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  1. “It wont happen” Hello?
    Ok- can someone please tell the eskimos and polar bears to stop hallucinating?
    everything is really ok
    That’s snow —not strawberry fields —“nothing to get hung about”

    Comment by tapasananda — 4 Oct 2007 @ 8:31 AM

  2. And now if Archibald could just change the laws of physics, we could make the problem go away! Sounds like an exercise in “faith-based” science. I wonder if he’d have much luck convincing some of the farmers in Oz who are losing everything they had due to drought?

    Comment by Ray Ladbury — 4 Oct 2007 @ 9:32 AM

  3. Did anyone publish Archibald’s paper in a journal somewhere? The link goes to “” — don’t science journals usually refuse to consider publishing papers that go out as PR first, preferring that peer review and journal publication precede public distribution?

    This doesn’t even have something like “to be published in, well, submitted to, er, rejected by Energy and Environment” credentials. Yet.

    Comment by Hank Roberts — 4 Oct 2007 @ 10:28 AM

  4. A quick search on Google Scholar yeilds only one other paper by David Archibald which appeared in that bastion of critical peer review “Energy & Environment”:

    “Solar Cycles 24 and 25 and Predicted Climate Response” appearing in Energy and Environment, Volume 17 No. 1 2006, pages 29–35

    “Projections of weak solar maxima for solar cycles 24 and 25 are correlated with the terrestrial climate response to solar cycles over the last three hundred years, derived from a review of the literature. Based on solar maxima of approximately 50 for solar cycles 24 and 25, a global temperature decline of 1.5°C is predicted to 2020, equating to the experience of the Dalton Minimum. To provide a baseline for projecting temperature to the projected maximum of solar cycle 25, data from five rural, continental US stations with data from 1905 to 2003 was averaged and
    smoothed. The profile indicates that temperatures remain below the average over the first half of the twentieth century.”

    Archibald seems to think the sun will save us from ourselves and with his most recent effort that even if the sun doesn’t step in the carbon isn’t much of a problem anyway.

    Paul Middents

    Comment by Paul Middents — 4 Oct 2007 @ 11:06 AM

  5. I think it is interesting that Archibald had to go back a decade to find a sensitivity estimate low enough to support his assertion. Even Schwartz’s musings wouldn’t do it for him. I suppose it’s an indication of the progress we’ve made if nothing else–now to be a denialist, you have to be not only delusional, but also woefully outdated.

    Comment by Ray Ladbury — 4 Oct 2007 @ 12:23 PM

  6. Archibald’s garbage is not meant to fool science minded people. His article is meant for the lay public to create a sense of doubt and hesitation. This is one of the key principles of propaganda. It does not need to be true, it just needs to sound true, and then repeat it again and again and again.

    I am sure someone is rewarding Archibald for his efforts. Watch for the shrill citations and repititions from the henchmen. I can only hope the organizations behind this get exposed sooner rather than later.

    Comment by Joel Norton — 4 Oct 2007 @ 1:19 PM

  7. My understanding of the climate sensitivity parameter is that the pdf of its estimated value is heavily skewed, with a short, truncated tail to the lower (below mean) side, and a long (very long?) tail to the upper (above mean) side. Furthermore, I thought this was generally accepted amongst climate and other scientists viz. that the parameter occupied a range of possible values, hence a rigorous analysis, with whatever model, should be open enough to show an ensemble of results, generated using different values, with some indication of their relative likelihood. It’s not perfect, I know, but it’s better than saying, in effect, ‘I will assume the parameter has this value, over all other possible candidate values, and not concern myself with other possible model outcomes, however likely they might be …’. Therefore, I wouldn’t attach much credence, if any, to a modelling study that didn’t explore the range of possibilities arising from such uncertainty in parameter values, and particularly in the value of something as crucial as the climate sensitivity parameter, as in this example.

    Comment by Nick Odoni — 4 Oct 2007 @ 1:48 PM

  8. The Stephan-Boltzmann (blackbody) climate sensitivity is about 0.3 deg.C/(W/m^2). Idso claims to have “demonstrated” that it’s 0.1. How is it *possible* for climate sensitivity to be less than the S-B value? Does this require some exotic condition? Idso’s demon? Or is this actually possible for a physically plausible planetary condition?

    [Response: It would require the negative feedbacks to be much stronger than they are. i.e. water vapour would have to go down as temperature rises, low clouds would have to be incredibly sensitive, high clouds not sensitive at all – and forget the ice-albedo feedback! – gavin]

    Comment by tamino — 4 Oct 2007 @ 3:29 PM

  9. A review of one of Archibald’s E&E paper is at titled “The worst climate science paper ever of all time anywhere”

    Notably Archibald even has a 4 part video series on Youtube of his recent presentation to the Lavoisier Society. (Part 1)

    A remarkable effort.

    Comment by Henry Carter — 4 Oct 2007 @ 4:01 PM

  10. Re: #5


    With no disrespect intended as I suspect you know as well as I that old science does not mean bad science. When wishing insights into how CO2 manages to be an effective greenhouse gas I refer to Einstein.

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 4 Oct 2007 @ 5:54 PM

  11. Archibald was doing fine until he introduced his unrealistic value of climate sensitivity parameter. George Bush Sr. once referred to a primary opponent’s ( Reagan’s) economic policy as voodoo economics. Now it seems we have voodoo climatology.
    In comment #2, Ray refers (facetiously) to changing the laws of physics. Something like this has been tried before. In 1997, the Indiana House of Representatives unanimously passed a bill that attempted to legislate a value of pi. The title of the bill was “A bill introducing a new Mathematical truth”(source,”A History of Pi by Petr Beckmann-St. Martin’s Press, 1971, pp 174=177). It never did get through the state Senate and the value was grossly in error.You can’t fool Mother Nature.

    Comment by Lawrence Brown — 4 Oct 2007 @ 6:27 PM

  12. Err, lawrence, when did the Indiana House of Reps try the Pi trick ? Your 1971 reference presumably doesn’t describe an event that happened in 1997.

    Comment by David — 4 Oct 2007 @ 7:22 PM

  13. Lawrence and David, It was 1897, and the culprit was a doctor who calculated 9 separate values for pi. The text of the law was:
    “Be it enacted by the General Assembly of the State of Indiana: It has been found that a circular area is to the square on a line equal to the quadrant of the circumference, as the area of an equilateral rectangle is to the square of one side.
    (Section I, House Bill No. 246, 1897) ”
    I sense a trend here–a learned “man of science” venturing into areas where he is untrained, just as today, most climate skeptics are not climate scientists.

    Comment by ray ladbury — 4 Oct 2007 @ 7:48 PM

  14. Re# 11: Indiana Pi law

    Lawrence, you have a typo. The law was introduced into the House in 1*8*97, not 1997. Wikipedia has a good article on the issue.

    Comment by Rafael Gomez-Sjoberg — 4 Oct 2007 @ 7:58 PM

  15. Thank you, David, Ray and Rafael. I can’t get away with anything around here!(And it’s a good thing too).

    The culprit was indeed a doctor, Dr. Edwin J. Goodman and he hoped to profit from his brainchild as follows,from the preamble to the bill” A bill for an act introducing a new mathematical truth and offered as a contribution to education to be used only by the State of Indiana free of cost by paying any royalties whatever on the same, provided it is accepted and adopted by the official action of the legislature in 1897.” An ex teacher told the legislature “The case is perfectly simple.If we pass this bill which establishesa new and correct(sic) value of pi,the author offers our state without cost the use of this discovery and its free publication in our school textbooks,while everyone else must pay him a royalty.”

    Perhaps those who would repeal the Stefan Boltzmann constant in the formula for the energy radiated by a black body,might try to profit from their findings, as well.

    Comment by Lawrence Brown — 4 Oct 2007 @ 8:40 PM

  16. I had thought the pi=3.0 law was passed and was law for part of a year in Indiana. Maybe not, I guess. (and obviously you meant to type 1897.) I also heard it originated from collusion with the legislature/government and industry — textbooks in this case.

    Comment by Rod B — 4 Oct 2007 @ 8:42 PM

  17. Gavin,

    I tried e-mailing you this but your inbox was full. Apparently the Hudson Institute thinks you, Michael E. Mann, Thibeault De Garidel-Thoron and Stefan Rahmstorf are skeptics.
    LogicalScience Linky

    Comment by Sparrow (in the coal mine) — 4 Oct 2007 @ 9:23 PM

  18. hi everyone

    I’m an observer here at realclimate, with no axe to grind on any ‘debate’. Can someone please post me to any journal articles that calculate a climate sensitivity of 2xCO2 of 3-4 Watts/m2. Please no reference to IPCC documentation, blog entries, etc. but rather to scientific articles.
    I’m a computational neuroscientist and am involved in plenty of dynamic, nonlinear modeling and I would like to follow through the empirically derived steps, even if my knowledge of the physical basis is very limited.

    if anyone could help out, it would be much appreciated
    thanks, Steve

    [Response: Of course: you want the IPCC ar4 report, box 10.2, which summarises things and points you to all the papers you could wish to read -William]

    Comment by Steven — 5 Oct 2007 @ 12:04 AM

  19. Your web interface to modtran is very great. I’ve spent some time messing around with HITRAN data, trying to convince some skeptics that the climate warms with increasing CO2 levels is based on well-established and very boring spectroscopy. As a spectroscopist, I think I get to say that. Anyway, the modtran tool makes it easier. Not that it’s likely to convince my skeptic friends, because I suspect they are in a place where evidence is not likely to make a difference. Nice job pointing out where Archibald went off, too.

    [Response: Thank you. In your playing around with modtran and hitran, keep an eye out for any systematic differences between the two. The modtran model and database were old even when I installed them maybe a decade ago. If you find anything, I’d be very interested to hear. Thanks again, David]

    Comment by Jeff S. — 5 Oct 2007 @ 1:09 AM

  20. Nothing Archibald, or the Lavoisier group says should be taken with any seriousness at all.

    Archibald’s previous “scientific” “climate” paper has been described as the “The worst climate science paper, ever of all time, anywhere.”

    Here’s some of the absolute gold buried within his previous effort:

    – To undertake his computations, which are supposed to indicate a strong correlation of surface temperature to the solar cycle, rather then use world wide temperature estimates (GISS, HadCRU ect…), he uses 5.

    That’s right, 5 stations, all from the South East continental US, all within several hundred kilometers of each other.

    – Strangely enough, each station shows a cooling trend. Hmmmmm…

    – In order to make his “predictions”, of global temperature response from Archibald uses not 5 stations, but 1 station’s data (De Bilt in Holland). 1 data point. Of the thousands available.

    – Archibald uses one data point per solar cycle. Why he does no use annual data for this station is a mystery, but it seems to torture the dat into giving a more impressive looking trend. No formal correlations / R^2 values are reported.

    – He then uses really low estimates of Solar Cycle 24 and 25 to “predict” future world temperatures. Why he chooses these estimates is beyond me. He then confuses solar cycle length and solar cycle strength, but somehow concludes that global temperature will decrease over the next 2 cycles.

    This paper is a load of garbage, and his new work seems to be no different.

    The Lavoisier is an arch, Australian AGW septic group, who even our own (formerly) AGW septic government has tried to distance themselves from in recent years.

    Comment by Chris C — 5 Oct 2007 @ 2:12 AM

  21. The 1.5 degree C IPCC lower end of the range for CO2 doubling climate sensitivity is suspect. Where it is based on models, nearly all the models are biased against solar activity and may be compensating for the missing solar energy with increased sensitivity or feed back to CO2. Furthermore, the models couple CO2 forcing to the whole mixing layer of the ocean while in reality the CO2 wavelengths barely penetrate more than a millimeter and so qualitatively are a complex surface effect.

    Most of the non-model estimates of climate sensitivity are based on the analyses using other forcings such as solar and aerosols, and the assumption that sensitivity to CO2 will be the same, despite the differences in way these forcings couple to the climate system.

    Comment by Martin Lewitt — 5 Oct 2007 @ 4:36 AM

  22. 7 – It’s also worth pointing out that the “climate sensitivity” is a local linearisation of the climate system’s non-linear response to warming.

    So it currently includes a [positive] contribution from the ice-albedo feedback, because our current climate possesses sea-ice that will be melted by a modest increase in temperatures. However, once the sea-ice has melted the contribution from the sea-ice albedo feedback will go, changing the climate sensitivity to further forcing.

    In the other direction, at higher temperatures there is expected to be carbon-cycle feedbacks, that will amplify the warming, so then the climate sensitivty would be higher.

    So climate sensitivity is not quite the be-all and end-all of climate science. In many respects it is an “old” concept, from a time of simpler models, and not one to be too hung up with.

    Comment by Timothy — 5 Oct 2007 @ 6:06 AM

  23. Re: #17

    Sagan was a proud skeptic and wrote an excellent book on the subject, the 2500 scientists who contributed to the IPCC were skeptics, and I like to think I am also skeptical about my own ideas. Unfortunaltely the Hudson Institue (and many others) have perverted the meaning of the word skeptic, the use of the word in their “study” is a (feeble and desperate) attempt to sow doubt by painting things in terms of scientists vs skeptics.

    Sorry, just a pet peeve from an old school “hacker”.

    Comment by Alan — 5 Oct 2007 @ 6:40 AM

  24. Gavin – (My second attempt at a post). I’ve been reading your blog and Steve McIntyre’s as well, for some time now. I’ve recently posted at Climate Audit a complaint about their frequent accusations of fraud on the part of climate scientists. This generated a heated discussion. I’d like to be even-handed here and point out that the comment in #6 does not help any discussion of climate science. I would hope that such posts do not appear in the blog in the future.

    Comment by Erik Ramberg — 5 Oct 2007 @ 7:09 AM

  25. wrt# 24, #6 is quite correct, this is exactly what the skeptical community appear to be doing. To deliberatly misrepresent the data in such a fashion requires either a high level of ignorance or some ulterior motive. I have noticed too many instances of the later and I find it somewhat distastful. The layperson should not be expected to be able to differentate between good science and properganda.

    Comment by Will — 5 Oct 2007 @ 8:37 AM

  26. Martin Lewitt, Now hold on just a bleedin’ minute. The penetration of LWIR into water is immaterial, as by warming the surface, one also warms whatever water the surface layer then mixes with. Mixing occurs on very short timescales. I also see rather strong assertions of bias in your post, but zero evidence to back them up.

    Comment by Ray Ladbury — 5 Oct 2007 @ 8:57 AM

  27. Off topic, but I was wondering if someone more learned than I, with access to research materials could do a post on past instances of ships “crossing the northwest passage.” The skeptical blogosphere is all abuzz with examples of ships making (or attempting to make) the journey, but there is always something fishy about them. Either they used reinforced boats/icebreakers, or it was a treacherous one way journey, or “if only the boats were faster,” or the routes were commercially inviable, or the trip took years to complete, or all fo the above.

    Just a tip.

    Comment by cce — 5 Oct 2007 @ 9:29 AM

  28. Erik – in this instance Archbald is not a climate scientist. Frankly the level of condemnation here compared to the blatant misrepresentation of science is mild.

    Lavoisier Society’s own programme says “David Archibald is a Perth-based scientist operating in the fields of cancer research, climate science and oil exploration. In the cancer field, trials on a formulation he invented with professors from Purdue University are currently underway at Queensland University. In oil exploration, his company, Backreef Resources, is proceeding to a seven well programme in the Canning Basin, Western Australia. Mr Archibald has been an expert witness in the Supreme Court of NSW in the fields of petroleum geology and rolling mills in steelworks.”

    Comment by Henry Carter — 5 Oct 2007 @ 9:45 AM

  29. > Martin Lewitt
    Martin, where are you getting the information you post here? What source are you relying on? A cite or pointer would always be appreciated, or if you’re reporting your own work, please show it.

    Other sources I find don’t match what you believe, for example

    “IR radiation can represent 40%–60% (Mobley 1994) of the total downwelling surface ocean irradiance, it is almost completely (99.9%) absorbed in the upper 2 m of the water column. The
    second process is the heating due to ultraviolet and visible wavelengths (VIS). VIS can penetrate much deeper than IR, and so its role in setting mixed layer depths (MLD) is far more important.”

    See also

    What are you reading that tells you the different information you posted, please?

    Comment by Hank Roberts — 5 Oct 2007 @ 10:16 AM

  30. For David Archibald/Purdue’s cancer pills (“… made from well know vegetables mainly broccoli and chilli …”), he was soliciting people to try them here:

    Comment by Hank Roberts — 5 Oct 2007 @ 11:04 AM

  31. I hve a question from for anyone that understands the greenhouse effect and warming simulations. We are obviously warming now. Is there a top end to the warming trend where we have so much CO2 in the air, more does not increase the greenhouse effect any more? If so what CO2 concentration would that be and what temperature would that take us to?

    [Response: Not really. There are seventy atmospheres of CO2 on Venus, and if you added more, it would warm even further, is my understanding. David


    Comment by Chris — 5 Oct 2007 @ 11:12 AM

  32. Chris, try the button labeled “Start Here” at the top of the page.

    Comment by Hank Roberts — 5 Oct 2007 @ 11:56 AM

  33. Re. Timothy (#22) and the climate sensitivity parameter, I agree totally that we shouldn’t get fixated on it, and I also accept that it’s something of a crude measure, hence the need for modelling studies to include some representation of the parameter uncertainty in the results, rather than sticking to just one value. These semi-empirical models are all prone to model equifinality to some extent, whether the simulated state in question is an end state, or a transient one to which particular scenarios run under different parameter values can converge.

    That said, and despite the crudeness of the sensitivity measure, the long, upper tail on the pdf has to be a matter of concern. On the one hand, it gives those who wish to rebut the idea that Man is changing the climate an excuse to say that our forecasts are too vague to be useful, or to be taken seriously. On the other, it represents a possibility that we are not just in trouble, but that we could actually be in very serious trouble indeed. I know that Mike Schlesinger is going to be working on further studies to see what extra data, and over what timescales, might help us constrain the upper tail, but the possibility arises that no amount of data will do this, or at least, not in time for us to act on it with enough warning to prevent serious problems. One possibility is that the inherent non-linearities in the parameter, which you very rightly highlight, prevent constraint of the upper tail; another might be that the whole climate system gets much noisier and more chaotic, because of extra energy driving the system, so in some wise we lose the signals that might constrain the upper uncertainty. What then, guys, what then?

    Nick O.

    Comment by Nick O. — 5 Oct 2007 @ 1:21 PM

  34. Hank, I tried that, I couldn’t find much about theoretical upper limits to global warming by CO2. I did find one 1985 paper that was pedicting a maximum of 4-5K which seems way too low. Can you give me any more specific references, or possibly to an earlier discussion of this on this site? Thanks

    Comment by Chris — 5 Oct 2007 @ 1:35 PM

  35. 31 Chris
    no there is no top end, but the radiative forcing by CO2 incraeases not linearly proportional to CO2 concentration, but logarithmically to CO2 concentration for more info I recommend previous posts:

    Comment by Andree Henkel — 5 Oct 2007 @ 1:35 PM

  36. I can understand why Archibald, an Australian, would want to deny CC. Australia is perhaps CC’s first big victim among developed nations. It’s really bad there, with worse predicted.

    I developed some survey Qs for a survey course around 1996, actually conducting it on residents in Chicago Collar Counties. Some Qs related to possible GW harms, like “has your house been flooded in the past 5 years”; and some related to GW beliefs. I expected that the flooded would be more likely to believe in GW, but the results were that they were much less likely to believe in GW (holding education and other variables constant). I then reasoned that people who had been harm would much prefer to believe their harm was a fluke (once in a 1000 year thing), and would find it untenable that the same or worse might be coming in the near future.

    Unfortunately I didn’t reach .05 significance, more like .1 or .2 on that (can’t remember). The differences were between the harmed and not-harmed were huge, but the number of respondents was was very low. And that’s because the basment Public Opinion Lab on the NIU campus in DeKalb had been extremely flooded and the lab was only ready at the very end of the semester — flooded in a area that had never before in history experienced flooding.

    Also, when the lab lady was instructing us on how to administer the Qs, I mentioned the flood may have been due to GW. She laughed in my face, but I whipped out a manual I’d just study from IL Natural Resources, a study on GW which predicted that area (among many others) might get flooded….

    Comment by Lynn Vincentnathan — 5 Oct 2007 @ 4:57 PM

  37. Another off-topic comment, but there are likely to be many who will want to obtain a copy of the .pdf file, “The Threat to the Planet: Dark and Bright Sides of Global Warming”, available from Dr. James Hansen’s web site, as the first file listed under the heading Files of Interest:

    (Hope I did this correctly. Hint: could certainly use a preview capability…)

    [Response: Previews re-installed…. let me know if there is a problem – gavin]

    Comment by David B. Benson — 5 Oct 2007 @ 6:29 PM

  38. #35 31 Chris
    “no there is no top end, but the radiative forcing by CO2 incraeases not linearly proportional to CO2 concentration, but logarithmically to CO2 concentration for more info I recommend previous posts”

    Thank you Andree that is what I was looking for.

    Comment by Chris — 5 Oct 2007 @ 6:44 PM

  39. Sorry to be off subject here. But I have two questions. 1) I have seen several places claims that the ENSO has been/ is being changed by AGW. Is there evidence for this? 2) The magnetic north pole is moving towards Russia (through the Arctic). Does this effect currents or climate? Thanks

    Comment by Gary — 5 Oct 2007 @ 7:53 PM

  40. Gary,
    Re 1)–a pretty good, albeit brief discussion here:
    Re 2) Almost certainly not. The geomagnetic field only affects charged or magnetized particles. I suppose that when the field starts to flip, you could see some effect due to solar particle events, but that’ll be the least of our worries.

    Comment by ray ladbury — 5 Oct 2007 @ 8:35 PM

  41. Re the topic, “My model, used for deception”…

    Anyway, you know what the denialists say about models :)

    Comment by Lynn Vincentnathan — 5 Oct 2007 @ 9:10 PM

  42. There are other papers that state that solar cycle 24 will be the start of a Maunder like minimum. For example:…605L..81B

    “We have examined the long-term trends in the solar variability that can be deduced from some indirect data and from optical records. We analyzed the radiocarbon measurements for the last 4500 years, based on dendrochronology, the Schove series for the last 1700 years, based on auroral records, and the Hoyt-Schatten series of group sunspot numbers. Focusing on periodicities near one and two centuries, which most likely have a solar origin, we conclude that the present epoch is at the onset of an upcoming local minimum in the long-term solar variability. There are some clues that the next minimum will be less deep than the Maunder minimum, but ultimately the relative depth between these two minima will be indicative of the amplitude change of the quasi-two-century solar cycle.”

    There are also other papers that have presented arguments for a smaller climatic forcing function.

    I have been following cycle 23 and can attested that it is very unusual. The sun is currently in a spotless state, the solar large scale magnetic field is dissipating. The solar cycle will be 132 months old (11 years) December 31, 2007. If the solar hypothesis is real the cycle will flat line, and the planet will cool.

    I thought with flat lining there would be a 2C cooling and quite rapidly.

    Comment by William Astley — 5 Oct 2007 @ 10:14 PM

  43. Re #35: […but the radiative forcing by CO2 incraeases not linearly proportional to CO2 concentration…]

    But on the other hand, warming of the oceans should release significant amounts of CO2…

    Comment by James — 6 Oct 2007 @ 12:16 AM

  44. Re: #26 and #29

    For a discussion of the ocean skin layer and infrared penetrance see:

    It speaks of micrometers and not millimeters so I was being a little generous. Given such low penetrance, this CO2 radiation will be much more effected by mist, spray and foam, and should more directly impact evaporation than radiation which penetrates 10s of meters.

    What differences in forcings is it safe to ignore in the models? Is radiation which mere micrometer penetrance at a complex ocean surface really equivilent to radiation which can support tropical kelp forests at 200ft depth? See:

    I don’t think, given what we know about the differences, that we can really accept immateriality or equivilence as the null hypothesis. Models based on that assumption have failed to reproduce solar cycle signatures found in the data:

    I quote from the article:

    “Our procedure for the solar-cycle signal yields an interesting pattern of warming over the globe. It may be suggestive of some common fast feedback mechanisms that amplify the initial radiative forcing. Currently no GCM has succeeded in simulating a solar-cycle response of the observed amplitude near the surface. Clearly a correct simulation of a global-scale warming on decadal time scale is needed before predictions into the future on multi-decadal scale can be accepted with confidence.”

    Comment by Martin Lewitt — 6 Oct 2007 @ 6:24 AM

  45. Feeling the need to try to add a little insight, I have been taking a little look at “feedback factors” as in the equation:

    dT(final) = dT(forcing) * f

    or more usefully:

    dT = dF * C * f

    (where T = temperature, f = feedback factor and F a Flux or Forcing and C is the baseline climate sensitivity i.e. for a clear atmosphere)

    and a formula for combining “feedback factors” :

    f = f1*f2 / (f1 + f2 – f1*f2)

    This can be rearranged to give:

    f = 1/ ((1/f1)+(1/f2) – 1) and generalises to

    f = 1/(SUM(1/fi) – (N-1)) where the fi are N individual “feedback factors”.

    Rearranging again we have;

    1/f = 1 – SUM(1-1/fi)

    and substituting: ai for (1-1/fi) and a for 1 – 1/f

    1-a = 1 – SUM(ai)

    This gives an insight into what the “feedback factors” are.

    for now dT = dF/(1-a) * C

    Each ai represents the closure of a proportion of the channel through which passes heat from the surface into space. E.G. the proportion of the bandwidth that is blocked.

    The ai are additive:

    a = SUM(ai)

    with the provision that the closure of a particular piece of bandwidth is not counted twice as where the spectra of two gasses overlap.

    Now dT = dF/(1-a) * C generalises to

    dT = d(F/(1-a)) * C = ( dF/(1-a) + F * d(1/(1-a)) ) * C

    where d(1/(1-a)) = 1/((1-a)^2) * da

    Now dF can be regarded as a true forcing but to make sense F must refer to the total outbound heat flux.

    In general the ai are not constants but are dependent on T and possibly the evolved history of the planet.

    So for an ai(T) that is dependent on temperature we have (in isolation)

    dT = F / ((1-a)^2) * d(ai(T)) * C

    It is important to note that it is the total heat flux F not just the originating forcing component dF that is acted upon. In this way very small changes in ai(T) can give rise to large changes in temperature.

    As it happens the effect of increased CO2 could be regarded as a pseudo forcing (as it is most commonly) or as a small closure of the available bandwidth ie as a component of da. It is perhaps more consistent to regard all changes to the atmospheric content that reduce the available bandwidth in the same way. There is no fundamental difference between the ways that H20 and C02 act as greenhouse gases to imply one should be a forcing and the other a feedback, it is purely a matter of convenience. Also it can be noted that the “feedback factors” are not feedbacks in the strictest sense as they are simply temperature dependent modifications the proportion of the bandwidth that is blocked or as the “resistance” the atmosphere presents to the escaping heat flux.

    We know that the earth is warmer than it would be without greenhouse gases. And we can give some experimental value to (1-a) and the various ai (H20,C02,CH4, etc.). We also have a value for C so some sort of lower limit can be put on the current effective instantaneous Climate Sensitivity that is undeniable. I sincerely hope so.

    I do not have the time to continue this at this moment but I hope this part is of some interest to the circumspect.

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 6 Oct 2007 @ 7:42 AM

  46. Re # 27 cce: Ships crossing the Northwest Passage?
    I don’t who is making that claim, but a recent Reuters news article suggests it is not likely:

    Despite warming, ships to shun Northwest Passage
    By David Ljunggren
    OTTAWA, Oct 3 (Reuters) – While there has been much talk that Arctic trade routes will open up as northern ice melts, shipping companies and experts say using the fabled Northwest Passage through Canada’s Arctic archipelago would be too difficult, too dangerous and totally impractical… Michael Gardiner, assistant commissioner of the Canadian Coast Guard for the Arctic, said there had only been 150 transits in the last 100 years, most by coast guard vessels.
    “The Northwest Passage in its entirety has often been described at shipping conferences … as a rock pile. It’s very tricky navigation through most of it,” he said.
    And if a ship got into trouble the rescue effort would be massively complex and costly, said Bob Gorman of Enfotec, which provides ice navigation services in the Arctic. “It’s just not a route well traveled … there are no tugboats nearby, there are no shipyards nearby, there are no repair facilities, there is no port of safe refuge. You are really out in the wilderness,” he said. …

    Comment by Chuck Booth — 6 Oct 2007 @ 11:29 AM

  47. As a layman reading Alexander’s paper I thought it was phrased argumentatively and could lead to ad hom’s rather than examination of his ideas.

    Alexander’s Figure 12 (showing A correlation between temperature and solar cycle length – rather than amplitude) seemed the key point of the paper, on which his predictions are based. The question: is this spurious or have others noted this correlation for other locations? Seems a basic way to test the main idea in the paper without getting sidetracked on other issues.

    Also, his Figure 10 shows solar cycle amplitude which, by eye, seems to correlate somewhat with known temperature trends. I thought it would be helpful to have a plot of solar cycle length superimposed on this figure – is this available somewhere? That is, does solar cycle length correlate with the following solar cycle amplitude?

    Comment by John M — 6 Oct 2007 @ 12:57 PM

  48. Why doesn’t increased water vapor lead to decreased insolation?
    Several of the absorption bands seem not to be saturated.

    Comment by lgl — 6 Oct 2007 @ 1:26 PM

  49. [[Where it is based on models, nearly all the models are biased against solar activity]]

    In what way? All the models I’m familiar with take solar activity into account.

    Comment by Barton Paul Levenson — 6 Oct 2007 @ 1:37 PM

  50. This is in response to Alexander Harvey in #44.

    You are clearly familiar with some of the aspects which are involved and I appreciate your efforts.

    I will set aside the mathematics at this time – although someone else may be better equipped to deal with it than I.

    However, I believe there are a few issues worth pointing out.

    First, you state in #44:

    There is no fundamental difference between the ways that H20 and C02 act as greenhouse gases to imply one should be a forcing and the other a feedback, it is purely a matter of convenience.

    There is a fairly big difference between water vapor and carbon dioxide: water vapor doesn’t stay in the atmosphere for very long – perhaps a few weeks. It falls out in the form of rain and snow. As such a pulse of water vapor won’t stay in the atmosphere long enough to raise the temperature significantly and the original equilibrium (prior to the pulse) will be quickly re-established. However, carbon dioxide stays in the atmosphere for a very long time. In fact, a substantial percentage of a pulse of carbon dioxide will remain in the atmosphere even a hundred thousand years. For the original equilibrium to be reestablished, you have to have mineralization – and that takes a long time.

    As long as there is more carbon dioxide in the atmosphere than before, it will reduce the percentage of thermal radiation which is able to leave the atmosphere, which means that the climate system must heat up if the rate at which energy leaves the climate system is to equal the rate an which energy enters the climate system. Since it stays in the atmosphere longer, it will raise the temperature gradually over the decades. As the temperature rises, water vapor evaporates at a higher rate, raising the water vapor content of the atmosphere, further amplifying the the increased greenhouse effect of the additional carbon dioxide.

    Second, carbon dioxide isn’t always considered a forcing – and I believe this is somewhat in step with one of the points in your post – although there are certainly times even in the paleoclimate record when it has been so. (A good example would be the Permian Triassic extinction which was driven largely by the eruption of a supervolcano in Siberia, raising the CO2 levels to around 3000 ppm.) Sometimes increased insulation due to a periodic shifting of the earth’s orbit towards the sun will raise the temperature first and the carbon dioxide will follow – with higher temperatures reducing the amount of carbon dioxide which the ocean will have the capacity to hold – and the amount of carbon dioxide which plants are able to absorb given droughts. Another may be the raising of the temperature of permafrost which will release methane and carbon dioxide, increased moisture in the polar altitudes resulting in more methane in growing bogs, but there are other feedbacks to the carbon cycle.

    The feedbacks from the carbon cycle may become important – inasmuch as higher temperatures brought on by our own anthropogenic emissions of carbon dioxide may raise temperatures enough that it will cause the climate system to start emitting more carbon dioxide of its own. Some of those feedbacks seem to be kicking in a little already.

    What constitutes a forcing? Anything which reduces or increases the rate at which energy leaving the climate system is not equal to the rate at which energy enters the climate system – and does so long enough that the equilibrium temperature has the chance to shift.

    Second, you state in #44:

    We also have a value for C so some sort of lower limit can be put on the current effective instantaneous Climate Sensitivity that is undeniable. I sincerely hope so.

    There are a couple of problems here, one related to the physics and one related to the nature of science itself.

    First the physics. There is no such thing as an instantaneous climate sensitivity. More greenhouse gas (whether it is carbon dioxide or water vapor) will reduce the ability of thermal radiation to leave the atmosphere, but it will not instantaneously raise the temperature. That takes time – as it will take time for the surface to rise in temperature – even before one takes into account any feedbacks.

    Second, nothing in science is undeniable. Leave the “undeniable” to Descartes. What science deals with is the cummulative weight of the evidence – but if some skeptic is willing to snuggle up to the belief that everything that they see and remember was put there five seconds ago, they can certainly do so. Regardless, we are pretty confident that the Charney climate sensitivity is roughly three degrees Celsius. (We have about 400,000 years of climate data to back that up.) However, this is in the short-run.

    We call this the Charney climate sensitivity, because it is essentially the case considered by Charney (1979), in which water vapor, clouds and sea ice were allowed to change in response to climate change, but GHG (greenhouse gas) amounts, ice sheet area, sea level and vegetation distributions were taken as specified boundary conditions.

    Global Warming: East-West Connections
    James Hansen and Makiko Sato

    According to Hansen, long-term is more like six degrees. Then of course there is the feedback from the carbon cycle itself.

    One more point…

    This is actually a little earlier in your post, but it is also a little more technical, so I am putting it off to last.

    You state in #44:

    Each ai represents the closure of a proportion of the channel through which passes heat from the surface into space. E.G. the proportion of the bandwidth that is blocked.

    The ai are additive:

    a = SUM(ai)

    with the provision that the closure of a particular piece of bandwidth is not counted twice as where the spectra of two gasses overlap.

    The problem is that even if radiation is absorbed, lets say in the lower troposphere by water vapor, an equal amount of radiation will be emitted by water vapor in the same band. Some will be upwelling, some will be downwelling. For that which is upwelling, if the bands overlap with carbon dioxide in the upper troposphere or lower stratosphere where the atmsophere is dry, it will be absorbed and an equal amount will be reemitted in the same band. Likewise some of the emission by carbon dioxide will be upwelling and some will be downwelling. Whenever the thermal radiation is downwelling, it will tend to increase the greenhouse effect.

    I suspect the problem here is that you are thinking of greenhouse gases as blocking thermal radiation such that once the radiation is absorbed there isn’t any reemission. But they don’t block – they absorb and emit – in both directions. Without the greenhouse gases thermal radiation would simply be radiated into space and there would be no downwelling of thermal radiation – just the absorbtion of sunlight.

    But greenhouse gases are a part of the atmosphere and render it opaque to thermal radiation – which means that some will be downwelling. It is the downwelling that reduces the rate at which energy is leaves the climate system until the temperature of the system rises enough that the rate at which energy enters the system equals the rate at which energy leaves the system – and a new equilibrium is established.

    However, overlapping bands in the lower troposphere where water vapor dominates will keep carbon dioxide from absorbing any significant amount of radiation – in the lower troposphere itself. This is where a band will be saturated by a given greenhouse gas – and one needs to avoid double-counting.

    Anyway, thank you for throwing some light on this. Hopefully I have managed to illuminate things a little as well.

    Comment by Timothy Chase — 6 Oct 2007 @ 4:12 PM

  51. Timothy,

    My thanks go to you for taking the trouble of replying in such detail.

    I shall try to respond in the same manner when I can. I have a fair amount on just now but hopefully this thread will stay alive long enough to offer me such an opportunity.

    For now just my thanks must suffice.

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 6 Oct 2007 @ 6:20 PM

  52. #47, the water (and CO2) bands seen in the solar visible and near IR are called vibrational overtones. If molecular vibrations are harmonic, the nuclei moving like a perfect spring, only transitions between the closest vibrational levels are allowed. As real springs, molecular vibration is anharmonic. It is this anharmonic component that makes allowed vibrational transitions which take you from one vibrational level to much higher ones. These are VERY weak.

    The water vapor bands that are most important to the greenhouse effect are those that result from rotational transitions (changes in the rotational quantum numbers) in the IR, and somewhat the bends. These are saturated in the CO2 sense.

    A more detailed explanation would be, well much more detailed, so perhaps this is not the place.

    Comment by Eli Rabett — 6 Oct 2007 @ 9:00 PM

  53. #44, Alexander Harvey says: “There is no fundamental difference between the ways that H20 and C02 act as greenhouse gases to imply one should be a forcing and the other a feedback, it is purely a matter of convenience.”

    My understanding of how feedback and forcing are used, is that forcing is external to the climate system, as for example solar insolation. If, for example, CO2 is added to the system from burning fossil carbon, it is being introduced from a source isolated from the climate system in any meaningful sense and is a forcing. If it is added by warming of the oceans, then it is being added from inside the system in response to temperature increase and is a feedback. To paraphrase, a feedback in one situation is a forcing in another, but it is either or, not both at the same time.

    Comment by Eli Rabett — 6 Oct 2007 @ 9:04 PM

  54. lgl–most incoming solar radiation is in the visible. Water would absorb what is in its absorption band, but once excited, it would tend to relax collisionally, so that energy would mostly go into heating the atmosphere anyway. Still, the outgoing flux of LWIR is much higher than that of incoming LWIR.

    Comment by ray ladbury — 6 Oct 2007 @ 9:07 PM

  55. Re 44: I believe you can rearrange the final equation into a simpler form:
    N = On(e.Se/Ns^E)

    Comment by bobn — 6 Oct 2007 @ 9:50 PM

  56. Australia is about to have a Federal Election and John Howards Liberal Party has a bunch of so called intellectuals – Archibald – who will say anything , regardless of the consequences, to get their party back in power. Politics has a lot to answer for in Australia in regards to climate change, especially if you would like to live in a world of 1000ppm CO2, as some buisiness men think would be pretty cool.

    Comment by Simon Edmonds — 7 Oct 2007 @ 6:20 AM

  57. Timothy (50), a clarification please.

    Does upwelling “re-emission” from water vapor really get absorbed by high altitude CO2? Why would H2O radiate, not in its natural spectra, but in CO2s spectra (other than the minor overlapped bands)? [I’m not sure if this would alter your basic premise, however.]

    Isn’t there some point, eventual equilibrium of sorts, when greenhouse gases do “block” (absorb without re-emission) terrestrial radiation? Otherwise we would not see any vacant spectra in the, say, satellite imaging of terrestrial radiation, would we?

    A helpful post. Thanks. You, too, A. Harvey.

    Comment by Rod B — 7 Oct 2007 @ 11:10 AM

  58. Re 54#
    “most incoming solar radiation is in the visible”, well – more 50/50 I would say. But yes, the energy would heat the atmosphere and a lot of that energy would radiate back to space and not reach the surface. This should give less heating of the surface and less outgoing LWIR.
    In addition the H2O absorption bands in the LWIR seem to be much more saturated that those in the solar IR spectrum.
    If more of the insolation is absorbed in high troposphere the increase in GHG should also make it more difficult for that energy to reach the surface.
    Thirdly, increased evaporation brings more heat to “high up” (how high?). The GHG would not influence the upwelling but would reduce the downwelling IR, right?
    I see from the radiation budget that the absorbed solar, evapotranspiration and outgoing thermals add up to about 170 W/m2. I don’t know how much of this is radiated back to ground but I would assume that this incoming radiation also face an increased greenhouse effect, which should then have a cooling effect.
    To get to the point. I am looking for a paper (free on the web of course) where these effects are described/estimated and how they are treated in the models.

    Comment by lgl — 7 Oct 2007 @ 1:53 PM

  59. In answer to the question, “who are the organizations that continue to fund baseless attacks on climate science?” here are some of the main players:

    The American Petroleum Institute:

    The Edison Electric Institute:

    In the past, the now-disbanded Global Climate Coalition was the front organization for fossil fuel interests who want to prevent any reductions in fossil fuel use. Essentially, these interests know that renewables are simply less profitable and will be expensive to produce, requiring massive amounts of investment in production facilities and electrical grid infrastructure. It’s cheaper to spend hundreds of millions on slick PR campaigns designed to create doubt in the public’s mind over climate science than it is to replace fossil fuels with renewables.

    Essentially, that’s the problem. An 80-90% reduction in CO2 emissions really requires an 80-90% reduction in fossil fuel sales. That energy demand must be met with real renewable sources, primarily wind and sunlight, and energy efficient technology. That requires replacing the existing trillions of dollars of fossil fuel infrastructure with trillions of dollars of renewable infrastructure, and nobody seems to want to spend the money. Vast sums will have to be spent to create a renewable-energy based infrastructure – which means a lot of economic activity, but which also means turning the global economic order upside down. No oil-selling country or corporation on the planet wants to see U.S. energy demand drop, regardless of their political viewpoint.

    Across the U.S. right now we have a wave of ‘feel-good’ proposals, with local and national politicians pledging their green values left and right – but when it comes to funding real changes, it’s just not happening. Fossil fuel companies and government economists are still working on the assumption that U.S. fossil fuel demand and consumption will continue to increase over the next twenty years.

    Taking action on global warming is now seen as politically popular, so we’re seeing a lot of rhetoric – but no real large-scale changes in the energy picture have been proposed by politicians to date.

    Comment by Ike Solem — 7 Oct 2007 @ 2:19 PM

  60. lgl, OK, think about this. First, the amount of energy at wavelengths shorter than the absorption bands of the GHGs is well over 50%. Second, warming the atmosphere does heat the surface, since it means that the net outgoing radiation is less. Yes, the ghgs do absorb in their lines, but they don’t care whether radiation is outgoing or incoming–and there’s a whole lot more outgoing LWIR than incoming (look at a spectrum of Earth’s thermal radiation). And yes, water vapor does transport energy into the lower troposphere. However, it drops it there. The only way for it to escape is via outgoing IR radiation. I would strongly recommend that you get the science of the greenhouse effect under your belt before tackling the scientific literature. Check out the text by Ray Pierrehumbert

    Comment by ray ladbury — 7 Oct 2007 @ 2:55 PM

  61. Thanks Ray, at first it looked quite promissing.
    5.10 Effects of atmospheric solar absorption . . . 198
    but where is it?
    Ah.. “Chapter 5, is about 3/4 complete now”
    Please hurry Pierrehumbert! I’m waiting for this.
    Meanwhile, just to make sure, are you really saying that none of the heat brought to the atmosphere by thermals and solar absorption is radiated back to the surface? And if it is, why do not GHGs have any impact on this radiation?

    Comment by lgl — 7 Oct 2007 @ 5:19 PM

  62. Further to #56: Guy Pearse, a former advisor to Howard, has written a book about Australian politics and climate change:

    “…He reveals that the government has no plans whatsoever to reduce Australia’s emissions, and explains why this is bad for Australia’s economy. He exposes a prime minister wilfully blind to Australia’s real Interests – a man who has allowed climate change policy to be dictated by a small group of Australia’s biggest polluters and the lobbyists they fund…”

    And a couple of articles about the book and the politics:

    I think Howard, Bush and Harper all sing from the same songbook.

    Comment by Holly Stick — 7 Oct 2007 @ 5:25 PM

  63. Ray> First, the amount of energy at wavelengths shorter than the absorption bands of the GHGs is well over 50%.

    Still, looking at the solar spectrum:
    it appears that a lot of incoming solar energy between 900 and 2000nm is absorbed by water vapor. Does anyone know if this negative feedback from water vapor increasing with temperature is included in the climate models?

    [Response: It actually isn’t much of a feedback (since it mostly intercepts energy in the troposphere that would have been absorbed by the surface), and yes, this is included in most GCMs with reasonable radiation models. – gavin]

    Comment by Steve Reynolds — 7 Oct 2007 @ 6:59 PM

  64. Ups, I made a mistake in 61#
    I should of course have said “to the atmosphere by thermals and evaporation” not “to the atmosphere by thermals and solar absorption” You were quite clear about the solar.
    I have this notion that heat released high up in the atmosphere will not warm the planet as much as if it was released very low in the atmosphere, maybe this is where I’m taking the wrong path?

    Comment by lgl — 8 Oct 2007 @ 1:24 AM

  65. Very enlightening discussion. Many thanks. I really question Archibald’s methods and so should you all.

    Comment by petefontana — 8 Oct 2007 @ 2:44 AM

  66. [[Isn’t there some point, eventual equilibrium of sorts, when greenhouse gases do “block” (absorb without re-emission) terrestrial radiation? ]]

    They can’t absorb without emitting.

    Comment by Barton Paul Levenson — 8 Oct 2007 @ 5:32 AM

  67. Re: #59 Ike, “Fossil fuel companies and government economists are still working on the assumption that U.S. fossil fuel demand and consumption will continue to increase over the next twenty years.”.

    Sounds plausible, however doesn’t the reality of Peak Oil, begin to pull the rug out from under this premise? Or does oil start to become a non issue in the context of the bigger picture when taken together with natural gas and coal?

    My personal hunch is that as technology progresses it becomes increasingly feasible for larger swaths of the general population, to become completely energy independent, thereby breaking the the energy companies monopoly.

    I think this is the scenario that they dread the most and will surely fight to the death to maintain their lucrative status quo regardless of the consequences.

    Comment by Fernando Magyar — 8 Oct 2007 @ 5:41 AM

  68. “Peak Oil” just means “invest in oil companies”. What they sell will just keep getting more valuable.

    Demand hasn’t slacked much with the increases in price so I don’t have much faith in alternate energies saving our bacon.

    Comment by Jeffrey Davis — 8 Oct 2007 @ 8:19 AM

  69. Demand has continued to soar despite the higher prices. The demand for energy has never been higher than it is right now. The higher prices support the more costly refining that once precluded bringing certain types of fossil fuel reserves into production.

    Comment by J.C.H. — 8 Oct 2007 @ 10:31 AM

  70. Barton (66), I understand the logic of that, but the puzzle is: a bunch of radiative power in a certain band leaves the earth’s surface, but is not much seen at the top of the atmosphere. Where did it go??

    Comment by Rod B — 8 Oct 2007 @ 10:45 AM

  71. Rod, the ‘band’ refers to counting a lot of photons in arange of energies. It’s not a unique entity that persists, it’s a measurement.

    Sunlight warms the Earth. The solids heat up. The molecules in the solid Earth aren’t free to bounce around, they’re pulling and tugging at each other but (short of boiling to vapor, for example) don’t break apart and float freely. All the pieces are moving, the motion of the atoms produces photons. The range of motion isn’t in discrete steps because everything’s tugging on everything else in a solid, so any range of motion possible can produce a photon of that amount of energy. From Earth in sunlight, it’s the ‘infrared band’ that’s produced.

    That “band” is like a battle plan, it does not survive first contact with the enemy — the next molecule that any of those photons hits absorbs its energy. Photon’s _gone_.

    On average.

    Some photons from the ground, and from low clouds, and from water vapor in the atmosphere, do make it all the way out into space — you can look at the satellite photographs in the infrared bands. Compare those wavelengths to the wavelengths in which our atmosphere is less opaque to infrared.

    But on average, in the dense lower atmosphere, a photon hits a molecule; the molecule’s energy increases, in some vibrational mode, while also transferring energy among those modes internally and banging into other molecules. The original photon no longer exists, it’s a bookkeeping entry for transfer of energy.

    Higher in the atmosphere the gas molecules are more widely separated. While they’re not banging into one another, each one can emit photons at the specific wavelength defined by the ways its atoms can vibrate.

    We talk about an average altitude (6 km and rising) where — on average — photons interact less often and more of them escape into space, removing energy from the planet.

    So — there’s where your “band” goes.

    Imagine a pool game in which, half the time, your white cue ball would change to another ball on impact, and if a couple or three of the other balls displaced from the rack happened to hit the right way, one of them would turn into another white cue ball.

    Comment by Hank Roberts — 8 Oct 2007 @ 12:27 PM

  72. lgl,
    Once energy is absorbed by either the atmosphere the ocean or solid Earth, it is part of the system that determines climate. The only way it can escape is as radiation–and because of the temperature of Earth, mainly IR radiation. Rod, you asked where the energy goes. It goes mainly into thermal excitation of molecules in the atmosphere and also on Earth’s surface–at least until the temperature rises enough to restore equilibrium where incoming energy equals outgoing energy.

    Comment by ray ladbury — 8 Oct 2007 @ 2:10 PM

  73. Igl (#64) wrote:

    Oops, I made a mistake in 61#
    I should of course have said “to the atmosphere by thermals and evaporation” not “to the atmosphere by thermals and solar absorption” You were quite clear about the solar.

    I have this notion that heat released high up in the atmosphere will not warm the planet as much as if it was released very low in the atmosphere, maybe this is where I’m taking the wrong path?

    Actually this much is right.

    In terms of optical thickness, longwave’s which are at a greater altitude have considerably less “distance” to travel to reach space. And the path will be one of multiple absorptions and emissions is a random walk. Therefore that which is closer to the surface is much more likely to return to the surface, and that which is closer to space (in terms of optical thickness) is more likely to make it to space.

    But there are two qualifications to keep in mind. First, optical thickness is roughly distance, but with lower atmospheric density – which decreases exponentially with altitude, etc along the longwave’s path taken into account. In fact, optical thickness is actually dimensionless. Second, one can’t actually treate the energy as a single photon since the energy gets lost to collisions, spread out between different molecules in still other collisions, etc. But an early, first conceptual approximation may be thought of as a single photon or parcel of energy.


    Anyway, if you haven’t already, I would check your question in 61 against Ray’s comment in 60. There is still a great deal of longwave being radiated by greenhouse gases going to surface. However, when he states that that which is absorbed coming up from the surface tends to be lost in collisions (see 54), this is only because the time between collisions for any given molecule tends to be much shorter than the half-life of an excited state. About a millionth of the timespan. As such, when a molecule radiates a photon, this is due to the molecule having received energy through collisions in the same way that molecules lose energy due to collisions.

    Now why don’t the molecules lose this energy before they emit – given the timespans?

    Most actually do lose energy that way.

    But why do any radiate.?

    Because we are dealing in half-lifes. The molecules have no “knowledge” of how long they have been in an excited state. They spontaneously decay. As long as a certain number are in an excited state at any given time, a certain number will undergo spontaneous decay over a given period. The coins get passed around, but whereever they are, they keep getting tossed – and some come up heads.

    Hope this helps…

    Comment by Timothy Chase — 8 Oct 2007 @ 4:13 PM

  74. Dear bobn,

    Re: #55

    I always welcome constructive criticism.

    When you have some, do please post it.

    FWIW the origin of the equations is not my work and has been around in the literature for at least 20 years.

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 8 Oct 2007 @ 4:48 PM

  75. Re 64. lgl, Your intuition is mainly correct, but you need to define what you mean by “high up in the atmosphere”. Essentially that means that the optical path of the photons is longer than the residual distance to the top of the atmosphere. That depends on the density of molecules that can absorb the photon on its upward path. As we raise the ghg content of the atmosphere, we effectively raise the altitude at which IR photons are able to escape, meaning that less energy is able to rise up that high. Thus the part of the atmosphere from which radiation can escape is colder and so radiates less, meaning more energy stays in the climate system. That’s one way to look at it–essentially the same as that in “A Saturated Gassy Argument”.

    Comment by ray ladbury — 8 Oct 2007 @ 7:30 PM

  76. Barton, Ray, Hank, Timothy, et al: I may be getting it. I’ll try a simple example, and see if it works. The 15um band radiates a bunch from the surface. Spectral analysis shows about (eyeballing it — assume for discussion) 5% transiting and leaving the atmosphere. I assume this 5% either made it out directly, or with the absorption – many collisions – secondary emission chain of events (and maybe going through that chain many times). The other 95% will get absorbed and, following roughly the same general process above, 1) re-radiate directly back to the ground (a very tiny portion of the 95%), 2) pass energy to other molecules through multiple collisions and finally end up adding to the “steady state” kinetic energy of atmospheric molecules and heat the atmosphere (bigger than #1, but still small), 3) go through the process chain above and finally break the chain(s) by emitting back to the surface (my guess, the vast preponderance of the 95% that didn’t make it out). Though I’m not sure why the downward re-emission doesn’t get absorbed by other greenhouse gases before it reaches the ground. Or… maybe it does and just keeps going through the cycle chain numerous times with the overwhelming probability that it will finally go down to the surface rather than up and out…???

    Is this, while oversimplified, generally close?

    Comment by Rod B — 8 Oct 2007 @ 9:12 PM

  77. I know it is off the topic, but apparently IPCC have underestimated the level of CO2e in the atmosphere…

    Any comment on this from RC?

    [Response: This is very confused and misleading. The AR4 WG1 report showed that the positive forcings from WM-GHGs were around 2.7 W/m2, which is 455 CO2_equivalent, but the climate basically only cares about the total forcing – which includes cooling from aerosols and the effects of soot and ozone and solar and the like. The more relevant net forcing is estimated to be around 1.6 W/m2 (which is about 380 CO2_e). Statements like Flannery’s implying that the IPCC doesn’t know what’s in it’s own reports or that suddenly there are more GHGs than we thought are just silly. He should know better. The situation is bad enough without the exaggeration. – gavin]

    Comment by Tosh — 8 Oct 2007 @ 10:35 PM

  78. This question is climate related, but not related to this article:

    Some skeptics point out that man-made emissions account for only a small percentage of total CO2 emissions into the atmosphere; the rest being from natural sources. I’m finding this hard to reconcile with the large CO2 jump following 1975. Are they saying that only 3-7% of the 380ppm C02 concentration in 2007 is man-made? Which would mean that a large natural CO2 increase occurred following 1975. Am I missing something here? Someone explain this to me. What is meant in these statements?

    Comment by John Galt — 8 Oct 2007 @ 10:56 PM

  79. thanks Gavin, I thought is sounded strange… I’ve found he gets quite a bit wrong on energy issues so the alarm bells usually go off when he comes out with this sort of stuff. I guess it shows the poor state of the debate in our country when he is considered one of the ‘front men’.

    To the rest of the world… please don’t judge us because we are Australian, most of us are ashamed enough already!

    Comment by Tosh — 9 Oct 2007 @ 12:21 AM

  80. Rod, maybe David Archer can comment — someone who actually understands MODTRAN and the math, I hope, will. I think words are just approximations at best, and I don’t pretend to be able to handle the math.

    Comment by Hank Roberts — 9 Oct 2007 @ 1:02 AM

  81. Re: #78 (John Galt)

    You’ve been fed a classic piece of denialist propaganda. What they omit to mention is that natural CO2 emissions to the atmosphere (from oceans, biosphere, etc.) is balanced by natural absorption (by oceans, biosphere, etc.). That’s why, for over 10,000 years, CO2 concentration was reasonably stable at about 270 ppmv.

    You may even hear the false claim that more CO2 is emitted by a large volcanic eruption like Mt. Pinatubo or el Chicon, than all human activity since the beginning of time. This is just plain false. CO2 emission from large volcanos is measured in megatons, but the CO2 emissions from the U.S. alone, in one year alone, count in the gigatons. And of course, 1 giga = 1000 mega.

    The truth is that all the rise in CO2 concentration since pre-industrial times is due to human activity. This is beyond doubt; the carbon in fossil-fuel CO2 has a different “isotopic signature” from that due to natural emissions, and the changing isotopic composition of atmospheric CO2 is a “smoking gun” proving that the increase is from fossil fuels.

    Not only is this claim junk — it’s not even very good junk.

    Comment by tamino — 9 Oct 2007 @ 1:07 AM

  82. Oh, further for Rod, this is another diagram from the same source Timothy Chase pointed to in the parallel conversation (this thread seems more the right place for it). Your description above fits this, I think?

    Comment by Hank Roberts — 9 Oct 2007 @ 1:07 AM

  83. John Galt, look up “biogeochemical cycling” to answer the point about humans adding only “a small percentage of total CO2 emissions” — what is happening that changes climate is that CO2 from fossil fuels that doesn’t all get cycled by natural processes (about half the total produced by burning fossil fuels so far is still in the atmosphere, the other half did get taken care of by nature). The “natural carbon sinks” only accept so much — the rest accumulates fast in the atmosphere and won’t get taken care of by natural cycling for some centuries. And if the natural processes get overloaded and quit working, then the excess will accumulate faster.

    The ‘start here’ link at top of page will help with the basic questions like this.

    Comment by Hank Roberts — 9 Oct 2007 @ 1:17 AM

  84. thanks Gavin, I’ve written to the ABC and asked them to clarify with Mr Flannery and if appropriate, issue a pulic retractment.

    Comment by Tosh — 9 Oct 2007 @ 3:29 AM

  85. Re #78 The pre-industrial level of CO2 was measured around 1900 at 280 ppm, and that value has been confirmed by the analysis of ice cores. Today the level of CO2 is at 380 ppm, an increase of almost a third.

    If you go to the NASA site you can see the latest measurements of atmospheric CO2 taken on top of Manua Loa, in the centre of the Pacific. See

    What the skeptics are arguing is the the change during one year, as shown by the red curve,is much greater than the net change each year shown in the black curve. The seasonal change in CO2 is caused by the blooming and decay of vegetation on the continents, which are mainly in the northern hemisphere. That has a net effect of zero on the annually averaged CO2 level.

    Or it would have, but with the burning of the rain forests in fact there is more CO2 released into the atmosphere than the pasture lands that replace them can absorb. So the rise in CO2 and the resulting global warming is not just a result of burning fossil fuels. Land use change is also having a not insignificant effect.

    Comment by Alastair McDonald — 9 Oct 2007 @ 4:36 AM

  86. Re #78

    I should have written a NOAA website not NASA, but it is no less authoritative.

    Comment by Alastair McDonald — 9 Oct 2007 @ 4:41 AM

  87. Re 78:

    Each year vegetation takes up ~110 gigatons (1 billion metric tons) of carbon from the atmosphere through photosynthesis. And each year, plants, animals, and microbes respire about ~110 gigatons of carbon back in to the atmosphere. Over the last several hundred millions, some amount of carbon on the order of ~5000 gigatons wasn’t respired back to the atmosphere but trapped in the lithosphere becoming what we know as fossil fuels. Our civilization is now burning fossil fuels, emitting some of that carbon back in the atmosphere on the order of several gigatons per year.

    So to answer your question, yes, annually the amount of carbon released by burning fossil fuels is only 3-7% of that respired (“natural emissions”) by the biosphere. The important distinction to be made is that the carbon cycle without fossil fuel emissions would be much closer to a steady-state. That is the amount taken up by photosynthesis is very close to the amount respired.

    So, each year we are adding a few gigatons of carbon to the atmosphere, even though the anthropogenic carbon emissions are small compared the natural fluxes. This can all be solidly demonstrated by measuring the changes in the isotopic composition of atmospheric carbon dioxide. I refer you to the some of the great climate science links provided by Real Climate in the panel above on the right, if you want to learn more.

    Comment by Ryan Pavlick — 9 Oct 2007 @ 5:49 AM

  88. “John Galt” posts:

    [[Some skeptics point out that man-made emissions account for only a small percentage of total CO2 emissions into the atmosphere; the rest being from natural sources. I’m finding this hard to reconcile with the large CO2 jump following 1975. Are they saying that only 3-7% of the 380ppm C02 concentration in 2007 is man-made? Which would mean that a large natural CO2 increase occurred following 1975. Am I missing something here? Someone explain this to me. What is meant in these statements?]]

    The amount emitted by human technology in one year is small compared to the total out there. But it has been emitted for many years now. About 28% of the CO2 currently in the air is manmade.

    The human amount is small compared to the natural emissions as well, but the natural emissions are largely matched by natural absorptions. For example, the oceans emit about 90 gigatons of carbon every year, but absorb 92 gigatons. It’s the human emissions that are driving the net increase every year, just like a small trickle into a bathtub that is full to the top will cause an overflow. The comparison of human emissions to natural emissions is disingenuous, because natural emissions are largely balanced by sinks and human emissions are not.

    Comment by Barton Paul Levenson — 9 Oct 2007 @ 6:04 AM

  89. Timothy,

    Re: #50

    I think have found a copy of “Charney J 1979 Carbon Dioxide and Climate: A Scientific Assessment” and I shall read it before making any comment.

    I am aware of some of the mechanisms involved in the absorption and emission of radiation in the atmosphere. I will if I may suggest a modification to that which you wrote.

    In that absorption does not necessary equal emission. It depends on the temperature. For instance in the H20 bands there is a net flux in the direction of decreasing temperature. Eventually this turns into a net outboud flux at the TOA.

    You can get a feel for this from MODTRAN if you select low altitudes and select “looking up”.

    In the “looking up” mode it gives you the “Path Length Radiance” e.g the component that comes from the atmosphere not directly from the surface.

    At low altitudes e.g. .01km the band (wavenumber 100-400) “shines” with a temperature of ~288K i.e. surface air temperature.

    At 1 km it shines with a temperature of ~280K.

    At 4 km at around ~260K.

    The actual temperatures that MODTRAN assigns to 1km and 4km are higher 281.7K and 262.2K.

    If you do the same “looking up” you get very similar radiation temperatures. The band is close to thermal equilibrium which is I think what you were describing. But as there is a temperature gradient so there is a net flow upwards.

    In these bands the “direct” radiation from the Earth’s surface is blocked. The downflow and upflow are all but identical at low altitudes. From the point of view of the ground surface that band is effectively closed.

    This could lead to a paradox as at TOA this band radiates with strengths between the yellow and light blue lines ie an equivalent temperature of between 220K and 240K. This is more or less a net outbound flux.

    From MODTRAN we have a net upward flux at the surface that is less than half the TOA outbound flux. I think that this is the sort of difficulty that you are aware of.

    It would be much more accurate to not use the word blocked but to say that the “blocked” bands were “thermal bands” and the clear bands were “radiative bands”. As an approximation the “thermal bands” radiate at around 220K and the clear bands at around 288K. The fourth power of (288/220) is ~1/3 so a significant reduction in outbound radiation results from “blocking” a band.

    A word of caution MODTRAN seems to have a rule that the temperature at the 12km altitude is fixed as is the lapse rate.

    Now as more greenhouse gases enter the atmosphere due to outputs of CO2, CH4 and the effect of rising temperature on H2O vapour. The “thermal” output will become increasingly important and the direct radiative component less so. This will mean that the upper troposphere temperature will become increasingly important as a means of removing heat from the system.

    I for one should like to know if the assumption of constant lapse rate and a constant 12km temperature that “seem” to be built into MODTRAN are realistic.

    I do not know the sensitivity of outbound radiation to temperatures in the upper troposphere but based on MODTRAN my best guess is that a temperature rise of 1C might contribute 0.75 W/m2.

    On the other hand increasing greenhouse gases will I think mean that more energy would need to be supplied to the upper atmosphere to power the thermal radiation output there. These are areas that I know little about but would be interested to know more.

    I will write again regarding your other points when I can.

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 9 Oct 2007 @ 7:30 AM

  90. Re Myself #79

    I have always used this interface to MODTRAN.

    If you want the “lookig up” and some other features you may need to do the same.

    Comment by Alexander Harvey — 9 Oct 2007 @ 7:39 AM

  91. re #75. Ray Ladbury states that “as we raise the ghg content of the atmosphere, we effectively raise the altitude at which IR photons can escape.”

    As I understand it, this altitude or level is referred to as the effective radiating level and is measured by examining brightness temperatures of various parts of the IR spectrum from space. Thus, IR travelling through the atmospheric window has a brightness temperature of 288K, that in the water vapour absorbing bands of 275K and that passing through the CO2 band of 215K.

    My question is this. As we continue to pump more CO2 into the atmosphere, the climate remains in disequilibrium with more incoming than outgoing energy. It seems to me that, in theory, this could be demonstrated by plotting a falling brightness temperature for IR in the CO2 absorbing band against increasing atmospheric CO2 concentration. Have these measures been made? If not, why not? Is it becauswe we haven’t had access to the appropriate equipment for long enough to show a trend?

    I would appreciate help with the above but, while you are at it, perhaps someone could also explain the logical difficulties I have with my understanding of brightness temperatures and their relationship with altitude. My (possibly dodgy) logic tells me that a lower brightness temperature would indicate less effluent energy per se rather than emission height. (I accept that there will be less radiation at the colder temperatures of the higher atmosphere so I may be quibbling over terminology).

    Finally, I am uncertain why climatologists are so confident that water vapour is a positive feedback. (If it is, I assume that the brightness temperature of IR in the water vapour absorbing bands should also be dropping). I accept that extra surface warmth will increase atmospheric water vapour but will also increase convection which will carry more energy high into the atmosphere above the water vapour level. Water vapour will also presumably translate into more cloud. This, in turn, could increase albedo and absorb some solar energy before it got to the surface. As clouds act as black body radiators in the IR range, clouds could make it more likely that IR would escape to space than to reach the surface. It seems to me (in my ignorance), therefore, that it is quite complicated to decide whether water vapour will be a positive or negative feedback.

    Comment by Douglas Wise — 9 Oct 2007 @ 8:24 AM

  92. Re #91


    I am not sure how they measure radiation temperatures in practice but in principle if the gas has two or more emission bands you compare their relativ intensities. As gases get hotter they tend to emit more in all bands but the increase is greater at shorter wavelengths. Comparing two or more wavelengths, and after a fair amount of calibrating and you can give a value to the effective radiation temperature of the gas.

    If you are inside the gas and the radiation is in thermal equilibrium with the gas then this is the gas temperature. If you are outside the gas it can be more an indicative than an absolute value.

    Perhaps someone who knows how it is done in practice will come along and correct me.

    The absolute brightness is not the important part it is the ratios between different wavelengths. Much like a furnace changes colour when you look through a spy hole. It is the colour not the intensity that indicates the temperature. I have done this and it works.

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 9 Oct 2007 @ 8:56 AM

  93. Rod B., You are indeed close. Basically, all the IR from the surface in the H2O and CO2 bands gets absorbed. Most of the energy goes into collisions with other atmospheric molecules (mostly not ghgs). Some small fraction is emitted from excited ghgs (excited either by collision or by IR). Some goes up, some down. Repeat ad infinitum or ad nauseum, whichever comes first. Eventually, you reach a level where the amount of a particular ghg is small enough that the chances a photon is absorbed are small. Water vapor peters out. Then much higher, CO2 peters out. The ghgs at this level radiate at their effective temperature in the relevant IR line, and that ~5% is what you see from space. I’m sure Gavin, Ray, et al. are wincing at my oversimplification, but in the limit of the spherical horse, that’s how I understand it.

    Comment by Ray Ladbury — 9 Oct 2007 @ 9:24 AM

  94. John Galt (#78) wrote:

    Some skeptics point out that man-made emissions account for only a small percentage of total CO2 emissions into the atmosphere; the rest being from natural sources. I’m finding this hard to reconcile with the large CO2 jump following 1975. Are they saying that only 3-7% of the 380ppm C02 concentration in 2007 is man-made? Which would mean that a large natural CO2 increase occurred following 1975. Am I missing something here? Someone explain this to me. What is meant in these statements?


    Skeptics point out a lot of things.

    They’ve pointed out that CO2 actually has no effect upon the climate system, that what is actually changing the climate system is some sort of delayed reaction to the rise in solar temperatures from the earlier part of this century, that can’t be explained except by mysterious heat retention in the ocean but which we’ve picked up somehow in the rise of rivers. They’ve pointed out that greenhouse gases don’t work because the hot air rises up before it gets a chance to radiate, that there is no such thing as average temperature, that the average temperature hasn’t been rising, that its really magnetic fields thats causing the temperature to rise and even that carbon dioxide can’t be in the upper troposphere or the stratosphere because its heavier than air and when it comes as exhaust, it goes sideways then falls immediately to the ground.

    As I have said, they point out a lot of things, and its usually horse-hockey. And by the way: I didn’t make any of the above up. Its all stuff that’s been published – although the last was in a letter to the editor – by someone who claimed to be a high school science teacher. And all of this is something I’ve run into this year.

    But it might help to know their source.

    However, from what I have seen of the accounting, we pretty-well know its us thats put it up there. Pretty much all of it, down to within a few percent. Although nature has been kind so far in sweeping the majority of it under the rug – or to be more precise – into the oceans and even trees. But the oceans might not be such a good idea. And it has a higher content of a lighter isotope of carbon in just the right percentage to show that it came from fossil fuels.


    Just out of curiosity: who are you?

    Comment by Timothy Chase — 9 Oct 2007 @ 10:01 AM

  95. Ray (David Archer, Gavin …) — one question I keep coming back to.

    We see weather satellite photographs in many different infrared wavelengths. Some show land/water/low clouds; some show water vapor. Other similar imagery shows concentrations of CO2 at different locations and heights in the atmosphere.

    Those images are made with the photons that do move directly from source to satellite — right?

    And photographs in the infrared of the limb of the Earth, like photographs in visible light, are showing the scattered light and infrared from the gases of the atmosphere. Right?

    Comment by Hank Roberts — 9 Oct 2007 @ 10:21 AM

  96. John Galt,
    By all means, natural sources of CO2 emission dwarf those of humans. They always have and will continue to do so. However, until somebody figures out a way to tell those pesky plants, animals, etc. to quit decaying, the only source we can control is anthropogenic. What is more, the ~5% emitted by humans is actually a huge amount, and the fact that human emissions have increased exponentially (compared to stasis in natural sources) is very worrying. I actually find it hard to believe that the folks who propagate such statements are unaware of how misleading they are, but I would be willing to allow them to cop to whatever they think is the lesser charge: mendacity or willful ignorance.

    Comment by Ray Ladbury — 9 Oct 2007 @ 10:28 AM

  97. Alexander Harvey (#89) wrote:

    In that absorption does not necessary equal emission. It depends on the temperature. For instance in the H20 bands there is a net flux in the direction of decreasing temperature. Eventually this turns into a net outboud flux at the TOA.

    You can get a feel for this from MODTRAN if you select low altitudes and select “looking up.”

    In the “looking up” mode it gives you the “Path Length Radiance” e.g the component that comes from the atmosphere not directly from the surface.

    I am aware of the fact that it becomes easier for the radiation to escape as the peaks become narrower due to diminished temperature, and likewise, diminished air density makes the paths longer with upwelling radiation. But I don’t see this as a violation of Kirchoff’s Law: that absorptivity and emissivity are equal under Local Thermodynamic Equilibrium – as Kirchoff’s Law describes the local behavior.

    Alexander Harvey (#89) wrote:

    At low altitudes e.g. .01km the band (wavenumber 100-400) “shines” with a temperature of ~288K i.e. surface air temperature.

    At 1 km it shines with a temperature of ~280K.

    At 4 km at around ~260K.

    The actual temperatures that MODTRAN assigns to 1km and 4km are higher 281.7K and 262.2K.

    If you do the same “looking up” you get very similar radiation temperatures. The band is close to thermal equilibrium which is I think what you were describing. But as there is a temperature gradient so there is a net flow upwards.

    As I understand it, brightness temperature deals with how much radiation is being emitted at a particular wavelength. It says nothing about how much is being absorbed, and therefore would not necessitate a violation of Kirchoff’s law under and circumstances, high pressure or low pressure, warm or cold – for any greenhouse gas.

    Alexander Harvey (#89) wrote:

    This could lead to a paradox as at TOA this band radiates with strengths between the yellow and light blue lines ie an equivalent temperature of between 220K and 240K. This is more or less a net outbound flux.

    Top of the Atmosphere. If this is CO2, by 30 km it is already in non-LTE, although the temperatures don’t really begin to diverge significantly until about 50 km.

    Anyway, thank you for the response. At the very least, we seem to pretty much understand things the same way – except with respect to Kirchoff’s Law. But perhaps there is something I am just not seeing and I have misunderstood Kirchoff’s Law. Something which Eli said would seem to suggest so.

    Take care.

    Comment by Timothy Chase — 9 Oct 2007 @ 10:55 AM

  98. Hank,
    This is a SWAG, but I think that in order to provide images, they have to be direct from the source to the detector. Now, I’m trying to think how I’d image at different levels. One way would be to take advantage of line broadening and image in the tails of the line. You could do this either using a band-gap engineered detector, or more likely by subtracting two filtered images. I’d be really interested to know whether my guess is close.

    Comment by Ray Ladbury — 9 Oct 2007 @ 1:19 PM

  99. In reference to comment #89 Alexander states:
    “I do not know the sensitivity of outbound radiation to temperatures in the upper troposphere but based on MODTRAN my best guess is that a temperature rise of 1C might contribute 0.75 W/m2.
    On the other hand increasing greenhouse gases will I think mean that more energy would need to be supplied to the upper atmosphere to power the thermal radiation output there. These are areas that I know little about but would be interested to know more.”

    If I understand correctly what process Alexander is interested in The following is from “Global Warming The Complete Briefing ” third edition by John Houghton – U of Cambridge Press, 2004

    He describes the process in the upper atmosphere as follows:”Let us imagine, for instance, that the amount of carbon dioxide in the atmosphere suddenly doubled everything else remaining the same(figure 2.8).What would happen to the numbers in the radiation budget presented earlier? The solar radiation would not be affected.The greater amount of carbon dioxide in the atmosphere means that the thermal radiation emitted from it will originate on average from a higher and colder level than before. The thermal radiation budget will therefore be reduced,the amount of reduction being about 4 watts per square metre( a more precise value is 3.7).

    ” This causes a net imbalance in the overall budget of 4 watts per square metre.More is coming in than going out. To restore the balance the surface will warm up.If nothing changes apart from the temperature -in other words, the clouds, the water vapour, the ice and snow cover and so on are the same as before – the temperature turns out to be about 1.2 C.”

    The figure referred to shows 240 W/M^2 incoming (net solar radiation) and 240 leaving. When the carbon dioxide is suddenly doubled the amount leaving is reduced by 4 watts per square meter to 236. Balance is restored to 240 and if nothing else changes apart from the temperature of the surface and lower atmosphere, the surface rises by 1.2 C. If feedbacks are accounted for the average temperature of the surface rises by about 2.5C.

    Hopefully, this will add to further clarification of the energy balance process.

    Comment by Lawrence Brown — 9 Oct 2007 @ 3:11 PM

  100. The responses to “John Galt” have been many and excellent, but perhaps I can add a tiny bit of value. There is a low-level and a high-level answer to the “CO2 is mostly of natural origin” objection. Here’s the low-level answer:

    If we add up the human and natural components of the carbon cycle, we find that sources add up to 217.1 gigatons of carbon (GtC) annually, and that sinks add up to 213.8 GtC. The annual difference of 3.3 GtC is what causes the steady increase in atmospheric CO2. Now, human emissions contribute 5.5 GtC annually, and other human activities (cutting trees, etc.) another 1.6 GtC. Of the gross 7.1 GtC caused by humans, 3.2 GtC stays in the atmosphere, and 2 GtC are absorbed by the oceans. That leaves 1.9 GtC unaccounted for. The mechanisms taking up the missing carbon are under study — leading candidates include more rapid absorption than expected into vegetation and soils. Bottom line: it’s not surprising that humans are causing increases in atmospheric CO2, it’s surprising that we are not adding more.
    The fact that the added carbon is overwhelmingly of human origin has been well established by isotopic analysis, among other methods.
    And here’s the high-level answer:
    If you really think that climatologists, upon hearing this, will clap their foreheads and cry out “Of course! We forgot all about natural CO2! How could we have been so foolish?”, then you and I are inhabiting different realities.

    Comment by jre — 9 Oct 2007 @ 5:56 PM

  101. Ray and others, Eli pointed to a new online textbook that goes into detail about how satellite instruments are used to detect sea surface temperatures in the infrared, it’s good info generally about how it’s done. Directly to that section:

    Comment by Hank Roberts — 9 Oct 2007 @ 8:43 PM

  102. Ryan P. (87) re J. Galt

    It would be helpful to include all natural sources and sinks of CO2 for comparison. Barton (88) added some. I thought Timothy would too in (94) but he just couldn’t make it past his diatribe [;-). I wonder (and have asked) the effect of carbonaceous rock as a sink. It also seems that because of the magnitudes involved, a slight anomaly in the natural source/sink process could have an impact. This is a pure speculative question, however. I agree that the argument from my fellow skeptics that ‘man adds just some tiny percent of the total added CO2’ is looking at just a piece of the puzzle, is a blind alley, and misleading.

    Comment by Rod B — 9 Oct 2007 @ 8:50 PM

  103. > asked … carbonaceous rock as a sink …

    Answered — explained by experts in the field

    From the discussion at

    Comment by Hank Roberts — 9 Oct 2007 @ 9:59 PM

  104. Greenhouse gases are warming the planet and will continue to do so. Argue about the rate as much as you wish. This is a recent event only and was not significantly present beyond a century ago. Key point.
    Some other influence(s)directly caused significant changes to global climate over the last 3000 years and longer – without greenhouse gases. Indisputable! Argue about this for as long as you like. It did happen.
    Solar cycles appear to be directly related to the longer term global climate influences – this seems to be perfectly logical. Solar cycle 24 is already late and getting later. Fact.
    It is to be appreciated that more than one influence impacts our climate – not only greenhouse gases.
    The issue is ‘What have been the quantitative measures of the respective influences, and more importantly, what will they be in the future’.
    It seems rather stupid for surposedly scientific commentary to focus on any particular influence or effect to the exclusion of others, rather than to be objective in assessments and presentations.
    Can we please seek some definitive work(s) to provide meaningful information relating to the relevant factors that directly impact upon global warming or cooling.

    Comment by David Norrish — 10 Oct 2007 @ 2:49 AM

  105. Hank, Thanks for the reference on ocean temperature measurement. That fills in some blank spaces. I suppose that in looking at the atmosphere, the signal is the clouds and the ocean forms the background. They are now doing some interesting stuff with bandgap engineered semiconductors. These could be very useful for future instruments, but I’m not sure how closely you can tailor the bandgap.

    Comment by Ray Ladbury — 10 Oct 2007 @ 7:22 AM

  106. Timothy,

    Re: #97

    Kirchoff’s Law is a bit of a nightmare. Well I think so.

    It is also written down by different people in different ways and that does not help.

    For a body in Local Thermodynamic Equilibrium whether in radiative equilibrium or not emissivity = absorptance. For a surface they are material properties, for a gas a function of material properties the volume, density, pressure. etc. The important point is that they are equal when the body is in LTE. For a blackbody they are constant and equal 1, for real materials they are not necessarily constant and are less than or equal to 1.

    If the body is in LTE and radiative equilibrium then emission = absorption.

    I think it is this last statement that reflects Kirchoff’s original idea.

    The atmosphere is in, or close to, LTE and so emissivity = absorptance but not in radiative equilibrium so emission does not necessary equal absorption.

    If the radiation background is “hotter” than the body absorption will be greater than emission, the body will warm in an attempt to attain radiative equilibrium. In the troposphere the major governing factor is probably the lapse rate not radiative equilibrium and so although LTE exists radiative equilibrium does not.

    I hope this helps, to be honest whenever I feel I understand Kirchoff I find it best to lay down in a dark room until I am feeling better.

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 10 Oct 2007 @ 11:34 AM

  107. Alexander (Re: 106) Actually one of the clearest expositions I’ve read is in Landau and Lifshitz Stat Mech book. They state that the blackbody distribution is purely a product of the equilibration of the radiation field. However, photons do not interact with each other, so the only way for the field to come to equilibrium is via interactions with surrounding matter. So, the emissivity is entirely a property of the matter. In fact, emissivity does change with pressure, temperature, etc. in solids–just much more slowly. Here too, there is a continuum. The hydrogen atom has single lines. Bring in 2 electrons with helium, and the lines get split by spin-orbit effects lifting the degeneracy. Now put the atom in a molecule and the lines are further distorted and broadened. The molecule goes into a gas or liquid and you have pressure broadening, etc. In a solid, the atom-atom interactions are strong enough that energy lines become bands, which are themselves affected by pressure, strain stress, etc. Yesterday’s Nobel prize is an example of how tailoring the interactions of electrons can produce interesting and surprising properties.

    Comment by Ray Ladbury — 10 Oct 2007 @ 12:49 PM

  108. David Norrish (#104)

    A good place to start for an overview of the science involved in the picture of the current warming is the IPCCs fourth report (IPCC AR4, see the link at the top right of this page under “Science Links”).

    The Working Group I “Summary for Policy Makers” has a nice chart (“Radiative Forcing Components”) for what they consider to be the relative influence on our recent climate changes. They include solar influence.

    If you want to know how they arrived at their decisions, which papers they consider authoritative and why they did not consider others at this time; download WGI chapter 2 “Changes in Atmospheric Constituents and in Radiative Forcing”. It includes their discussion concerning solar influences in section 2.7.1.

    Comment by Dan W — 10 Oct 2007 @ 1:31 PM

  109. Ray, I’m confused (I think). I thought the “line spectra” of, say, hydrogen, was caused by jumps in the electronic energy levels (with emission and/or absorption) and not directly related to Planck blackbody-type radiation. Or did I totally misread your 107??

    Comment by Rod B — 10 Oct 2007 @ 9:18 PM

  110. Ray, on how they measure CO2 levels in the atmosphere from satellites,
    I think it’s by selecting particular wavelengths (and comparing the satellite work to existing data).

    For now all I can do is point to abstracts and hope one of the experts will come along.
    (after the middle of next year sometime, the AGU back issues will be searchable online).

    Here’s another hint:

    “Although originally designed to measure atmospheric water vapor and temperature profiles for weather forecasting, data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua spacecraft are now also being used by scientists to observe atmospheric carbon dioxide. … using several methods to measure the concentration of carbon dioxide in the mid-troposphere (about eight kilometers, or five miles, above the Earth’s surface).

    “This global map of mid-troposphere carbon dioxide shows that despite the high degree of mixing that occurs with carbon dioxide, the regional patterns of atmospheric sources and sinks are still apparent in mid-troposphere carbon dioxide concentrations.”

    Comment by Hank Roberts — 11 Oct 2007 @ 12:14 AM

  111. RodB, try reading these pages:

    Key Points:

    * Anything that absorbs also emits.
    * A cloud of cool gas that absorbs certain colors from a blackbody will emit exactly those colors as the gas atoms de-excite
    * If we look at the cloud without the blackbody in our line of sight, we will see an emission line spectrum.
    * The lines of emission have the same color as the absorption lines in the absorption line spectrum
    * If you added an emission line spectrum and an absorption line spectrum, you would get a continuous spectrum.

    Comment by Hank Roberts — 11 Oct 2007 @ 7:32 AM

  112. Rod B., electromagnetic radiation can come from atoms only where they can radiate–that is from transitions between energy states. Thus, a hydrogen atom at room temperature is going to be pretty inert. A hydrogen molecule, also will not do much radiation, although hydrogen in a gas can break the symmetry of the typical diatomic molecule and you might get some radiation due to rotational transitions. If you have a copy of Landau and Lifshitz, the exposition is pretty clear: the Planck distribution is a property of the photon gas in equilibrium, and it is a continuous distribution. However, the only way for it to achieve equilibrium since photons don’t interact with each other.
    I think that you are still thinking that atoms have two mechanisms for emitting energy–“thermal” and “quantum”. To see why this is not true, consider the types of energy an atom or molecule can have: 1)kinetic–which is continuum, 2)electronic–quantized, 3)vibrational–quantized, 4)rotational (for molecules w/ more than 2 atoms or distorted diatomic molecules)–quantized. Exchanges of kinetic energy can occur continuously via collisions, but these do not involve emission of radiation. You can also excite a vibrational, rotational or electrical mode via a collision, but this energy will be quantized. All other energy transitions are quantized–from one quantized energy to another.
    The Planck spectrum occurs because matter (solids, molecules, atoms, ions, etc.) absorb and radiate energy in their energy lines and bands. Collisions excite these same energy transitions, but the numbers of collisions that can do so varies with temperature. Thus, at room temperature, almost no collisions excite electronic transitions, but they can excite vibrational transitions. On the sun, most of the transitions are electronic and most of the photons are in the visible. Does this help.

    Comment by Ray Ladbury — 11 Oct 2007 @ 7:39 AM

  113. Rod B. and Hank,
    This is cursory, but the concept of emissivity is important for understanding how blackbody radiation relates to thermal radiation of real gasses/atoms.

    Comment by Ray Ladbury — 11 Oct 2007 @ 9:18 AM

  114. Thank you Ray and Timothy and all

    Your replies helped and did not help, the questions keep poping up.
    I thought clouds could form at 5-6 km up, close to where IR could escape to space so that increased evaporation would give some negative feedback to temperature, but this appear not to be very significant. I know the reduction of IR would be small compared to the total IR.
    An example that didn’t help:
    Timothy’s “this is only because the time between collisions for any given molecule tends to be much shorter than the half-life of an excited state”, then another question appears; Ok, but isn’t this then just a transfer of IR energy from the ghg absoption bands to heat the rest of the spectrum?
    But never mind, knowing I’m wasting time of some brilliant minds in here, can somebody point to another web site more for amateurs and ignorants? RC is probably more by and for experts and “true believers”.

    Comment by lgl — 11 Oct 2007 @ 11:45 AM

  115. Igl (114) — Scroll down the sidebar to the Other Opinions section to discover which site best meets your needs.

    Comment by David B. Benson — 11 Oct 2007 @ 12:05 PM

  116. Ray, I think you’re right in saying to Rod:
    “I think that you are still thinking that atoms have two mechanisms for emitting energy–”thermal” and “quantum”

    Can you try for a fifth-grade level explanation (poetry, not math)?

    I think the answer is — if we take a huge mass of hydrogen (enough to hold together by its own gravity) then its molecules are all constantly interfering with each other, so energy is being transferred among all possible forms.

    Think of a ‘chaotic pendulum’ — several off-center masses each attached. Push any of them and the whole connected thing starts to move, but which piece moves which way and how fast? It varies constantly. Imagine shooting BBs at one of those — you’d get ricochets of all energies, some dead slow and some very fast.

    I’m not sure that helps. But the point is that all radiation, all photons, are described by quantum mechanics. A hot dense mass (what we think of as normal solids, and hotter things) gives a broad average curve peaking at the ‘temperature’ which is also an average.

    Comment by Hank Roberts — 11 Oct 2007 @ 12:05 PM

  117. Hank, that’s a reasonable analogy. Physically what is going on is this. In an isolated single-electron atom, the electron exists only at certain energies because energy determines wavelength and the electron waves have to interfere constructively. Now add another electron–you get more interactions, more energies…
    In a molecule, you now have vibrational and perhaps rotational modes. Put the molecule in a gas, and now the energy levels get further broadened. In a solid, energy lines interact with eachother and broadened still further until they meld into energy bands–so there’s a limited continuum–any energy in one band to any energy in another–of radiation. The point is that the more density increases, the more matter you get, the closer you get to a continuum–to a quasi-classical–result.

    BTW, LGL–we’re all learners here. Keep asking questions.

    Comment by Ray Ladbury — 11 Oct 2007 @ 2:10 PM

  118. lgl (#114) wrote:

    Thank you Ray and Timothy and all

    Your replies helped and did not help, the questions keep popping up.

    Well, let’s see what we can do with the questions you have left. Believe it or not, this often helps me to understand things a little better as well.

    lgl (#114) wrote:

    I thought clouds could form at 5-6 km up, close to where IR could escape to space so that increased evaporation would give some negative feedback to temperature, but this appear not to be very significant. I know the reduction of IR would be small compared to the total IR.

    The main negative feedback which comes from clouds is increased albedo where they scatter visible light back into space before it has a chance to reach the surface and get converted into infrared. Clouds will form at a variety of altitudes, although I would expect the bulk to be below the effective radiating layer of 6 km, with or without the enhanced greenhouse effect. However, clouds are also pretty close to being black bodies in the infrared spectrum, and when they absorb thermal radiation at lower altitudes, they actually tend to raise the ground temperature – then the temperature of the atmosphere.


    At a more technical level, given the fact that in a local thermodynamic equilibrium, good absorbers at a given wavelength are equally good radiators (Kirchoff’s Law), the net direct effect of absorption and radiation would be neither to locally warm or cool the atmosphere But the atmosphere is also gaining thermal energy from moist air convection as well as thermal updrafts. This thermal energy stands an equally good chance of being radiated along with the energy coming from absorption. Likewise, there is the thinning of the atmosphere with altitude, resulting in longer paths between radiation and absorption. As such there tends to be an excess of radiation over absorption.


    lgl (#114) wrote:

    An example that didn’t help:

    Timothy’s “this is only because the time between collisions for any given molecule tends to be much shorter than the half-life of an excited state,” then another question appears; Ok, but isn’t this then just a transfer of IR energy from the ghg absoption bands to heat the rest of the spectrum?


    The question keeps popping up when the bit about the time between collisions being shorter than the half-life gets mentioned. I know this is something I had to think about. But I worry sometimes about repeating the more detailed answers – as the people who have been here longer than myself might get tired of reading my posts.

    However, the key to the answer is already in the question itself.


    GHG molecules don’t know how long they have been in an excited state, and as long as a certain percentage are in an excited, some of them will spontaneously decay. Essentially the coins of spontaneous decay keep getting passed around, and they keep getting flipped. Doesn’t matter which ghg has them at any given moment.

    So yes, even when a GHG molecule becomes excited, either as the result of absorption or as the result of a collision, overwhelmingly the chances are that it will lose this energy by means of collisions before it has a chance to decay – but this is irrelevant as long as a certain percentage of ghg molecules are excited at any given time. Spontaneous decay will happen to some of them.


    At a more technical level…

    … for another Chris Cringle or two, it is also true that the vast majority of the thermal energy within the atmosphere (roughly 98%, I believe) is possed by molecules that in very large part are incapable of spontaneous emission. Nitrogen and oxygen are examples of this. Given the fact that they consist of only two atoms of the same element, they are incapable of entering the quantized states that GHG molecules are (e.g., vibrational, rotational, and vibrorotational, where pure rotational is possible only with permanently dipolar molecules, e.g., water but not carbon dioxide) and as such largely do not participate in thermal emission except by way of transfering their energy to greenhouse gases through thermal collisions.

    However, locally all of the gases will be at the same temperature. The bulk of the atmosphere will be in Local Thermodynamic Equilibrium. This will be due to the air pressure being typically at 20 mb or above (where the surface air pressure being at 1013 mb), which means that the molecules are experiencing a million collisions or more within the half-life of the excited states which result in thermal emission. Given the high rate of collision, at the populational level the modes of excitation will share equally in the thermal energy, being at the same temperature as that of the atmosphere itself.

    At altitudes where the air pressure is low enough that the atmosphere is no longer in local thermodynamic equilibrium, the temperatures of the various modalities begins to diverge. The biggest one to diverge first is the 15 μm of carbon dioxide at about 30 km, a strongly self-absorbing band of lines which will then (I believe) tend to diverge towards higher temperatures than the surrounding atmosphere.


    lgl (#114) wrote:

    But never mind, knowing I’m wasting time of some brilliant minds in here, can somebody point to another web site more for amateurs and ignorants? RC is probably more by and for experts and “true believers”.

    With me its more tenacity than intelligence. And Real Climate is for anyone who wants to learn.

    If you have questions at whatever level, you throw them out. If someone thinks they have an answer hopefully they will respond. But take whatever is said by the amateurs such as myself with a much larger grain of salt than the climatologists. We are in the same boat – just different seats.


    Incidentally, here one thing to always keep in mind….

    If given one argument or another greenhouse gases were able only to absorb but never radiate, energy would in very large part never be able to get out of the atmosphere – except I suppose with what little kinetic energy got transferred back to the surface. Neither convection nor can’t get thermal energy out of the atmosphere. But the atmosphere doesn’t keep heating up, and the good bulk of it is at a lower temperature than the surface.

    So how is the thermal energy getting out of the atmosphere? The only way that it can get out of the climate system. It is either being radiated into space directly from the atmosphere or indirectly by being radiated back to the ground one or more times before finally being radiated back out into space.


    But have we actually observed greenhouse gases emitting thermal radiation?

    Definitely – by way of satellite and at various altitudes. Each line begins to escape into space as the atmosphere begins to go from being opaque to it to being transparent to it.

    For a good number of examples to this including motion video, please see the links in my earlier comment #555 to Part II: What Angstrom didn’t know.

    But have we actually directly observed the greenhouse effect?

    Yep, at least in the case of water vapor.

    Please see:

    Valero, F. P. J., W. D. Collins, P. Pilewskie, A. Bucholtz and P. J. Flatau (1997),
    Direct Radiometric Observations of the Water Vapor Greenhouse Effect Over the Equatorial Pacific Ocean,
    Science, 275, 1773–1776.


    Anyway, I hope this helps – and gives everyone more to peak their curiosity.

    Comment by Timothy Chase — 11 Oct 2007 @ 3:06 PM

  119. I cited the article:

    Direct radiometric observations of the water vapor greenhouse effect over the equatorial Pacific Ocean
    F.P.J. Valero, W.D. Collins, P. Pilewskie, A. Bucholtz, and P.J. Flatau
    Science, 274(5307), 1773-1776, 21 March 1997

    … in 118.

    Actually, it turns out that what they were measuring wasn’t simply a greenhouse effect, but a “super” one.

    Here is the abstract:

    Airborne radiometric measurements were used to determine tropospheric profiles of the clear sky greenhouse effect. At sea surface temperatures (SSTs) larger than 300 Kelvin, the clear sky water vapor greenhouse effect was found to increase with SST at a rate of 13 to 15 watts per square meter per Kelvin. Satellite measurements of infrared radiances and SSTs indicate that almost 52 percent of the tropical oceans between 20 N and 20 S are affected during all seasons. Current general circulation models suggest that the increase in the clear sky water vapor greenhouse effect with SST may have climatic effects on a planetary scale.

    … and a teaser from the main text:

    Satellite studies (8–10) have found that for clear skies and SSTs above 298 K, the spatial variation of Ga with SST, dGa/d(SST), exceeds the rate of increase of sea surface emission, ds(SST)4/d(SST) = 4σ(SST)3. For a tropical SST of 300 K, 4σ(SST)3 ~ 6.1 W m-2 K-1. This effect, termed the “super greenhouse effect” (11), occurs in both hemispheres during all seasons. It is also observed for interannual variations of Ga with SST during the El Nino in the tropical Pacific (12). Observations in the tropical Atlantic ocean (11) show that the clear sky downwelling infrared flux incident on the surface (Fa) also increases faster than the surface emission with increasing SST. The net result is further warming of the surface, which in turn induces additional heating of the atmosphere column above.

    Comment by Timothy Chase — 11 Oct 2007 @ 5:20 PM

  120. Alexander Harvey (#106) wrote:

    I hope this helps, to be honest whenever I feel I understand Kirchoff I find it best to lay down in a dark room until I am feeling better.

    Here is what Eli stated (comment 180 to The weirdest millennium) at one point:

    Now you are not the first to doubt this happens (there are even papers that snuck into print), but it is still wrong. Re-radiation in keeping with Kirchhoff’s law and our ability to model what happens was demonstrated in Applied Optics 35 1519 (1996) by Evans and Puckrin. (And yes I know about convection, but you just have to account for the additional energy flows)

    The experiment was simple enough and it is elegant (IMHO) in the parsimonious way that it answers a complicated question.

    Evans and Puckrin showed that the radiative transfer codes based on spectroscopy and Kirchhoff’s law could perfectly reproduce the measured emission spectra.

    This means that not only do you SEE the effect of that 0.03% CO2 in the IR emission spectrum, but you can, from first principles, calculate what it looks like.

    On the other side, emission from CO2 has been seen in the atmosphere, again, in good agreement with the radiative codes.

    As Ray Ladbury made clear, sensible physicists had no doubt about Kirchhoff’s law applying. The Evans and Puckrin paper did not raise any fuss because it confirmed the obvious, but still one constantly encounters the equivalent of Barretts denialist driven misreading of the science. When you are trying to beat back a pail full of spaghetti that is being thrown against the wall, some will get through and pollute the atmosphere. Witness the silly recent paper by Beck, and much more.

    It looks pretty solid, and it looks like it applies at the level of the individual wavelengths. Below 20 mb you are into non-LTE conditions where Kirchoff’s law no longer applies. However, the first big deviation begins to creep in with CO2’s 15 μm at about 30 km. Up until you get to that altitude the brightness temperature of the line is the same as that of the atmosphere itself, and all of the brightness temperatures for the different modes of CO2 excitation are the same as that of the atmosphere itself.

    Anyway, we can both dig into this some more – I will be looking for the paper by Evans and Puckrin. But I don’t think I will be laying down Kirchoff’s law as of yet.

    Comment by Timothy Chase — 11 Oct 2007 @ 9:09 PM

  121. If you liked my June Lavoisier paper, then you will love my next one. The message remains the same – increased atmospheric CO2 is wholly beneficial.

    Comment by David Archibald — 12 Oct 2007 @ 12:21 AM

  122. [[If you liked my June Lavoisier paper, then you will love my next one. The message remains the same – increased atmospheric CO2 is wholly beneficial.]]

    Getting smashed in the head with a brick is wholly beneficial, too. I wish more global warming alarmists would realize that.

    Comment by Barton Paul Levenson — 12 Oct 2007 @ 6:08 AM

  123. David Archibald, You make a blanket statement that increased atmospheric CO2 is wholly beneficial. The uncritical universality of your statement by itself establishes it to be fiction. Even if we were to grant some benefits, surely these benefits would not be uniform. Pacific Islanders are already coping with rising sea levels. Hunts of Eskimos are already failing due to dwindling sea ice. I suspect there will be winners who benefit from climate change. All the evidence points to there being far more losers than winners, though. But then, you clearly have never been about evidence, have you?

    Comment by Ray Ladbury — 12 Oct 2007 @ 7:50 AM

  124. No adverse side effects are expected, eh?

    Same claim you made in 2005 for the pills you were offering to men with prostate cancer.

    How’s that going? Published results yet?

    Comment by Hank Roberts — 12 Oct 2007 @ 9:12 AM

  125. Hank, Ray, et al: I have to dig further into your-all’s posts to maybe find what I’m missing. But one simple roadblock keeps getting in the way. If blackbody/Planck-function radiation all stems from the quantum energy levels (electronic, rotational, vibrational) in an atom or molecule, how can the continuous spectrum be explained? The Sun as an example. First, whatever rotational and vibrational molecular levels might exist in the Sun, they predominately fall in the infrared or microwave range which we see little of in solar radiation. Second, then, the overwhelming amount of visible spectrum radiation would have to come from hydrogen electronic transitions. I’m assuming there are a dozen or two possible levels. Even with all of the potential “line spreading”, I can’t fathom those dozen lines spreading out for the full continuous very smooth spectrum from infrared to UV. Is that what you contend? Why does the formula for emittance cover every wavelength and have only temp as the independent variable — no molecular quantum energy levels or nothing? How does it work with the cosmic background? How does it work with solids, say a carbon cube or a rock painted flat black?

    I didn’t fully get the Wikipedia reference. It looked like it was confusing transmission with emission, for one…

    I appreciate your-all’s indulgence and help.

    Comment by Rod B — 12 Oct 2007 @ 12:50 PM

  126. Rod, do you know an answer to “how does a photon get produced in the first place, and what happens when a photon is absorbed?”

    That’s addressed in some of those prerequisite courses — the ones people need to pass before taking the radiation physics course.

    I haven’t. That’s why I keep saying this is at best poetry, trying to find words that give some sense of what the math describes.

    A photon started out as a bookkeeping entry. Einstein got his Nobel for work on the photoelectric effect.

    Here’s a teaching example. See if this helps:

    The method described worked for his class, who weren’t at all well prepared for even basic physics:

    “In a subsequent class period, I distributed a collection of short passeges from all the student models for class discussion so they could see that they were describing the same phenomenon in somewhat different ways. I also included, as if it were taken from one of the student models, an excerpt3 from a translation of Einstein’s original paper on the photoelectric effect.4,5 Later I revealed to the students that the excerpt was from Einstein and that this was the paper that won him the Nobel Prize. This led to a discussion of how it was possible for them to arrive in two hours at a model that eluded the best scientists of the late 19th century for years.”

    Comment by Hank Roberts — 12 Oct 2007 @ 1:07 PM

  127. Rod, you’ve understood that when a molecule, or the atoms in a molecule, move in space, a quantum of energy (called a photon) can be kicked out and go traveling.

    If the atom or molecule is floating all by itself, not interacting, then it can only move in a few particular ways limited by its own structure.

    It has only its own individual energy, in discrete chunks.

    A whole lot of atoms and molecules close together are interacting, and the banging and pulling and tugging and twisting among them increases the possible motions that parts of that mass of stuff can do in space. And with the mass of stuff all interacting, you can state an ‘average’ amount of energy there — that’s temperature.

    And once the stuff that’s interacting so is doing it enthusiastically enough it has an ‘average temperature’ and the motions of the masses involved are so _huge_ compared to the little tiny motions of an individual molecule that the photons produced are overwhelmingly those from the big movements, the ‘temperature’ — and as the mass gets hotter the average temperature rises and we get infrared (huge amounts, perceptible heat, not just a band in a spectroscope) and then red – yellow – blue – ultraviolet as the mass gets hotter and hotter.

    The little individual photons from the little individual motions of the molecules are still in there, but those molecules aren’t floating cold and alone, they’re also doing the mosh pit slam dance avalanche movements, and those create far more photons of all possible sorts.

    Caveat: it’s doggerel, maybe poetry, just an attempt to find words. Let’s see if one of the radiation physicists can get the coffee out of his or her keyboard and say something more useful about this.

    ““how does a photon get produced in the first place, and what happens when a photon is absorbed?” is something like:

    When a mass moves, the mass moving in space can make energy transfer through space.

    Comment by Hank Roberts — 13 Oct 2007 @ 10:11 AM

  128. Hank, I pretty much know what happens when a photon is absorbed, but have never fully grasped why a photon/light wave gets emitted when internal energy levels change… other than it makes sense to mirror the absorption. But then if you get far enough into the “whys”, physics runs out of answers!

    Comment by Rod B — 13 Oct 2007 @ 11:25 AM

  129. Rod B., My previous several posts have touched on this. In a nutshell–the more particles you have interacting, and the more intense the interactions, the more the energy “lines” get distorted. Thus when you look at light escaping from a cavity, it has not only interacted with the material in the walls of the cavity, but with the gas in the cavity, etc. So when you look at this light, you don’t see the spectra characteristic of the wall material or the gas, but a pretty near blackbody spectrum.
    As to your question of why you get a photon from a transition–it is because you can only have electronic/rotational/vibrational states at certain energies. If you got a molecule that tried to go to a forbidden energy, its wave function would destructively interfere with itself (in other words, it’s impossible). As to why you get spontaneous transitions from high to low energy in the first place, you can look at it 2 ways: 1)the low-energy state is more favorable 2)since the spontaneous high-to-low transition is energeticallly possible, it MUST happen (while of course the low-to-high transition cannot happen spontaneously). Now lot’s look at the Sun–it’s not just a ball of neutral hydroge, but rather a plasma–free protons and electrons along with and interacting weakly with other ions and neutral atoms. This is what removes the largely line character of the spectrum. Does this help?

    Comment by Ray Ladbury — 13 Oct 2007 @ 4:47 PM

  130. “Why” is a question one can keep asking forever, that’s true. “If we do this we observe that” is about as good as it gets in science. That classroom teaching exercise I linked above shows how a class of ordinary students can, given the observations, can reason their way to the same answer Einstein did about what happens.

    Comment by Hank Roberts — 13 Oct 2007 @ 5:18 PM

  131. Hank, at first blush your 127 sounds neat. One picky problem (maybe). That individual molecule’s energy is in discrete chunks all right, but that has practical application only to rotation and vibration energies. The difference between the “chunks” of translation energy (1/2mv2 stuff) is so tiny those “quantums” are virtually indistinguishable, kind of like the quanta of an speeding automobile.

    Comment by Rod B — 13 Oct 2007 @ 7:09 PM

  132. I want to thank everyone for the responses to my question. I’ve only recently started looking into AGW on a serious level. The inter-play between the two poles of the debate (or non-debate as realclimate contends)provides endless comedic value.

    and to Timothy Chase who asks “Who are you?”
    As yet only a pretender.

    Comment by John Galt — 13 Oct 2007 @ 7:11 PM

  133. It gets deep fast:

    “… if we ask how much energy a beam of light of a certain frequency, f, deposits on an absorbing surface during any time interval, we find the answer can only be nhf, where n is some integer. Values such as (n+1/2)hf are not allowed.

    “To get some idea of how counter-intuitive this idea of discrete values is, imagine if someone told you that water could have only integer temperatures as you boiled it. … It would be a pretty strange world you were living in if that were true.

    “The world of quantum mechanics is pretty strange when you try to use words to describe it.”

    So they draw pictures:

    Here, we’ve been talking about photons. They say:

    “…. traveling electromagnetic waves such as light … are electromagnetic waves and differ only in wavelength.

    “In the quantum field theory, any changing electromagnetic fields or electromagnetic waves can be described in terms of photons.”


    “When there are many photons involved, the effects are equally correct (and more simply) given by the earlier non-quantum theory, namely Maxwell’s equations.”

    Back from the brink of quantum theory — at least in the lower atmosphere. I can’t say whether radiation transfer in the upper atmosphere requires quantum theory to describe what’s happening in very thin air.

    I suspect so.

    Comment by Hank Roberts — 13 Oct 2007 @ 11:44 PM

  134. True, Hank, but heating water does increase its temp by discrete steps, with intergers (or 1/2 intergers) part of the mathematics… along with Planck’s constant.

    Comment by Rod B — 14 Oct 2007 @ 11:42 AM

  135. Rod B, We cannot say with certainty whether temperature is quantized, as the steps are too small to measure. For all practical purposes this can be treated classically. Quantum effects tend to manifest 1)for very small scales of mass, distance and time; 2)for systems confined to fewer than 3 dimensions. When a system is unconfined and sufficiently large and longlived, quantum effects are negligible.

    Comment by Ray Ladbury — 14 Oct 2007 @ 1:30 PM

  136. Rod, c’mon.

    Comment by Hank Roberts — 14 Oct 2007 @ 7:59 PM

  137. Ray, I just can’t get it through my thick skull. The characteristic radiation as seen with a spectroscope shows extremely sharp and narrow lines (or voids), some wider than others, granted, but still very narrow compared to the visible-plus spectrum. This is true for the Sun and stars. The characteristic lines certainly do not go away and get lost in the mashing together of all the photons to make a complete blackbody spectrum. So we’ll have to leave this hanging out there.

    I liked your explanation of why photons are generated with changing energy levels. Thanks.

    re 135. I agree. It is impractical to think much about quantum steps in macro/classic physics stuff. Like it makes little sense to consider Uncertainty while parallel parking. [;-) But, none-the-less, ALL energy is quantized

    Comment by Rod B — 14 Oct 2007 @ 8:39 PM


    Comment by Hank Roberts — 15 Oct 2007 @ 5:00 AM

  139. Rod B., WRT the Sun, you have both a hydrogen plasma, but also neutral hydrogen–so you have a hydrogen absorption spectrum superimposed on a blackbody curve. You see similar features in the IR with Earth. There is no reason why a body as large as the Sun cannot exhibit both continuum and quantum features in its spectrum.

    Comment by Ray Ladbury — 15 Oct 2007 @ 7:49 AM

  140. Even the Devil can quote scripture for his purpose – The Merchant of Venice. Thankyou for putting the MODTRAN facility together. We would be in the dark on the true extent of the log effect otherwise. And you are right, after that comes the climate sensitivity. What I like about Idso’s number is that it is derived from observations of nature, not models, which, no matter how diligently they are assembled and attended to, might leave something out, and thus be wrong, and lead us astray. Anyone who doesn’t like Idso’s sensitivity figure might care to read his paper, and determine where he went wrong. I don’t think you can, so his number stands. If you are true seekers of wisdom, this you will do.

    [Response: I wonder if you notice the irony in your quote? The “true extent” of the log nature of CO2 forcing is well known and discussed in every IPCC report and included in every climate model – how is that keeping it in the dark? And as for climate sensitivity, Idso’s estimates suffer from all the same problems as those discussed here – you can’t just divide a temperature by a energy flux to get the global climate sensitivity. You need to do it on a global basis as discussed here – and those estimates (all drawn from observations) give numbers near 3ºC for 2xCO2. -gavin]

    Comment by David Archibald — 15 Oct 2007 @ 8:28 AM

  141. So, Rod, point to what you’re thinking you remember about bright line emissions in sunlight please?

    You I think are remembering that spectral lines are _detectable_ (like helium, first discovered as a spectral line in the sun) and assuming that means they’re strong lines.

    Not so. There are lines, but they’re the dark ones for absorbtion.

    That’s clearly explained above.

    If you’re getting an explanation from some other source please post your source. If you’re making your mind up based on logic rather than relying on someone’s statements, you aren’t stating a basis for your thinking that you can point to.

    It’s only in a cold thin gas where the individual spectral lines stand out. Like space or, I think, the top of the atmosphere.

    A hot plasma like the sun, or a planet’s surface like Earth, aren’t diffuse thin gas and emit so much else that the individual clear lines are barely detectable.

    Online references for standard spectra at top of atmosphere, and reference to nonstandard tools including MODTRAN (the atmosphere is a constantly changing filter):

    Remember the discussion many topics ago about where the initial math for radiation transfer came from — work on solar atmospheres. There’s coursework, you can probably get the textbooks and do it if you want a real understanding. This is just throwing words at the subject here, you know.

    Results — about 89,200 English pages for radiation transfer gas physics math. No “Wisdom” button available.

    Graduate Courses in Astronomy – University of Michigan
    The radiative transfer of the light in matter is developed and a subset of the … Introductory sections on particle, fluid dynamics and plasma physics are …

    Physical processes in low density gases including radiation transfer, … and the interaction between gas and dust. P: Math 222 and Physics 205 or 241. …

    Comment by Hank Roberts — 15 Oct 2007 @ 8:49 AM

  142. David Archibald, The idea that an observation or even a set of observations is less likely to lead us astray than a model is pretty weird. I mean, after all, the model presumably is traceable to observations. Moreover, the observations you base your number on could just as easily neglect a factor that is unimportant on their timescale but very important on longer timescales. Models are based on observation, but suplemented with physical understanding (also with its roots in observation). This is the reason why science is more (and more effective) than a simple detailed logbook. If you don’t understand this, then you don’t understand science.

    Comment by Ray Ladbury — 15 Oct 2007 @ 10:13 AM

  143. Ray (139) and Hank (138, 141), I fully agree with this. I was simply saying the sources of the continuous radiation and the discrete/quantum radiation are not the same. Specifically, the continuous “blackbody” radiation does not come from the “spreading” the molecular quanta radiation, as Hanks’s reference in 138 states. (Thanks.) You can have both (one way or another).

    Nor do I disagree (nor did I say otherwise) that spectrography looks at discrete lines and/or discrete voids (blanks, black lines, whatever) depending on the situation. You get blank lines when the energy non-equilibrium causes the molecules/atoms to only absorb radiation from the continuous spectrum source into their internal quantum energy levels, gaining energy in the process, but not emit that energy (losing energy in that process) at its discrete wavelength(s) (to 4-7 decimal places in the nm range, BTW — before spreading).

    Comment by Rod B — 15 Oct 2007 @ 12:01 PM

  144. Sorry guys but all the model you need is this:
    El Nino add 0.2 oC, La Nina subtract 0.2 oC, and correct some for large volcano eruptions.
    GISS data for low latitudes:
    clearly show the stepy nature of the temperature rise.
    During periodes with more La Nina events than El Nino events, the temperature drops,
    where they are in balance there is almost no change, and when El Ninos are in majority the temperature rise:
    From 1976 to 1983 there are two more El Ninos so temp anomaly goes from roughly -0.1 to 0.3, Then the next 15 years there are an even number of El Ninos and La Ninas so temp only increases some 0.05 oC per decade! Then the El Nino in 2002, without a following La Nina, brings it to 0.5 oC. The El Nino in 2006 was not very powerful so the present La Nina shold bring it down to around 0.3, and hey, we are almost there!


    Comment by lgl — 15 Oct 2007 @ 12:50 PM

  145. Rod, look at what happens to the transitions of the hydrogen atom as you go to higher excited states. The energy levels get closer and closer until they are essentially a continuum. It’s not as if there is a definitive line that divides “continuum” and “quantum”.
    The blackbody spectrum is the product of the photon gas coming to equilibrium with itself–but it does so by interacting through the matter around it. The more complicated the species in the matter and their interactions, the closer you get to a continuum.

    Comment by Ray Ladbury — 15 Oct 2007 @ 1:03 PM

  146. Rod, the sources are “the same” in that the sources are movement of mass in space.

    Isolated molecules move in very few ways and produce very specific emissions.

    Crowded molecules in solids or dense gases move in all possible ways and produce emissions of all possible wavelengths, peaking at the average wavelength for the average movement, the “temperature”

    I don’t have the prerequisite advanced math and physics, and you know this is just words, but do you agree that all energy emitted is due to masses moving in space? And the masses affected by other masses move in less precise increments so we get photons of all kinds of energies out?

    Comment by Hank Roberts — 15 Oct 2007 @ 1:13 PM

  147. Re: Climate Sensitivity

    In response to David Archibald, Gavin wrote, “You need to do it on a global basis as discussed here – and those estimates (all drawn from observations) give numbers near 3ºC for 2xCO2.” (inline to 140)

    Paleoclimate records say roughly 3 C.

    Please see:

    James’ Empty Blog
    Climate sensitivity is 3C
    by James Annan
    Thursday, March 02, 2006

    Thats evidence – not something dropping out of models.

    Comment by Timothy Chase — 15 Oct 2007 @ 1:43 PM

  148. lgl, So, what is the mechanism for your effect. How do you know that the causal arrow doesn’t point the opposite direction. Correlation is not causation. Correlation + an understood mechanism is a whole helluva lot closer.

    Comment by Ray Ladbury — 15 Oct 2007 @ 2:34 PM

  149. Ray,
    The mechanism is simply the winds and currents in the Pacific. For the last 30 years they have allowed less cold water from the deep to reach the surface. Then of course you ask for the mechanism behind that.
    Maybe the three large volcanic eruptions play a role. It looks like about 5 years after those there are very strong El Ninos. In fact, the three stronges El Ninos after 1950 come 5-6 years after these three eruptions.

    Comment by lgl — 15 Oct 2007 @ 4:01 PM

  150. lgl (#144) wrote:

    Sorry guys but all the model you need is this:
    El Nino add 0.2 oC, La Nina subtract 0.2 oC, and correct some for large volcano eruptions.
    GISS data for low latitudes:
    clearly show the stepy nature of the temperature rise.

    That’s called natural variability – and it don’t look “stepy.”

    lgl (#144) wrote:

    During periodes with more La Nina events than El Nino events, the temperature drops,
    where they are in balance there is almost no change, and when El Ninos are in majority the temperature rise:

    Why is it that the two charts don’t look the same?

    Comment by Timothy Chase — 15 Oct 2007 @ 4:14 PM

  151. Timothy,

    Subsequent to your comments, I have been having a bit of a look at how LW radiation passes through the atmosphere. This has led me to wonder whether people are using the correct interpretation of Beer’s (Beer-Lambert) law given the geometric considerations. Hopefully they are! A naive application would seriously underestimate the extinction of direct earth surface radiation. The geometric considerations I have considered is that the outbound “beam” is isotropic and hence the extinction is much faster than a simplistic application of that law would predict.

    I apologise that I have not as yet found the time to answer ,ost of your comments.

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 15 Oct 2007 @ 5:32 PM

  152. LGL, Well, I’ve got to hand it to you. You have come up with a theory even more half-baked than the the Galactic-Cosmic-Ray claptrap. You really need to do some research on ocean circulation. First the upwelling associated with the ENSO is a relatively small portion of the total deep ocean upwelling. It is not driven mainly by wind, but by differences in density and thermal effects. You can read about this here:

    Second, Global Climate Models include ocean circulation. Gavin has written on the subject here on RC.
    Now, most important, where are you getting these ideas? If you came up with them yourself, then I have to ask you why you reject a perfectly good model in favor of one you haven’t really worked out. What you have done is try to explain something you don’t understand in terms of something else you don’t understand. That’s not how science works.
    If on the other hand, you have read this elsewhere, the question is whether they really say this or whether you have misinterpreted the theory. However, the question still stands: Why reject a perfectly good theory in terms of something less than half worked out?

    Comment by Ray Ladbury — 15 Oct 2007 @ 8:02 PM

  153. Alexander Harvey (#151) wrote:

    Subsequent to your comments, I have been having a bit of a look at how LW radiation passes through the atmosphere. This has led me to wonder whether people are using the correct interpretation of Beer’s (Beer-Lambert) law given the geometric considerations. Hopefully they are! A naive application would seriously underestimate the extinction of direct earth surface radiation.

    Beer’s isn’t supposed to apply that well in the atmosphere I believe due to changes in pressure and temperature with altitude.

    Alexander Harvey (#151) wrote:

    The geometric considerations I have considered is that the outbound “beam” is isotropic and hence the extinction is much faster than a simplistic application of that law would predict.

    I suppose so – but I thought that Beer wasn’t dealing with the isotropic inverse square thing, just a straight beam, wasn’t he?

    Alexander Harvey (#151) wrote:

    I apologise that I have not as yet found the time to answer most of your comments.

    With regard to Kirchoff’s, he derived it from thermodynamic equilibrium but it has shown that the law applies quite well within LTE. Doesn’t depend upon radiation equilibrium.

    The thought is that one derives Kirchoff’s law:

    Emission over absorption is…

    εν(T)/κν(T) = Bν(T)

    … where εν(T) is the emission coefficient for frequency ν at temperature T, κν(T) the absorption coefficient for frequency ν at temperature T, and Bν(T)

    This is done for a thermodynamic equilibrium by means of the thought experiment involving a narrow band passive filter between two chambers. The filter is such that the only radiation between the two chambers is at ν (to ν+dν), but does so without performing any work. (Hence the name.)

    Given thermodynamic equilibrium, the chambers are assumed to be the same temperature. Now there can be no net radiation carrying net power as this would result in a rise in temperature in one of the compartments leading to a cooling of the other.

    However, the temperature of the radiation field Bν(T) is independent of the materials which the two chambers are made from and the temperatures of those materials, but the emissivity and absorption coefficients depend only upon the materials and their temperatures and are independent of the radiation field. Consequently Kirchoff’s law holds for any emitting and absorbing material so long as it is in thermal equilibrium – without regard to whether it is in equilibrium with the radiation field.

    That’s the condition of a Local Thermodynamic Equilibrium. (Of course all bets are off when the two chambers are at different temperatures.)

    Anyway, still have more to figure out…

    Comment by Timothy Chase — 15 Oct 2007 @ 8:23 PM

  154. Ray and Hank,

    Yes, but as you get to higher energy levels 1) the probability of a particular transition gets a little less, but, more to the point, 2) the now closer spaced lines do in fact form a continuum but this is within a relatively small bandwidth; no where near “continuous” ala Planck function.

    I think it is charge acceleration rather than mass movement that generates radiation. But, Hank, your point is well taken. But it is the (odd?) movement/acceleration of a gas molecule, which is not limited in its movement, not its internal jiggling (vibration, rotation, electronic), which is, that generates a continuous Planck function radiation. They just generate teensy tiny amounts if they are sparse and cold.

    Comment by Rod B — 15 Oct 2007 @ 10:11 PM

  155. Gas or liquid or solid, at any temperature, as long as it’s dense enough that interactions modify the movement a solitary atom or molecule can make.

    Plasma at high temperatures like the Sun, again because interactions modify the movement a solitary ion or atom or molecule can make.

    For a molecule, the bending or rotation or vibration isn’t just in its simple isolated clear form when there are other molecules interacting. Look at how water behaves as a vapor versus as a liquid versus ice — the bending motions are going to be very different when the molecules are interacting. Same for CO2 as a solid or very dense gas, the motions are going to be different than they’d be for a single isolated molecule.

    Comment by Hank Roberts — 15 Oct 2007 @ 10:41 PM

  156. Timothy,

    I think stated, as you have done, in terms of emission and absorption coefficients it is all much clearer. Really all that remains is to relate these terms to the underlying mechanisms. Firstly the Einstein coefficients and then the various forms of spectral line broadening.

    Regarding Beer’s Law: Providing you can integrate the absorption coefficient along each path and take account of the densities, pressures, etc. along that path to give the optical depth (d) of that path we have the proportion that is transmitted along the path equalling the exponential of -d


    One then has to integrate over all the paths, it is this last stage I was referring to.

    Geometrically the atmosphere is a thin layer over a large curved surface and it is not a simple matter to perform the integration. At a first approximation I think you get a transmittance equalling

    EXP(-d) + d*Ei(-d)

    where Ei(x) is the Exponential Integral and is negative for negative x.

    This tends to zero much faster than the EXP(-d) term alone.

    I think that a naive application of Beer’s Law to the atmosphere whether formally or merely when thinking about it would lead to poor outcomes. That is what I was trying to say.

    Which brings me back to the original topic of this thread. It is all too easy for anyone (amateur or professional) to misapply a technique, or a model, or a law, or a result, and come up with misconception.

    Personally I should like to see more transparency from all quarters. (Not just the atmosphere ;) )

    I think it is important that the details, both method and data, are clearly stated so that they can be checked in every detail. I doubt that peer review stretches to checking the data, identifying the unstated assumptions, checking all the physics and equations and reworking the calculations. I would think that the combined brainpower of the contributors here along with the disciplines we all enjoy would be sufficient to review some of the papers in depth providing the data and methods were provided.

    Even the most respected authors allow mistakes to occur in their work and are possibly never the wiser.

    There is much that I should like to see gone over with a fine-tooth comb. Not because I expect foul play but that I feel the results are so important that they should be beyond reasonable doubt.

    The same is true of models.

    I should feel much happier if I knew what assumptions go into MODTRAN or any of the climate models. Are these assumptions written down anywhere?

    At this moment I should like to see a list of the assumptions and the formulae that go into the calculation of the forcing due to a doubling of CO2. As I understand it, the figure is based on a lot of assumptions or facts about the state of the atmosphere and the properties of gases. Is this underlying information available? I would be obliged if someone could point me to it.

    Just as important is the limits of applicability of laws, methods and values like the CO2 forcing figure.

    As I understand it the CO2 forcing value is an ad hoc one. I.E. it applies to the current atmosphere. E.G. it has taken into account current amounts of cloud cover, water vapour, albedo and importantly temperature etc. If so could it be applied to ice age conditions or is a different value used. Are the limits on this values applicability stated.

    There are many things I should like to know, and to know in great detail.

    I ask this: can anyone shed any light on the applicability of the CO2 forcing value and the assumptions that have gone into its production?

    Best Wishes

    Alexander Harvey

    Comment by Alexander Harvey — 16 Oct 2007 @ 6:37 AM

  157. Rod, keep in mind that the blackbody distribution is the equilibrium distribution for a photon gas–it’s what the photon gas will approach provided there is sufficient interaction with the matter in its vicinity. Yes, free charges will radiate if accelerated, but what is doing the accelerating? Also, keep in mind that the energy emitted by an accelerating charged particle also has its own characteristic spectrum (e.g. bremsstrahlung, cerenkov, etc.). The point is that ALL of these processes can push the system toward the blackbody spectrum, and they will keep pushing it until it gets there (or arbitrarily close), because that is the equilibrium condition for the photon gas.
    Consider Earth’s atmosphere. To start with, we have more IR photons that would be found at equilibrium for that temperature, so the GHGs absorb IR photons. And preferentially, the relaxation process is via collisions with other molecules, so the gas heats up and the photon gas cools down. If the ghgs srarted out with the same energy as the photon gas, you would also have vibrational modes being excited collisionally and some decaying radiatively–equilibrium, and the number of photons would stay the same, as would the ghg temperature. And if the ghgs had a higher temperature, you’d have net energy flowing from there to the photon gas. This takes place in the absorption bands of the ghgs because that is where the photons can interact. Outside these bands, the atmosphere is inert, and you see the photons radiating from Earth’s surface.

    Comment by Ray Ladbury — 16 Oct 2007 @ 8:10 AM

  158. Re 150&152#

    I’m not rejecting any theory, but the ghg theory is not a perfectly good theory. With ENSO you have a good correlation but not a well understood mechanism. With ghg you have almost no correlation but a understood mechanism. The only correlation you have is that both ghg concentration and temperature is higher now compared to decades ago. I’m just searching for a better correlation. For instance, how can the heat generated by ghg after 1983 have been stored away for 15 years and then suddenly appear in 1998? You probably end up with the ocean currents there too and need to understand those mechanisms to fully explain the ghg theory.
    There is also a problem with the arctic amplification. The seaice coverage started to decline way back in the fifties, so it’s more likely a feedback of the solar forcing before 1950 and not a feedback triggered by ghg.
    Timothy, I don’t see what you mean. I picked the span from 1975 because it’s the more interesting. If you start from 1950 you will still see a close to perfect correlation, with the decline up to 1975 because in that time span La Ninas were in majority.
    And natural variability. So 0.4 oC rise in 8 years is a natural variability but 0.6 in 30 years can not be natural variability?

    Comment by lgl — 16 Oct 2007 @ 10:12 AM

  159. Hank, I think your 155 is correct. (At least I think I agree, which might not be the same thing…[;-) The internal molecular energies (vibration, rotation, electronic) are still limited by virtue of their quantization. True, those energy levels are far more active if there’s a lot of other molecules in the area that can collide and transfer energy in and out. True, also, that you get magnitudes more molecular activity in solids and liquids that in gases. Do we have a disagreement here?

    Comment by Rod B — 16 Oct 2007 @ 11:17 AM

  160. Ray, I pretty much agree with your 157. I hope I’m not dreaming [;-). One clarification: the example radiation types can also include PVF — plain vanilla flavor. And one nit-pick (to the point of near insignifance): a photon gas has a characteristic temperature, not a “real” temperature, so can’t really “cool down”. Though your point is valid.

    Comment by Rod B — 16 Oct 2007 @ 11:32 AM

  161. Hello, Gavin? Would you ask David Archer to take a look and see if we’re making sense as we seem to be reaching agreement on the words we’re throwing at this question?

    [Response: Sorry, I was tuned out for a bit. I think you’re right, that acceleration of the charge by bond vibration drives the absorbtion / emission band, but at high pressure, interactions among molecules tend to broaden the frequencies of light that can be emitted or absorbed. This thread has many fibers in it, however, so I’m not sure if I’m responding to the words that you’re asking about. I should also caveat that I’m an ocean chemist, not an atmospheric radiation physicist. I just posted MODTRAN and use it to teach, at about this level; I’m no authority on the details. David]

    Comment by Hank Roberts — 16 Oct 2007 @ 3:28 PM

  162. lgl, do you have any science background? If you don’t have a mechanism, you have precisely butkis! See:

    In a system as complicated as Earth’s climate, you of course have to take many factors into account. When you do (for example in global climate models) you get very good agreement with what is occurring. Look at the magnitudes of the energies involved–a simple model like yours does not come close. Again, I ask, where are you getting your information. It sounds vaguely like some of the organic matter a certain Hurricane expert from Colorado has been spewing.

    Comment by Ray Ladbury — 16 Oct 2007 @ 4:27 PM

  163. Rod B. The temperature of a photon gas is as real as any other temperature thermodynamically–the partial of energy with respect to entropy holding volume and photon number constant (which of course you can’t).

    Comment by Ray Ladbury — 16 Oct 2007 @ 4:29 PM

  164. lgl, you have also not answered my question as to why you think causality points one way and not the other. Why should the number of El Ninos start changing? What is driving that? I say again, you are explaining something you don’t understand in terms of something else you don’t understand. That is not science.

    Comment by Ray Ladbury — 16 Oct 2007 @ 4:37 PM

  165. “Bupkes” is the accepted spelling of that particular Yiddishism. :)

    Comment by Barton Paul Levenson — 17 Oct 2007 @ 7:48 AM

  166. Ray, I’m obviously not a scientist. I’m getting my information mainly from the GISS web pages, and definitely not from a Hurricane expert from Colorado. To me the correlation between temperatur and ENSO is obvious, when there are more El Ninos than La Ninas (or positive ENSO I guess) the temperature rise rapidly. This is not something I’m making up, the GISS page I linked to clearly shows this.
    The mechnism behind I do not know but would very much like to know.
    But you have not answered my question.
    How can the heat generated by ghg after 1983 have been stored away for 15 years and then suddenly appear in 1998? What mechanism is that in the “perfectly good theory”?
    I don’t understand your “why you think causality points one way and not the other”
    El Ninos means rise in temp and La Ninas means drop but that can’t be what you refer to.
    (And sorry for my bad English, you probably know by now it’s not my first language)

    Comment by lgl — 17 Oct 2007 @ 9:09 AM

  167. Barton,
    I stand corrected. Thanks.

    Comment by Ray Ladbury — 17 Oct 2007 @ 9:44 AM

  168. LGL–I don’t even understand your question. The heat didn’t get stored–it was warming the planet all along–as the temperature rise over that period shows. 1998 was in the middle of a pretty deep El Nino. See:

    Now if you are talking about the seeming hiatus in warming from ~1945 to the mid 70s, that is well understood. The fossil fuels burned in this period generated a lot of aerosols as well as CO2. The aerosols blocked sunlight, so during this period there was little net warming. So what happened during the 1970s? Clean air legislation decreased particulate, sulfate and other aerosols. Since aerosols have a short lifetime in the atmosphere, while CO2 lasts for hundreds of years, the CO2 really kicks in about this time. Global climate models have reproduced this effect, and the eruption of Mt. Pinatubo provided additional constraints.

    The issue of causality is important. If as you claim climate change were driven by the relative # of El Nino vs. La Nina, then we have to ask why this changed. There must be some underlying cause. On the other hand, with anthropogenic greenhouse gases, we know what changed–we dumped about 40% more CO2 into the air–we know that has happened because we did it. So if you can’t point to the underlying causes of the changes in the ENSO, isn’t it more likely that climate change could be behind these changes rather than the other way around?
    Changes don’t just happen. Energy doesn’t just come from nowhere. The energy flow related to the ENSO does affect the energy in the climate system, but these effects are rather short term. The energies involved aren’t that large. On the other hand, greenhouse gases provide several watts per square meter over the entire surface of Earth.

    Other criticism of your theory: Why would it cause night-time temperatures to rise more than daytime temperatures? Why would it cause Winters to become shorter? Why would it have more effect at the poles.

    That is why if you don’t understand the mechanism, you have “Bupkes” (as our good friend Barton counsels).

    Comment by Ray Ladbury — 17 Oct 2007 @ 11:28 AM

  169. Ok, if I’m the only person seeing this correlation we can leave it there. In a few years we will probably see a long lasting negative ENSO, then this will be much debated.
    Other criticism. All that you mention here is probably the nature of a warmer planet, no matter cause.

    Comment by lgl — 17 Oct 2007 @ 1:04 PM

  170. Why is the temperature dropping in the Southern Hemisphere? Why is it approaching only a .2C rise in temps since the 1940s?

    Is CO2 dispersed differently throughout the atmosphere?

    Why is it still cooler than 1934 in the USA?

    Comment by Bruce — 17 Oct 2007 @ 7:19 PM

  171. Bruce, you know, you can find much better and more thorough answers to your questions by perusing some of the editorial content on this site. They’ve all been dealt with in detail.
    However, in brief:
    Southern hemisphere–google a map of the globe. See all that blue stuff in the Southern Hemisphere? That’s water, and it’s one heckuva heat resorvoir. That goes a long way to explaining your question.
    And wrt 1934, no one has claimed that a single factor determines climate. And no one responsible would make claims based on a single year. But how about the fact that 13 of the warmest 20 years since we’ve had records (~120yrs) have been in the last 20 years. That, sir, is called a trend.

    Comment by Ray Ladbury — 17 Oct 2007 @ 8:15 PM

  172. Does anyone know where i can get accurate data on the total emissions (daily, yearly) of the world? Not just greenhouse gases? The number is probably in the billions of tons/day. The skeptics need to answer what effect this is having. And if glaciers are truly thousands of years old and are truly melting, this should end any 1500 years cycle debate, end of line. If it’s fact that the sun is warming (or any other natural cause),is this not all the more reason to limit our emissions? Sorry if this is the wrong place, digging through all the media lies is exhausting and this site is a bright star.
    The environment is in sad shape and it’s becoming obvious that the future of our species cannot be left in the hands of capitalists.
    Thank you for this site by the way.

    Comment by p n reynolds — 20 Oct 2007 @ 10:21 PM

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