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Why the continued interest?

Filed under: — rasmus @ 9 October 2009

I believe the idea that galactic cosmic rays (GCR) play a role for the present global warming is unlikely to fade soon, despite a growing number of scientific arguments that normally would falsify a hypothesis and lay it dead (see links here and here). Despite all the arguments against the role of GCR, there was a solicited talk about ‘cosmoclimatology’ at the European Meteorological Society’s (EMS) annual meeting in Toulouse. Henrik Svensmark is further invited by the Norwegian Academy of Science and Letters (NASL) to provide an introduction to their seminar on climate. So why is the GCR-hypothesis still perceived as an interesting explanation?

My impression from the solicited talk, is that the confidence in the GCR hypothesis now rests on two points that were made explicit in the presentation, and that we have not adequately addressed here. So, here they are:

Point I: When I asked Svensmark why he presented a curve describing low cloud-cover from the ISCCP – used for correlation study with GCR (link) – that differed from the curves presented at the ISCCP web site (link), he informed me that he used a corrected version that has been published. Nevertheless, the ‘correction’ of the curve is controversial, and the ISCCP team is clearly not convinced, despite the likelihood of instrumental degradation.

Good practice would then be to present all the curves that cannot be ruled out because of errors. When asked why he didn’t present the other cures too, he said that he only wanted to show the one curve. Not a very convincing answer, and not very reassuring.

Point II involves a ‘remarkable’ correlation, meant to demonstrate a link between high GCR flux and cold conditions. This analysis is based on a comparison between band-pass filtered ice-rafted debris from iceberg drifts (Bond, 2001) and Carbon-14 (a cosmogenic isotope) over the last 12,000 years (e.g. after the most recent ice age).

The relationship between temperature and drifting icebergs, however, is complicated and not so straight forward. Icebergs are formed when chunks of ice break off glaciers and icesheets – a process known as ‘calving’.

On the one hand, icesheets and glaciers grow when the accumulation of precipitation at below freezing temperatures (snow) exceeds the summertime melting. Very low temperatures, tend to be associated with low precipitation, however. One the other hand, iceberg calving does not require very low temperatures (as long as the ice is present), but is favoured by reduced friction at the base of ice caps, resulting in a faster flow towards the sea. Melt water can lubricate the ice sheets and hence affect the ice flow.

Once the icesheets have calved and produced icebergs, they will drift according to the winds and ocean currents. The most influential ocean currents for iceberg drift in the North Atlantic include the East Greenland Current EGC), which follows the east coast of Greenland and flows from northeast to southwest, the West Greenland current (WGC) into the Labrador Sea, and the Labrador current (LC), a coastal current following along the perimeter of the Labrador sea basin in an anti-clockwise fashion.

North Atlantic ocean current systems Many of the cores used to study the ice-rafted debris were from locations away from these currents. It is not clear whether anomalous cold conditions produced more southerly winds and ocean currents. However, many of the core locations are associated with a surface flow from the south in the present climate, so it is possible that the icebergs transported by the EGC, WGC, and LC end up in the North Atlantic current. One explanation is that the icebergs got caught in the warm currents from the south, and melted on their way north, but that does not necessary imply cold conditions in that region, as these warm ocean currents provide a heat transport and the melting of icebergs suggest higher temperatures.

Cold conditions favour the formation of sea-ice, which have very different characteristics to icebergs. Sea-ice forms when the sea surface freezes, and can affect the ocean circulation through their effect on salinity. However, sea-ice does not create debris of rocks and minerals, as the icebergs do when the bottom of the sliding icesheets scrape the rocks.

It is plausible that very cold conditions can produce thick sea-ice that will lock icebergs in place near their sources in the Labrador sea and along the east coast of Greenland, but seasonal variations in the sea-ice may also imply open water in the summer. Nevertheless, very cold conditions may not necessarily favour the production of icebergs, as freezing temperatures will prevent the formation of melt water acting as lubrication and the accumulation of ice is expected to be less due to lower precipitation.

In summary, the ‘remarkable’ correlation does not seem to support the hypothesis that high flux of GCR produces a very cold climate. The question is rather whether the ocean and atmospheric circulation were influenced by the level of solar activity and associated changes in the total solar irradiation (TSI) – without involving GCR. After all, GCR is affected by the level of solar activity through its influence of the inter-planetary magnetic field, and anti-correlated with the sunspots.

When taken in the context of the global warming, there are other problematic issues such as the lack of trend in GCR (here and here), stronger warming during nighttime than daytime, large unknowns regarding the physical mechanisms involved in the growth of ultra-small molecule clusters to much larger cloud condensation nuclei (here and here), and questionable data handling and statistical analysis (here). In addition, it is difficult to statistically distinguish between the apparent response to solar forcing in the observations and GCM which do not take GCRs into account (link to a recent paper by Gavin and myself), implying that GCRs are not needed to explain past global temperature trends.

So what makes the GCR-hypothesis so convincing that warrants a solicited talk at the EMS annual meeting and an invited presentation at the NASL? Is the support based on the attention in media, or does it have a scientific basis?

I want a response from the community still supporting the GCR hypothesis, explaining why they find it convincing after all these misgivings. The spirit of science is about discussing different ideas and challenge unconvincing points of view. So far, I feel that many of these issues have gone unheeded outside the climate research community. Perhaps an improved dialogue between various research communities can help resolving these issues – the counter-arguments and GCR hypothesis represent a paradox that should be sorted out if the science is to progress. Either the supporters of the GCR hypothesis should convincingly explain why these misgivings are unfounded or irrelevant, or the GCR hypothesis should be buried. However, I feel that there is a lack of dialogue and willingness to listen, so I think that progress is not likely to happen regarding a commonly accepted solution on the GCR hypothesis.

Update: According to a recent (October 16) news relsease from the International Ice Charting Working Group (IICWG), over 1,200 icebergs drifted into the trans-Atlantic shipping lanes in 2009, making the iceberg season in the North Atlantic the eleventh most severe since the tragic loss of the RMS Titanic in 1912.

P.S. So far in 2009, three articles have been published in the arXhive on GCR and clouds (here, here, here). It is possible that such articles are more accessible to communities other than climate research, and hence enhances the awareness about the controversy surrounding the GCR-hypothesis.

506 Responses to “Why the continued interest?”

  1. 301
    Mark says:

    Paul thiers, you can find him asking for people to contact him on

    http://scienceblogs.com/deltoid/2009/05/open_thread_27.php

    Given that he thinks the ocean accounts for 80% of the warming but has not asked himself “where did that warming come from” and checked if his hypothesis is right, and states that the past few years has seen as much cooling as the warming of the last 50 years (which isn’t shown in any temperature reading of the earth’s surface), I would discount what he says.

    He does a lot of grandstanding, too:

    http://omniclimate.wordpress.com/2009/09/21/monbiot-challenged-to-debate-by-chills-peter-taylor/

    which just happens to help sell his book.

  2. 302
    Mark says:

    PS A common troll on deltoid counters any suggestion that they are biased by saying “I read the Guardian!”.

    I would place Peter’s protestations that he isn’t a denier because he does some consulting work for Greenpeace in the same basket.

    It’s proof of nothing.

  3. 303
    Ray Ladbury says:

    I am afraid I misunderstood Millett’s argument, perhaps because what he is arguing against is simply accepted physics–not at all controversial. If you are correct, he seems to be arguing against all of radiative physics–from Stefan-Boltzmann to the very concept of a black/gray-body radiator.

    My apologies for failing to comprehend that he could actually be that stupid.

  4. 304
    pjclarke says:

    I wonder if any of the experts on this site can give me any information about Peter Taylor, author of the book “Chill.”

    I am no expert but I do read blogs! Recently Mr Taylor popped up in the comments at George Monbiot’s blog in the aftermath of the Plimer debate no-show, offering to debate Mr Monbiot. He gains credibility points for a Natural Sciences degree from Oxford, a record of environmental activism, sitting on several well-regarded scientific and environmental committees and for writing a book describing his views. According to one reviewer the book has ‘brave words from a career environmentalist who has managed to keep his head when all around him are losing theirs.’. The blurb also contains this ‘At the very least, Taylor raises issues and questions that must be addressed conclusively before global warming can be genuinely regarded as truth, inconvenient or otherwise. This book is a must-read for everyone on all sides of the climate change issue.’ – W. Jackson Davis, professor emeritus, University of California, and author of the first draft of the Kyoto Protocol’

    But he loses credibility for some embarassing factual errors, also by proposing Monckton as an authority on climate sensitivity. Although his conclusions are based on ‘his studies of satellite data, cloud cover, ocean and solar cycles’ none of these studies is apparently worthy of publication, other than in this non-peer-reviewed book. I for one will not be spending £14.99 on ‘Chill’ – his main thesis seems to be the IPCC underestimates natural cycles and variability which I think is demonstrably false. There is a pdf appendix available online that repeats the ‘warming pause’ canard among others, he also captions a graph that is clearly from woodfortrees.org as ‘excellent source material provided by Anthony Watt.’ (sic) which does not exactly inspire confidence.

    Author Profile:http://www.clairviewbooks.com/pages/viewauthor.php?id_in=29

    He participates in a blog thread here, including email exchange with Monbiot …
    http://ccgi.newbery1.plus.com/blog/?p=220&cp=all#comments

    Appendix http://www.ethos-uk.com/downloads/books/chill/CHILLAppendices.pdf

    Video: http://www.youtube.com/watch?v=UUUYcfsaSnw

    Phil Clarke.

  5. 305

    #282 Rod Black

    Context is still key. You seem to enjoy every opportunity to nitpick at someone’s blog post who is trying to help someone understand things (#160 Pekka Kostamo).

    What I, arrogantly or not, think you need to assimilate into your thinking process is context and relevance. You have ignored evidence time and time again. What a terrible reputation you have in showing how truly unreasonable a person you are. Is that really the legacy you wish to foster.

    The main argument about global cooling centered around the 1975 NAS report. The media took pieces of the report and quoted them out of context. Have you actually read the global cooling papers from the 70’s? I have not, so I really can’t speak specifically, but it is clear that we are not cooling so they were wrong. Simple as that. Therefore those papers have various degrees of irrelevance in the context of the main argument re cooling/warming.

    Your statement,

    I never have understood why you (guys) deny the number of scientists and scientific publications (Science for one) that supported (more or less) the “global cooling” of the 70s.

    , illustrates that you continue to ignore context and relevance, hence my assertion as to your immature views in your general argument presentation. In other words, grow up… please. You are really boring, and wasting peoples time… but I’m confident that does not concern you.

  6. 306
    Richard Steckis says:

    Mark 293 says:

    “We also know from measurements that the climate is sensitive to CO2 doubling in a range that the models with their “faulty” clouds agree with.”

    Cite references please. Which measurements? Are they from empirical research or just from more modelling?

  7. 307
    Mark says:

    “Is that really the legacy you wish to foster.”

    It could be.

    After all, there are people out there working in marketing who “know” that they are buying the services of spammers. They don’t ask, so it’s only quote know unquote.

    Rod B could easily be doing the same thing. Either because that’s what he’s paid for, what he *thinks* he gets paid for (workers for oil companies probably convince themselves that there’s no problem with CO2 for example) or he doesn’t WANT CO2 to be a problem and refuses to investigate his queries to see if there’s a denialist lurking in his soul, just so that he doesn’t know he’s a denialist.

  8. 308
    Hank Roberts says:

    The ‘cold atmosphere’ phrase suggests a case of Gerlich-Tscheuschner, perhaps the variety transmitted by Marohasy and Siddons.

    jennifermarohasy.com/blog/2009/04/on-the-first-principles-of-heat-transfer-a-note-from-alan-siddons/

    That one has been amply refuted (Rabett, Deltoid, basic physics texts) and the notion that heat can flow only one direction belongs on a FAC list (frequently asserted confusions). I’ll ask over at skepticalscience, I don’t see it listed.

  9. 309
    Mark says:

    ““We also know from measurements that the climate is sensitive to CO2 doubling in a range that the models with their “faulty” clouds agree with.”
    Cite references please.”

    Using multiple observationally-based constraints to estimate climate sensitivity
    J. D. Annan and J. C. Hargreaves

    Observational constraints on climate sensitivity
    Myles Allen, Natalia Andronova, Ben Booth, Suraje Dessai, David Frame,
    Chris Forest, Jonathan Gregory, Gabi Hegerl, Reto Knutti, Claudio Piani,
    David Sexton, David Stainforth

    It’s been done on this site before many, many times, Rod B. The Annan paper specifically and the RC threads talking on this subject included these and other papers.

    But I guess the four-year-old just can’t remember before this morning, can it.

  10. 310
    t_p_hamilton says:

    Mark 293 says:

    “We also know from measurements that the climate is sensitive to CO2 doubling in a range that the models with their “faulty” clouds agree with.”

    Steckis asks:”Cite references please. Which measurements? Are they from empirical research or just from more modelling?”

    If only there was a website about climate that you could search “climate sensitivity”. I suppose the world may never know.

  11. 311
    bushy says:

    Mark, whoever you may be, the point of science is to arrive at an acceptable explanation of the subject in hand and if that does not work out, move on and research some more ad infinitum. Your continuing attacks on all who disagree with your particular view is boring and sad. I am sure that Gavin and Michael are both actively and continuously looking at all aspects of the science and new information as it comes to hand. There is no need to badmouth folk because of their current perception of the state of the debate, and debate it is, because we are nowhere near arriving at the truth no matter how you spin it. Keep it up researchers and good luck.

  12. 312
    Rod B says:

    dhogaza (289), I presented nothing. I corrected someone else’s. I was correct. What’s your excuse?

  13. 313
    Rod B says:

    Ray Ladbury (300), why do you make me explain simple things over and over again? Assertion was that there were NO (that’s none; zero if you like; nada if that’s more familiar) published papers supporting the expected “global cooling” in the 70s. I stated accurately that this was wrong. Nothing was said or implied about aerosols, M cycles, consensus, or anything else that you keep debating with me over.

  14. 314
    Hank Roberts says:

    Rod, you keep claiming, if I understand what you keep writing, that there is a science journal paper “supporting the expected ‘global cooling’ in the 70s”

    Citation needed — what is it you see that was
    “supporting the expected ‘global cooling’ in the 70s” — precisely?

    What paper? What authors? Published where and when?

    Don’t just wave your arms. Tell us what– exactly–you believe to be true.

  15. 315
    Mark says:

    RodB 313, Did you really say that?

  16. 316
    dhogaza says:

    dhogaza (289), I presented nothing. I corrected someone else’s. I was correct. What’s your excuse?

    Really? This is what you responded to:

    If you refer to the 1970’s “ice age scare”, it is all bogus. Just sloppy reporting by the press, nothing in the scientific publications.

    And that’s a true statement regarding the “ice age scare” as the denialsphere talks about it today, i.e. the claim that in the 1970s scientists were claiming we were entering an ice age over the *short term*.

    Maybe you can find us a paper that predicted north america would be mostly covered in ice, by, say, 2050 and prove us wrong.

  17. 317
    Mark says:

    “There is no need to badmouth folk because of their current perception of the state of the debate,”

    No, I agree.

    But there IS a need to tell people off who continuously and malignantly fail to listen because they don’t like what they’re being told.

    Like Bob bob.

    “because we are nowhere near arriving at the truth no matter how you spin it. ”

    And you.

    What do you mean “nowhere near arriving at the truth”? 2-4.5C warming per doubling with all the model inputs matches pretty acurately what reality with all it’s “scary unknowns” (that denialists like yourself and RodB like to cast it as) says it is.

    How much closer to the truth do you have to get before you start accepting that the models are damn good? When they can tell us when the first raindrop to hit your head will happen???

  18. 318
    Mark says:

    PS Bushy, maybe you ought to go here and see what the other side get up to on their day off:

    http://scienceblogs.com/deltoid/2009/10/blog_action_day.php

  19. 319

    #311 bushy

    You may be “nowhere near arriving at the truth” but the major forcings are well understood. Your statement is vague and inappropriate in the context of the well understood science. The less understood science will help refine the view, but that does not diminish in anyway that we ‘know’ this global warming event is human caused with extremely high confidence form a scientific point of view.

    I also find it odd that you state “we”. Do you have any evidence to support the notion that you speak for everyone? Some sort of certificate perhaps?

  20. 320
    Patrick 027 says:

    John Millet – I read what he wrote too quickly, thinking of the solar heating of the surface + atmosphere (significantly more than 1/2 of backradiation) instead of the surface alone. But that’s beside the point, as I said earlier.

    Hank Roberts – “The ‘cold atmosphere’ phrase suggests “…

    We had that discussion here
    http://www.realclimate.org/index.php/archives/2009/03/olympian-efforts-to-control-pollution/comment-page-7/
    (started on page ?)

    and I went at it with the perennially ignorant Gord (who managed to warp both the first and second laws of Thermodynamics, and apparently dissaproves of algebra*) starting here:
    http://www.skepticalscience.com/argument.php?p=6&t=537&&a=18#2842
    (PS one way to make the case: imagine being inside an isothermal red-hot object with significant emissivity (at red wavelengths) in all directions; would you not see red radiation coming from all directions, or would it look completely dark for lack of temperature gradient?)

    Aside from that, of course there’s the RC wiki:
    http://www.realclimate.org/wiki/index.php?title=G._Gerlich_and_R._D._Tscheuschner

  21. 321
    Ray Ladbury says:

    Rod B., Exactly WHERE did someone say no scientists were concerned about aerosol cooling?
    Schneider and Rasool raised the possibility in 1971:
    “However, it is projected that man’s potential to pollute will increase 6 to 8-fold in the next 50 years. If this increased rate of injection… should raise the present background opacity by a factor of 4, our calculations suggest a decrease in global temperature by as much as 3.5 °C. Such a large decrease in the average temperature of Earth, sustained over a period of few years, is believed to be sufficient to trigger an ice age. However, by that time, nuclear power may have largely replaced fossil fuels as a means of energy production.”

    This paper is the one that gave rise to the famous NEWSWEAK (spelling intentional) article. However, note that his concern only arises for much greater apacity in the atmosphere. What is more this paper used a very limited climate model and a very low value for sensitivity. The fact we aren’t cooling is in fact one of many lines of evidence favoring higher sensitivity.

    Rod, if you are looking for hysteria, you won’t find it here.

  22. 322
    Ray Ladbury says:

    Bushy, Your use of “debate” is imprecise. What matters is what is under debate–and the role of CO2 in climate is not among such topics in scientific circles. Since science is the subject of this blog, continual appeals to long and repeatedly discredited arguments become tiresome quickly. While Mark is rather quick to strike out, his frustration is shared by those who know the science and even those trying to learn it.

  23. 323
    John Millett says:

    #277 “Really, in order to keep the surface at 33 degrees C above the blackbody temperature, there has to be 2 times the sun’s radiation coming from the atmosphere. Remember, the sun is a tiny bit of the sky, very far away. The atmosphere is wrapped around the earth, very close. That’s why we don’t die every night when the sun goes down…”

    Marcus, the sun is distant but powerfull. Like a pig on a spit, wrapped in our cold atmospheric blanket we rotate daily in its 1368 Wm-2 flux and 394K effective temperature (121C, 250F). We soak up enough of it during the day to keep us alive at night. Marcus, what if the number 33 was changed to 9 – what would be the back-radiation?

  24. 324
  25. 325
    Hank Roberts says:

    _that_ John Millet over at the Australian says:
    “… it’s not 33 degrees due to trace gases in the cold sky above, it’s 7-8 degrees due to hot rocks below…”

  26. 326
    Patrick 027 says:

    John Millet.

    Solar radiation in space – 1368 W/m2 or so. Okay, now divide that by 4 to get the average incident solar flux over the surface of the Earth (the surface of a sphere has 4 times the area as it’s circular cross section). Now multiply by 0.7 because 30 % of the incident solar radiation is not absorbed but reflected to space. The equilibrium temperature is then 255 K. (Qualification – variations in temperature allow the actual average temperature to be less because of the nonlinear dependence of blackbody radiation on temperature. However, for the temperature variations at the Earth’s surface, this only has an effect of about 1 K.)

    The atmosphere is somewhat opaque to LW radiation, so some of the radiation emitted to space comes from the atmosphere. There has to be a temperature difference between the atmosphere and surface to drive the radiative and convective fluxes that make the energy flow balanced. And so on for individual layers of the atmosphere.

  27. 327
    Jack Roesler says:

    Jeremy #3:

    I know at least one person who sticks by his assertion that global warming is “god’s will”. I’m sure if I asked more, I’d find more who think that as well.

  28. 328
    Hank Roberts says:

    Can we end this digression soon? The theme’s old, well battered and fried:

    http://rabett.blogspot.com/2009/03/fred-says-when-anonymice-comments-are.html

    “… Early Symptoms: An infected individual will often display the following symptoms within 24 hours:
    (a) Frequent and fevered claims to the effect of “a cold atmosphere can’t warm a hotter surface”….

  29. 329
    Ray Ladbury says:

    John Millett, What color is the sky on your planet?

  30. 330
    John Millett says:

    #297 Barton Paul Levenson
    Thanks for the reference which will take some time to digest. Whenever I’ve thought along those lines I figured that wave interference would play a part. Is it a comfort that the system stabilises? How many iterations?

  31. 331
    dhogaza says:

    John Millet spumes:

    Thanks for the reference which will take some time to digest. Whenever I’ve thought along those lines I figured that wave interference would play a part. Is it a comfort that the system stabilises? How many iterations?

    Yet, in Hank’s reference, he posits:

    The natural greenhouse coat fell off next – it’s not 33 degrees due to trace gases in the cold sky above, it’s 7-8 degrees due to hot rocks below. Finally, under close examination of the global energy budget, which reveals a self-falsifying AGW hypothesis, the trousers fall around the ankles.

    Which is it, John Millet? You’re sure of your “science” and have disproven the physics behind AGW, or not?

    If you’re not sure, why did you post such doo-doo elsewhere?

  32. 332
    Patrick 027 says:

    John Millet –

    Iterative methods can help illustrate the idea.

    Nothing against it, but I think it is also quite helpful to think of what it would look like if you could see at any particular wavelength.

    If you were enveloped by a white-hot opaque (at all visible wavelengths) object in which a sufficient portion of that opacity were absorptivity (as opposed to scattering/reflection), then you would see white light coming from all directions. But if the object is isothermal, there shouldn’t be any net flow of heat (At least not within it’s depths where opacity blocks radiation to and from the outside). No problem – the radiation you’d see is isotropic – it would be the same intensity in all directions, so that there would be no net flux in any direction (more precisely, the radiatiant intensity adjusted by some measure of index of refraction would be isotropic … same result, though; no net flow of heat).

    Now if there is a temperature gradient, there will be a net flow of radiant heat within the region that the temperature gradient can be seen – large opacity requires a larger temperature gradient to sustain the same net flow, and restricts the net flow of heat across a sharp jump in temperature into a smaller volume concentrated at the jump (so there will be stronger cooling and heating within a smaller volume). On the other hand, if there is a thin layer of material at a different temperature, then the net radiant fluxes near that layer caused by the temperature variation will increase from zero at zero layer opacity and approach a limit as the opacity increases, provided that a portion of that opacity is absorption.

    (This is not so important to Earthly conditions, but in general: Without any atmospheric LW absorption, a greenhouse effect can be caused by atmospheric LW scattering (or reflection if the ‘atmosphere’ had some thin interface, which would be odd for gaseous matter) – in that case, the atmosphere would scatter radiation emitted by the surface, and some of that would go back to the surface. The radiation that escapes to space would be less than the amount emitted by the surface – this can be visualized as a consequence of the partial backscattering of the darkness of space (the lack of radiation from space would be partly reflected – if this sounds odd, rest assured it (and the rest of this) can be formalized in terms of *’weighting functions’).)

    (PS for emission by processes at local thermodynamic equilibrium (LTE), at any given wavelength (and where important, polarization), along any given path over a given distance, absorptivitiy of radiation going in one direction = emissivity for radiation coming backward along that direction.)

    *Weighting function:

    At a given location, for a given wavelength and polarization, for radiation in a particular direction going through that location, the distribution of the absorption of that radiation is a distribution in space of absorption per unit volume (or per unit mass, if mass-related coordinates are used, etc.) This distribution is a weighting function, and the volume integral of this distribution is 1, because the total absorption is 1 * (*for these purposes, escape to a void with no return is like absorption – space absorbs the LW radiation from the Earth and the SW radiation reflected by the Earth – allowed sufficient time and distance, this ultimately is true.) If there is no scattering or reflection, this distribution is focused along a line, and for a given constant opacity along the length of that line, it decays exponentially away from the location. If there are partially reflective interfaces, the distribution will have branches. If there is scattering, the distribution will fan out from the line. Note that scattering and reflection tend to concentrate the distribution closer to the location; in the limit of strong isotropic scattering, the distribution becomes spherically symmetric about the location, assuming there is some nonzero absorption and any reflective or absorbing boundaries are sufficiently far away. Greater opacity from absorption will still concentrate the distribution toward the location even when scattering is important.

    AT LTE, the weighting function for emission of radiation going through the location in the opposite direction is identical to that of the absorption of radiation in the original direction. The intensity of the emitted radiation is equal to the volume integral of the produce of the weighting function and the blackbody radiant intensity at that wavelength for the temperature (which can vary over space).

    The net intensity at a location in a direction (for the wavelength and polarization) is the difference between emitted radiant intensities going in opposite directions and thus depends on the different temperatures found in the different weighting functions. And so on for a radiant flux through a unit area…(see next paragraph).

    A radiant flux in a direction per unit area (area of a plane perpendicular to the direction) is the integral over solid angle of radiant intensity multiplied by the cosine of the angle from the direction perpendicular to the plane. (Radiant intensity is the flux per unit area normal to a direction, per unit solid angle – the total flux per unit area is the sum of fluxes in different subsets of directions that pass through the unit area in the same direction. The cosine factor is a consequence of geometry. If you can get geometry, you can get radiation. To make radiant intensity more familiar, it is how bright something looks – ie if the sun were seen through a frosted glass window, assuming no reflection from the window, the same total flux would pass through the window, but it would look less bright because the rays of the sun will be scattered and spread into a larger solid angle of directions.)

    Except for the forward-scattered radiation seen coming from directions near the sun (CAREFUL!), the diffuse radiation from a clear sky (made of scattered solar radiation) generally appears brighter near the horizon because there is greater opacity in that direction – the volume of the atmosphere is glowing with scattered radiation, and looking through longer mass-weighted distances through the atmosphere, one can see greater intensity of that glow, up to the point that it would saturate.

    Analogous to that, generally, one would see greater intensity of LW backradiation from the atmosphere coming from nearer the horizon. There are some exceptions – under some conditions (clouds, humidity) or at some wavelengths, where there is sufficient LW opacity and there is a temperature inversion near the surface, the intensity of LW radiation will be greater for radiation coming more directly downward. If the opacity is not great enough, the inversion is less visible and the general decrease of temperature with height above it dominates. If there are wavelengths where the stratosphere is optically thick and the troposphere is not, then the LW intensity of backradiation could be dimmest near the horizon or at an intermediate angle – this might occur with some wavelengths where ozone is important – maybe – but is not the case at most wavelengths, because the stratosphere has less mass then the troposphere, water vapor and clouds are concentrated in the troposphere (water vapor in particular is concentrated near the surface, though the little bit at higher altitudes has importance), and because of the way optical properties of gases depend on pressure and temperature.

    Adding greenhouse gases concentrates the weighting function of radiation crossing the tropopause closer to the tropopause over various parts of the LW spectrum. At the ‘top of the atmosphere’, adding greenhouse gases concentrates the weighting function of emission to space higher up, removing it from the surface, and adding it to the stratosphere – whether the troposphere gains or loses parts of it depends on the initial optical properties – it will gain if starting from lower opacity, it will max out and then lose as opacity increases.

  33. 333
    Patrick 027 says:

    “but it would look less bright because the rays of the sun will be scattered and spread into a larger solid angle of directions.)”

    less bright per unit of your visual field.

  34. 334
    Patrick 027 says:

    The greenhouse effect for CO2 is not saturated because adding CO2 increases the width of the wavelength interval that surpasses a given level of tropospheric opacity.

  35. 335

    John Millett:

    Is it a comfort that the system stabilises? How many iterations?

    The Basic program stabilizes in four iterations if I use a temperature resolution of 0.001 K. Here’s the code (Gavin et al., sorry if this is a bit off-topic, but it’s relevant to the entropy associated with cooler and warmer objects radiating at each other):

    ‘=====
    ‘ Granite models the temperatures of two granite blocks interacting
    ‘ only by radiation.
    ‘=====

    Aplug = 90.7 ‘ A electrical power input.
    Bplug = 221.5 ‘ B electrical power input.
    sigma = 5.6704e-8 ‘ Stefan-Boltzmann constant.

    ‘—–

    Ta = (Aplug / sigma) ^ 0.25
    Tb = (Bplug / sigma) ^ 0.25

    maxA = 379 ‘ Arbitrary.
    maxB = 852

    print “Ain”, “Aout”, “Ta (K)”, “Bin”, “Bout”, “Tb (K)”

    cycles = 0

    while maxA > 0.001 or maxB > 0.001
    maxA = abs(Ta – lastTa) ‘ Temperature resolution so far.
    maxB = abs(Tb – lastTb)

    lastTa = Ta ‘ Previous value.
    lastTb = Tb

    Aout = sigma * Ta ^ 4 ‘ Stefan-Boltzmann law.
    Bout = sigma * Tb ^ 4

    Ain = Aplug + 0.01 * Bout ‘ 10 m, inverse-square.
    Bin = Bplug + 0.01 * Aout

    Ta = (Ain / sigma) ^ 0.25 ‘ Inverse S-B law.
    Tb = (Bin / sigma) ^ 0.25

    print using(“###.###”, Ain),
    print using(“###.###”, Aout),
    print using(“###.###”, Ta),

    print using(“###.###”, Bin),
    print using(“###.###”, Bout),
    print using(“###.###”, Tb)
    wend
    end

  36. 336
    Hank Roberts says:

    One last plea, folks.

    Rasmus created this to ask for feedback about a particular question from climate scientists. You can read that at the top of the page.

    Everything else is off topic — much of it inspiringly, creatively, may I even say professionally effective in distracting from Rasmus’s question.

    Gavin, I’d love to quietly read a parallel weblog: _Real_Climatologists_

  37. 337
    Mark says:

    Hank, not one has come on here.

    If we wait, we’ll hear the rustling passage of tumbleweeds.

    So we make do with what conversation and hypothesis for the continued interest we do get.

    Which is all about “well, they could be…”. Always “they”. Not “me”. But it’s all we’ve got to work with here.

    Maybe some of them will go along and ask. And, since they have been previously very pro GCR they may get the answer Rasmus hasn’t been getting himself.

  38. 338
    Hank Roberts says:

    > if we wait, we’ll hear ….

    Precisely.
    “… consider if what you are about to say will improve upon the silence.”

    http://www.tricycle.com/essay/skillful-speech

  39. 339
    Mark says:

    Ironic:

    Words or actions that have an effect opposite to their literal intention.

    :-P

  40. 340
    Jim Galasyn says:

    Why climate change denial must be taken seriously
    By Peter Gorrie, Science Reporter

    …This is the paradox and potential triumph of Not Evil Just Wrong, a new documentary that attacks the environmental “elites” and “extremists” who campaign for measures to curb climate change. The Irish husband and wife co-directors, Phelim McAleer and Ann McElhinney, are among those who argue policies to combat the build-up of greenhouse gases are not only unnecessary but also potentially calamitous.

    They present the familiar roster of skeptics and their readily rebutted scientific claims – that the poles and glaciers aren’t melting; it’s a happy time to be a polar bear; Pacific sandbar islands like Tuvalu will stay high and dry; and, in fact, the planet isn’t heating up after all.

    But none of those details really matter: Facts change few minds these days. American politics and policies – like Canada’s – increasingly rely on raw fear, anger and division.

    The film declares culture war: It pits Tiffany – whom McElhinney met in a pub while seeking human faces for her story – and other average Americans against unfeeling, wealthy elites – the likes of Al Gore – who want to rip away the slim hopes they cling to.

    “The elites of the world are making extraordinary decisions about what’s going to happen to ordinary people,” says McElhinney. …

  41. 341

    340 Jim Galasyn

    That is a very important article for us all to read. The Science Reporter carefully points out how important it is to bring the middle class into the debate on the right side.

    Those of us who believe there is a looming problem with CO2 have to contend with “deniers” as well as “wealthy elites” who take a callous attitude toward middle class values. Change has to come but it will not work out well if we are not careful.

    I bring up again the fact that plug-in cars, whether hybrids or all electric are a cruel green washing hoax. Cars running on electricity are cars running on coal until there is reserve capacity to tap to run them. The IEA recently put out an exerpt of one of their expensive reports that purports to show that there is a great benefit in electric cars but at the same time it shows that the reserve generating capacity in 2030 will still be coal. (Go to http://www.worldenergyoutlook.org/ and download the “exerpt.”)

    When the hoax shakes out it will be way too late to bring the public into the cause of combatting global warming. The hoax will poison the water for real solutions.

  42. 342

    Re my last, I meant to say “– a reserve capacity of something better to tap –“

  43. 343
    John Millett says:

    #326
    Patrick, your 255K average temperature of the imaginary atmosphere-free planet is a derivative of energy flux which is the reverse of the Stefan-Boltzmann formulation. Dr Smith’s “Proof of the Atmospheric Greenhouse Effect” (see WIKI – a rebuttal of Gerlich and Tscheuschner)corrects this fault and arrives at 144K average. The “greenhouse effect” is thus (288-144=144)K or an unbelievable 36% of the power of the sun.

  44. 344
    John Millett says:

    #331
    dhogaza, a number of posts that didn’t get by the moderator would have clarified matters considerably. One lists 8 areas in which, for me, the AGW hypothesis does a poor job of explaining climate change and why, in my opinion, there is continuing interest in GCR. Another one demonstrated how internal inconsistency between the general fromulation of the AGW hypothesis and the energy budget effectively rendered the hypothesis moot. [edit]

    [Response: They are moderated because they are nonsense. Stick to specific issues that you are actually interested in, not tiresome generalities that have been debunked hundreds of times. Discussion of theories that posit that the greenhouse effect violates the laws of thermodynamics are OT and will remain so. -gavin]

  45. 345
    John Millett says:

    #332
    Patrick, a shorter explanation. The atmosphere is mostly void (we know this if only because of the 200+ atmospheres needed in liquefying air). Of the 1.5% of atmospheric volume occupied by matter, absorbent matter (greenhouse gases) accounts for 1%. That is greenhouse gases exist in the atmosphere at 150ppmv. Assuming 0.9 absorbance efficiency, overall atmospheric opacity would be 0.000135 cm2g-1. A simple average of atmospheric density at 5km intervals over 15km is 0.00064 gcm-3. This atmosphere would absorb 12% of radiation from the surface, a much lower figure than the AGW energy budget’s 90%.

  46. 346

    Millet, do you have even a grain of intelligence? :)

    Smith‘s 144K is the average temperature for an idealized non-rotating planet with the dark side at absolute zero, and is one of several intermediate steps before he gets close to a real planet. How is this relevant to calculating the greenhouse effect for our very real planet?

    Besides, this is totally OT unless you are trying to illustrate by example how some are so in denial of reality as to pursue irrelevant arguments when the main point is lost. (A good answer to Rasmus’s original question.)

  47. 347
    Patrick 027 says:

    John Millet-

    I recall skimming over Dr. Smith’s writing – it looks very good; I only didn’t read it more closely because I already understand the concept.

    But I don’t remember specifically what situation results in the 144 K average. Is it the situation where the Earth rotates once a year, keeping the same side facing the sun, and without any horizontal heat flow? Or is it with rotation and setting aside diurnal temperature cycles and any longitudinal variations in albedo, so that temperature varies only with latitude – and also assuming no heat transport from north-to-south, and perhaps assuming zero tilt (permanent equinox configuration)?

    I already mentioned that temperature variation causes increased LW emission for the same average temperature, so horizontal and temporal temperature variations over the surface of the Earth will allow the average temperature to be below, perhaps much below, 255 K, and still be in radiative equilibrium in the global time average with absorbed solar radiation.

    But I also mentioned that for the actual temperature variations found over the surface of the earth, I was able to estimate that the actual difference in the equilibrium average temperature is around 1 K. It was a rough estimate (numerical integration over latitude bands and taking an average of two extreme seasons with the annual average, with some experimenting with likely diurnal variation (which really is only significant on land) to see how much that could do), so it might be a little different, but still around 1 K. That would allow the surface to be 254 K or around there. Not 144 K.

    Or do you mean that it would be 144 K without the greenhouse effect and with an albedo feedback in response to the removal of the greenhouse effect? Well, it depends on what the resulting albedo is – I recall coming up with something near 220 K for an albedo increase from 0.3 to 0.6, but that’s just from memory…

    Now, if you include the effect that the surface is not actually a perfect blackbody, you can actually get a temperature that is somewhat warmer than 255 K. If the surface had an emissivity (at all significant LW wavelengths) of 0.96, then the equilibrium temperture T could be found from:

    (255 K/T)^4 = 0.96.

    (T/ 255 K)^4 ~= 1.04

    T/255 K ~= 1.01

    So that’s roughly a difference of 2.6 K, give or take a little.

    —-
    Now, with an atmosphere, the surface also reflects some of the backradiation from the atmosphere; if the LW albedo is isotropic as well as wavelength independent (within the LW part of the spectrum), then the LW albedo would be 0.04 for a LW emissivity of 0.96, thus if the backradiation is 324 W/m2 and the surface LW emission (at 288 K) would be 390 W/m2 for a perfect blackbody, then the actual surface emission with emissivity 0.96 would be:

    (setting significant figure limitations aside):

    390 W/m2 – (390 W/m2 * 0.04) = (390 – 15.6) W/m2 = 374.4 W/m2

    While the reflected backradiation would be

    0.04 * 324 W/m2 = 12.96 W/m2

    So the upward LW radiation, emitted and reflected, from the surface would be (374.4 + 12.96) W/m2 = 387.36 W/m2, which is only 2.64 W/m2 less than what it would be if the surface emissivity were 1.

    And the effect on the radiation going to space, given that 40/390 of the radiation coming up from the surface (assuming both emitted radiation and reflected backscattered radiation is isotropic, as perfect blackbody radiation would be) is 4/39 * 2.64 W/m2 ~= 0.3 W/m2. If the radiation coming from the surface is not isotropic, the result would be a bit different. If the LW albedo increases for radiation at large angles from vertical, then a larger portion of the emitted radiation from the surface will reach space, but a smaller portion of the radiation reflected from the surface will reach space, although the reflected amount will generally be larger because the backradiation intensity is generally larger at larger angles from vertical. IF the LW albedo is wavelength dependent, then it gets more complex. But accounting for the surface emissivity being less than 1 is a relatively small adjustment, and it’s effect on forcings and climate sensitivity would also be small in proportion to those things. The one exception might be a feedback or forcing involving a change in the surface LW albedo, but the effect on tropopause level radiant fluxes will be muted, and I’m unaware of any way for such a LW surface albedo forcing or feedback to be sizable, at least on the global scale, at least in the context of AGW (From Hartmann, “Global Physical Climatology”, 1994, pp. 91 – 92, most land surfaces have a LW emissivity of about 0.90 – including deserts, grasslands, and forests, so ecological shifts wouldn’t do much; water has an emissivity of 0.92 to 0.96 (surface roughness, which is affected by wind, will have an effect), ice is 0.96, fresh snow ranges from 0.82 to 0.995; If 17 % of the land (5 % of the globe) (far beyond what AGW is expected to do) were submerged by water, this could be up to change in LW albedo of 0.06 * 0.05 = 0.003; 390 W/m2 – 324 W/m2 = 66 W/m2, 0.003 * 66 W/m2 = 0.198 W/2 ~= 0.2 W/m2, so depending on the spatial-temporal and angular and wavelength distribution, such a change could increase net upward LW flux from the surface by 0.2 W/m2, give or take, and the effect at the tropopause would have to be less than what it is at the surface. For a warming of 3 K, The water vapor feedback would have a much, much larger effect on the net surface radiative flux, and the effect of regional changes in evapotranspiration might also be larger; the tropopause-level (with equilibrated stratosphere) radiative forcing from doubling CO2 is somewhere around 3.7 W/m2).

    If not that, then what are you talking about? What ‘fault’ are your refering to?

    (If by “derivative”, you mean that the formula for equilibrium temperature for wavelength-independent emissivity, Teq = (absorbed radiant flux per unit area/(Stefan-Boltzmann constant * emissivity))^(1/4), was derived from the formula for blackbody radiant flux per unit area, radiant flux of blackbody = Stefan-Boltzmann constant * T^4, then I don’t see where the fault lies. If by “derivative”, you mean that the 255 K figure was found by taking the derivative of one of the equations just mentioned with respect to temperature or with respect to radiant flux per unit area, then you’re wrong.)

    And what would be unbelievable about something (without knowing what that thing is) being 36 % of the power of the sun. The sun itself is 100 % of the power of the sun. The outgoing LW radiation at the top of the atmosphere is about the same as the solar radiation absorbed by the atmosphere and surface.

  48. 348
    Patrick 027 says:

    John Millet –
    “Patrick, a shorter explanation.”

    Beware of double counting. It doesn’t make sense to multiply the chance of rain tomorrow by the chance of rain tomorrow to find the change of rain tomorrow. It doen’s make sense to multiply the probability of the evolution of horses by the probability of the evolution of horses … etc.

    Patrick, a shorter explanation.

    “The atmosphere is mostly void (we know this if only because of the 200+ atmospheres needed in liquefying air).”

    So what? It is what it is.

    “Of the 1.5% of atmospheric volume occupied by matter,”

    I would have thought it was closer to 0.2 %, and that’s not even including that most of the atom is devoid of matter – but what does that even mean, considering the space-filling distribution of electron orbitals?

    “absorbent matter (greenhouse gases) accounts for 1%.”

    (PS don’t forget clouds – though the condensed water phase is actually a very small fraction either by volume or mass.)

    Roughly true – it will be a little different if we go by mass fraction or by molar fraction, but that’s in the ballpark.

    “That is greenhouse gases exist in the atmosphere at 150ppmv.”

    I’ll let it be for the sake of being entertained that you are using ppmv as the density of a substance relative to what it would be if it filled the space with about 66.7 times the ___ that the atmosphere actually has.

    Assuming 0.9 absorbance efficiency, overall atmospheric opacity would be 0.000135 cm2g-1.

    0.9 what? Since this is unitless, I’ll assume you mean the absorbance over the thickness of the atmosphere. Which pretty much answers the question, doesn’t it.

    But I’m just slightly interested in where 0.000134 cm2/g comes from. By the way, you’ve got the right kind of units, there – area per unit amount of substance. Bare in mind that this comes from effective cross-section areas of molecules/particles, and that they are generally arranged at random in space over a sufficiently small macroscopic volume that it can be approximated as being at constant pressure, etc. This means that over any given infinitesimal distance, those cross sections will block a fraction of the unit area equal to the density times the unit area times the distance. But with each additional distance, the additional cross sections start to overlap. So that the fraction of transmission declines exponentially, not linearly. See Beer’s Law: transmission = exp[- distance * density of extinction cross sections]. The derivative is d(transmission)/d(distance) = – density of extinction cross sections * transmission up to that point. Distance * extinction cross section density = optical thickness = optical depth = extinction cross section per unit area; extinction cross section = absorption cross section + scattering cross section.

    The atmospheric mass is about 10,000 kg/m2. 1 % of that is 100,000 g/m2. 0.000135 cm2/g * 100,000 g/m2 = 13.5 cm2/m2 = 0.00135; the optical thickness over a vertical path through the atmosphere would be 0.00135 if 1 % of the mass had an extinction cross section per unit mass of 0.000135 cm2/g, or 0.135 if all of the mass of the atmosphere had that extinction cross section per unit mass. For small optical thicknesses, transmission decays approximately linearly, so the later figure implies transmission near 87 %, or a bit more.

    “A simple average of atmospheric density at 5km intervals over 15km is 0.00064 gcm-3.”

    Let’s see; most of the atmosphere (close to 90 %) is below 15 km. 0.00064 g/cm3 = 640 g/m3 = 0.64 kg/m3, 0.64 kg/m3 * 15 km = 9600 kg/m2. Okay, that’s roughly correct.

    “This atmosphere would absorb 12% of radiation from the surface, a much lower figure than the AGW energy budget’s 90%.””

    12 % absorption over 15 km is correct for absorption cross section per unit mass of atmosphere of 0.000135 cm2/g.

    ******BUT******

    1.
    Blackbody radiation is isotropic – it is emitted in all directions. While not a perfect blackbody, the surface can’t come anywhere near close to being almost a blackbody without emitting photons over a wide range of directions. For any given angle from vertical, some fraction of photons will be at that angle or farther from vertical than that angle, and those photons will have to go through a path longer than 15 km to get 15 km above the surface, and a higher fraction of those will be absorbed.

    2.
    You never showed how you got 0.000135 cm2/g from ‘absorbance efficiency’ of 0.9; furthermore, whered did you get ‘absorbance efficiency’ of 0.9 from? If you took it from the absorbtion of LW radiation from the surface by the atmosphere, do you not realize that this is the absorption of surface radiation by the atmosphere, given the atmosphere’s density, mass, and composition?

    3.
    Considering how absorption and blackbody radiant intensity vary over wavelength, as well as the directional dependence, there is no single absorption cross section per unit substance that applies to all necessary calculations. There are some wavelengths at which, in the absence of clouds or relatively high humidity, the atmosphere is signicantly transparent, while at other wavelengths it is extremely opaque.

    4.
    Consider a cloud with droplets of 10 micron diameter, with a droplet density of 1 per mm3; this is a density of liquid water of 4 g per cubic meter. A 500 m thick cloud of such density would have a vertical mass path of 0.2 kg/m2. Do you think you could easily see through such a cloud? Now, cloud droplets will affect LW radiation differently than solar radiation (absorption instead of scattering being dominant, and the cross section per unit mass would probably be less, I think), but I’m pretty sure you’d still have trouble seeing through it at 10 micron wavelength or … In fact, satellite imagery of clouds at night use the infrared opacity of clouds to detect them.

    Consider a sheet of aluminum foil. How thick is it? Can you see through it? Granted, condensed matter generally has different properties than gases, but still… Maybe consider some molecules dispersed in a liquid, like food coloring dyes in water.

    Consider the blue light of a clear sky. Why doesn’t the sky look black?

    Look at one of your hairs. How thick is it? If you took a bunch of strands of hair and simply laid them next to each other, without overlapping them, how well do you think you could see through them?

    Maybe you’ve never seen a gas that’s not obviously somewhat opaque at visible wavelengths. I’ve heard that chlorine looks green.

    My point is that small amounts of mass can be significantly opaque.

    You can’t actually see with your own eyes that some atmospheric gases and clouds have significant opacity at LW wavelengths. But we have scientific instruments. We have satellite imagery. We know the atmosphere absorbs a lot of radiation. We can also test gases in labs under controlled conditions. These things have been meausured. There is no data-theory mismatch with these basic atmospheric radiative processes. Look at water vapor imagery. Look at satellite IR cloud imagery. Look at the spectrum of outgoing LW radiation from the Earth (and remember that a majority of the radiation that reaches space is emitted from within the troposphere; so 100 % absorption of surface radiation doesn’t mean zero LW radiation to space – but even the nonzero LW radiation observed can’t be explained without the atmospheric optical properties as they are, given the temperature distribution, and also, we can measure the backradiation from the atmosphere, which can’t be what it is without the atmospheric opacity being as high as it is, etc.).

  49. 349
    Patrick 027 says:

    In light of what I’ve just contributed, could anyone point me to a derivation of the Rossby wave phase speed on a PV front? (It isn’t completely OT because Rossby waves and PV fronts are related to jet streams and barotropic and baroclinic instability and the eddy fluxes of heat and momentum and the tendency of midlatitude storms to lose their tilt with height and decay as equivalent barotropic systems and the momentum fluxes in the stratosphere and NAM and SAM etc. which is related to the shift in midlatitude storm tracks that are expected with global warming as well as ozone depletion, and also occur with volcanic aerosol forcing and I’m not sure how solar forcing would affect it via stratospheric-tropospheric interactions – I’m curious.)

  50. 350
    Patrick 027 says:

    “So what? It is what it is.”

    It’s here. It’s atmosphere. Get used to it. :)!