that aside. There, I said it. You know why the paper would have been better? Because removing the aside does not change its meaning one iota.
I take it that you have nothing to say about the signal in the troposhperic and near surface ocean temps, on which the paper centered?
Isn’t the warming supposed to originate in the troposhpere and isn’t the troposphere warming supposed to lead any surface warming according to AGW theory? I though this was due to the properties of CO2 and H2O where at low pressures, H2O stops canceling the bulk of the “greenhouse” effect at high altitudes due to “pressure broadening”. One of my biggest objections to the alarmism is the lack of a trend in the troposphere while surface temps are claimed to be on a 1.9C per century tear, per tamino, anway.
Belay that last question, I can see that there is an interesting discussion of the troposhpere temps going on right now in this very thread, which at first I took to be off topic.
Barton,
Net absorption for a gas.
Net Absorption = Stimulated Absorption – Stimulated Emission – Spontaneous emission.
The coefficients of stimulated emission and absorption are identical. Without spontaneous emission, the population of two states of different energy are driven to equal values by a radiation field.
Stimulated absorption and emission represent a combined effect on measured absorption, since the stimulated photons are coherent with the incident photons.
No, we’re not talking about lasers, that requires a population inversion. Light can jump a molecule up to an excited vibrational state, or down to the gound state if it begins in an excited state. It does this equally well in both directions.
The spontaneous emission component is present because an excited state can also decay to the ground state all on its own. This is the isotropic emission. It is the only emission component that will be useful for a model of a gas radiating in all directions.
The coefficient of spontaneous emission is related to the coefficient of stimulated emission by a factor that contains the third power of frequency. After excitation by high frequency light, the spontaneous emission from a gas becomes important. At energy differences of lower frequency, specifically in the vibrational and rotational levels, spontaneous emission from a gas is negligible, and is generally ignored.
For a solid, the spontaneous emission is large.
I suppose we could go on like this all day. I’ll get back to it if I can find time. If I get to posting again, I’ll try to throw in an explanation of the partitioning of kinetic and potential energies within a substance, and how this can account for the wide disparity in spontaneous emission between solid and gaseous phases.
By the way, Timothy, supercomputers are all well and good. However, checking the relatively simple models upon which computer codes are based can often be done with a pencil, in the margins of a textbook. Fancy computers and millions of lines of code aren’t capable of fixing a misunderstood physics model.
Cheers.
Harmon (#134): “The CO2 is not emitting more energy that it absorbs.”
You are right; CO2 is not emitting more energy than it absorbs. This would defy the laws of physics. Timothy did not say anything that defies the laws of physics
If I understand Timothy correcctly he said that GHGs (in general) emit more long wave (infrared) radiation than they absorb. The difference (in energy) is made up from the kinetic energy the GHGs absorb from the other atmospheric gasses. Therefore the (IR emitting) effect of GHGs (by themselves) is to cool the atmosphere.
However several other factors come in to play. Much of the IR energy (from GHGs) is reemitted back towards the earth where it warms the surface (or possibly other GHGs that absorb the same wavelength where the process is repeated).
Much of that surface warming is transferred back to the atmosphere though both conduction (lowest levels) and convection (upper levels). The high levels of energy required in to vaporize H2O (at low elevations) and released when condensing H2O (at relatively higher) is very significant to consider here.
See also post #139
I hope this helps. Let me know if I don’t get it yet.
Robinson, A.B., N.E. Robinson, and W. Soon (2007) Environmental effects of increased atmospheric carbon dioxide. Journal of American Physicians and Surgeons 12: 79-90
This morning I found a letter from Frederick Seitz in my mailbox asking me to sign a petition claiming to be skeptical on global warming. Enclosed was a print of this article. I have no idea why they targeted me. I’m an engineering professor, not a climatologist. In any case, I tossed the petition in the recycle.
yorick (#141) wrote:
Yorick,
If you have paid any attention to the issue of satellites and their measurements of both the stratosphere and the troposphere, you well know that first, we haven’t had any satellites prior to 1958, and second, with the early measurements, we didn’t take into account the fact that their sensors wore out with use. Once we did this and tracked the performance of the old with the new, it was pretty much problem solved.
Since then we have been seeing the nearly the same trends in satellite measurements of the troposphere that we have been seeing at ground. The biggest difference has been greater variability, where during the hot years there is generally a larger spike in the temperatures measured by satellites.
As for your statement that the trends measured over a century are meaningless, I haven’t a clue what you are talking about. The shorter the period, the less meaningful the trend. Two reasons. The first is simply a matter of pure statistics. Fewer points from which to judge the trend. The second is natural variability. El Ninos and the like.
Finally, why should the trend towards higher temperatures originate in the troposphere? Do you even understand the theory you are trying to argue against? Heating takes place at the surface itself first. The troposphere warms principally due to moist air convection. The net direct effect of absorption and emission by greenhouse gases (in all but some fairly minor areas) is to cool the atmosphere, not warm it.
Not that this should make much of a difference in terms of the trends themselves. Pretty much none whatsoever. But it strongly suggests that you lack an understanding of the causation involved.
Blank (#144). Good question.
See also: http://rabett.blogspot.com/
(Entries of 10/5/07 and 10/4/07)
re: #144, #146
Yes; at a local climate-change meeting, yesterday I met a retired USGS geoscientist who was astonished to get this in the mail. Fortunately, he knew enough to recognize BS. I’d suggest anyone else who gets one, go over to Rabett and say something, maybe we’ll get some idea of their targeting this time.
> some idea of their targeting
Perhaps asking the person who signed the cover letter what he thinks is going on?
Harmon (#142) wrote:
From what I understand, stimulated emission is fairly irrelevant in the atmosphere. We have seen it once that I know of in a stellar atmosphere, but that would make it a rare bird indeed – and demonstrates that we could pick it up if it happened in our own atmosphere on any large scale.
I believe the problem stems from the lack of enough photons. Rarely will the CO2 molecule absorb one photon only to be struck by another. You have to have a lot of photons going through the same bit of matter to do that. A fair percentage of the atoms would have to be in the excited state for this to occur. I believe this is what one might refer to as a population inversion – assuming a large enough percentage of the atoms are stimulated in this fashion. Prior to that the light coming from a laser – as one powers it up – is incoherent. I believe that is the spontaneous decay.
Setting this aside, it always results in two photons traveling in opposite directions. I am afraid it wouldn’t be much help in getting rid of the backradiation.
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It pays to learn the physics before you attempt to critique it. Defending it without fully understanding it is a little easier.
Chances are that its right in the first place: division of cognitive labor, many different lines of investigation, and great deal more brain power, the man-hours in a single day are quite significant, and down the centuries? Staggering. The connections you make will be connections that were already made before and form part of a coherent whole. But then again, the individual mind will oftentimes have to make the same connections several times before it becomes thoroughly integrated into various contexts. I will point one out to you in short order.
Which ever way the intelligence is divided up between us – and I honestly do not know – I’m afraid I still have you at a disadvantage.
To make a really big contribution you pretty much have to work at the edges. The stuff thats been around for a while and is more basic has been thought through and through, tested again and again.
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Harmon (#142) wrote:
Given the fact that there is two kilograms of anthropogenic carbon dioxide in the square meter column above your head, I doubt that there is any signficant difference – at least within this context – between the emission of the gaseous phase and the solid. The light passing through my cup of coffee falls off exponentially with the distance it travels. Same thing here – if you think about it. Cross-sectionally the gas might as well be solid given the column height.
And incidentally, Doug W is right: the extra energy for emission comes from the latent heat of moist air convection. Then there is the fact that the density of the atmosphere falls off exponentially with altitude – so photons that are upwelling have an advantage in making it to space without further collisions.
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Harmon (#142) wrote:
You have already demonstrated that you are confused with regard to the difference between a simple model meant to teach a single principle and the advanced models used by the climatologists. I pointed this out in 127. Likewise, the principle involving man-hours which I mentioned above most certainly applies – particularly with twentieth century science, a century which has seen more individual minds than all of the previous centuries of human civilization combined.
Furthermore, there are all of the tests which the basic approach of the models have been put to. Measurements of infrared radiation at various altitudes by satellites and planes. Measurements of upwelling radiation at the surface. The implications in terms of the stratosphere cooling while the troposphere warms. The data, the images…
Then there is that insight I had in 138. If the greenhouse gas absorbs all of the longwave in a given range of the spectra due to the atmosphere becoming entirely opaque over a given distance (remember that cup of coffee I brought up a few paragraphs before?), then without emission of radiation where the atmosphere turns from the opaque to the transparent, nothing will show up in a satellite image.
But the satellite images exist. Therefore the radiation is being emitted – somewhere. And given all of the lines of the spectra of greenhouse gases, it has the fingerprint of the gas which emits it. I realized the thing about the radiation coming from the layers where it is finally emitted for the last time – some time ago.
But I didn’t quite realize how this fit in to the argument with those who deny it emits. A little more integration on my part, apparently.
Now it is true that you might come up with something else a little while later. But the “greenhouse gases absorb but don’t emit”-gambit ought to be retired. Along with the contradictory approach of “its all stimulated emission so there is no backradiation”-approach you have been attempting more recently. Neither have any life left in them here.
Leebert, I find it interesting that as you protest that you are not appealing to authority, you find it necessary to give me his credentials. But even more interesting: In you haste to defend your wounded pride, you completely ignored the point of my post: that if soot and other aerosols do assume a greater importance, it is very unlikely that they will do so at the expense of greenhouse gasses, the contributions of which are constrained by a variety of lines of evidence. Finding evidence that CO2 contributes less forcing than expected would be much more difficult than finding evidence that soot contributed more.