RealClimate logo

Aerosols, Chemistry and Climate

Filed under: — gavin @ 12 July 2008

Everyone can probably agree that the climate system is complex. Not only do the vagaries of weather patterns and ocean currents make it hard to see climate changes, but the variability in what are often termed the Earth System components complicates the picture enormously. These components – specifically aerosols (particulates in the air – dust, soot, sulphates, nitrates, pollen etc.) and atmospheric chemistry (ozone, methane) – are both affected by climate and affect climate, since aerosols and ozone can interact, absorb, reflect or scatter solar and thermal radiation. This makes for a rich research environment, but can befuddle the unwary.

I occasionally marvel at the amount of nonsense that is written about climate change in the more excitable parts of the web, and most of the time, I don’t bother to comment. But in relation to the issue of aerosols, chemistry and climate, I read yesterday (h/t Atmoz) probably the most boneheaded article that I have seen in ages (and that’s saying a lot).

The hook for this piece of foolishness were two interesting articles published this week by Ruckstuhl and colleagues and a draft EPA report on the impacts of climate on air quality. First, Ruckstuhl et al found that as aerosols have decreased in Europe over the last few decades (as a result of environmental standards legislation), the amount of solar radiation at the ground has increased while the amount reflected to space has decreased. They hypothesize that this may have helped Europe warm faster in the last few decades than it would have otherwise done. Or equivalently, since the aerosols are anthropogenic, that European temperatures had been subdued due to the cooling effects of the aerosols – and since they are now decreasing, the full effects of the greenhouse gases are starting to be felt. This is just an update to the ‘global brightening‘ story we have touched on before. The EPA report is concerned with the impacts that climate change can have on atmospheric chemistry, and in particular the summertime peaks in urban ground-level ozone which are a well-known and serious health hazard. These are affected by local temperatures, cloudiness, temperature sensitive biogenic emissions and patterns of weather variability. Again, it is a story we have discussed before.

But the NewsBusters article succeeded in getting almost every aspect of these stories wrong. How do I correct thee? Let me count the ways.

  1. Aerosols are not smog:

    First they confuse aerosols with photochemical smog. Both are pollutants, but the first is dominated by sulphate emissions from coal burning power plants, the second from ozone precursors such as NOx, volatile organic compounds, and carbon monoxide mainly emitted from vehicles. (Note that ozone is not directly emitted, but is created by chemical reactions from the precursors with the addition of a bit of photolysis – i.e. sunlight-driven chemistry). The effects on climate are very different: ozone is a greenhouse gas, so increases cause a warming, while sulphate aerosols are reflective, and so increases cause a cooling. The air quality issues in the EPA are almost all focused on ozone.

  2. Europe is not the Globe:

    The next error is to equate changes in temperatures in Europe to the globe. While it would be true that if global aerosol levels declined it would lead to increased global warming, aerosol trends in Asia are increasing strongly, even while those in the US and Europe are dropping. The net effect is possibly a slight drop, but the impact on global temperature is as yet unclear. This regionality matters in both the sulphates case and for ozone. The relevant chemistry is sensitive to water vapour and temperature in varying ways as a function of the pollution level. In remote ocean areas, surface ozone will likely decrease as the globe warms for instance (due to increasing water vapour). In polluted environments increased temperatures and larger temperature-sensitive emissions of isoprene cause enhanced ozone levels.

  3. Surface ozone is not in the stratosphere:

    Next, NewsBusters asserts that the ozone story is confusing because of the

    .. treaty called the Montreal Protocol. This was designed to reduce and eventually eliminate the production and release of a number of substances thought at the time to be depleting ozone.

    Ummm…. those substances (chiefly chlorofluorocarbons – CFCs) are still thought to be depleting the ozone layer – which is in the stratosphere, some 30km above the ground-level ozone that people shouldn’t be breathing. CFCs have no impact on ground-level ozone at all (since their reactive chlorine is only released in the stratosphere).

  4. The final inanity:

    Wouldn’t it be fascinating if such efforts [such as the Montreal Protocol] lead to cleaner air around the world which ended up warming the planet, and that additional warmth is now breaking down the very ozone we thought we could save?

    Every part of this sentence is wrong. The Montreal Protocol had no impact on cleaning the air, it stopped the growth of CFCs which are powerful greenhouse gases (in addition to their role in depleting stratospheric ozone), therefore it slowed global warming, rather than increasing it, and we aren’t trying to save ground-level ozone. Had any of this been true it would indeed have been fascinating.

What should we make of this? Unfortunately one must conclude that no mistake is too dumb for someone, somewhere to make if they think they can spin it into supporting their anti-science agenda. For them complexity is something to be abused rather than a challenge to be understood, underlining quite clearly (again) the difference between science and propaganda.

356 Responses to “Aerosols, Chemistry and Climate”

  1. 251
    Poptech says:

    The title of the Reuters story clearly states:

    “Study links global warming to more smog

    And includes this statement:

    “U.S. environmental regulators quietly published a draft study on Thursday that linked global warming to higher levels of smog that could harm human health.”

    This is the story Mr. Sheppard links to. It is the fault of the editor of Reuters for not using the word “Photochemical Smog” if this is what the EPA report states. The word usage of smog, as I have proven, can easily be defined in different ways, including the context in which Mr. Sheppard used the word.

    Your claims of him equating the word Aerosols for Smog are unfounded. No where does he use these words interchangeably. At best he implied that Smog can be composed of Aerosols which fits under the definition of the word Smog as I have proven.

    Your claims of him equating Aerosols to ‘Photochemical’ Smog are ridiculous. His usage was based on the unclear context of how the word Smog was used in the Reuters piece. Anyone reading his piece can clearly see he never used or implied ‘Photochemical’.

    You may find semantics boring but misdefining an authors context (even if it was based on a poorly worded Reuters piece) is disingenous.

    [Response: My point in the above piece was that Sheppard didn’t know what he was talking about, and yet saw fit to pontificate at great length on the perfidy of scientists. Your responses here underlines that in spades. I suggest that when Sheppard reads a word that he doesn’t understand in a press report, he look up the underlying study to see what they are talking about (has he even read the EPA report yet?). I think this is part of that new-fangled concept called ‘journalism’ (he might want to look that up too). – gavin]

    [Response: One further point, how could you read even the part of the Reuters article he quoted and not know that it was talking about ozone? – please, your efforts to dig Sheppard out of a hole are getting embarrassing. – gavin]

  2. 252
    Rod B says:

    Guenter, Mark’s 223 answer is better than mine…

  3. 253
    Lawrence McLean says:

    Clear Thinker,
    From a geothermal point of view the earth is cooling down. 700 million years ago the earths volcanism was far more active than now. In spite of that, changes in the atmosphere resulted in the snow ball earth. It was volcanic releases of CO2 that caused the thawing, not the direct heat.

    In addition to clear thinking, a person should also observe clearly. That means observing objective reality without filtering it through your preconceptions and prejudices.

    Here in rural Australia, among the farming community you will not find many people who dismiss Global Warming. It is absolutely in your face. I have noticed many denialists making out that global warming has slowed down these last 10 years. Rubbish! Check out:

    Have you heard the expression regarding telling your grandmother to suck eggs? Your questions to Gavin Schmidt fall deep into that territory.

    The credibility and honesty of the climate scientists as represented by the contributors to this site are rock solid.

    I had a brief look at the newsbusters site. The level of arrogance and ignorance is at extreme levels. It is full of people who think that all the knowledge that they know, is all the knowledge that there is. In other words smartasses!

  4. 254
    Rod B says:

    Hank (228), no, I was making a simple comparison of the miniscle undersea and other heat sources that was asked about.

  5. 255
    Rod B says:

    Martin (248), thanks for the info. I had seen in an article that I was just skimming that the probability of translation to vibration transfer is less than the other way, not the same. It now occurs to me (and I’m asking for reaffirmation of your point) it might not have been referring to the mathematical thermodynamic probabilities, but to them looking different because of the lower population of higher translation energy molecules.

  6. 256
    Hank Roberts says:

    Thanks Rod.

    On the two articles being discussed in the first post, Gavin’s right to remind us to, well, read them first. It’s hard to be confused about the content after reading them even once, seems to me.

    Y’all notice the title of the file at the bottom of the ‘Assessment’ draft page? “… Impacts on O3”

  7. 257

    Dear Poptech,

    Dr. Schmidt has been incredibly patient with you, but it is quite clear to any reasonable reader who is confused and who is not. Please stop quibbling and putting up bogus “debater’s points.” Do you realize how bad you are making “your side” of the debate look?

    Please, give it a rest.

  8. 258
    Ray Ladbury says:

    Poptech, The fact is that you were incontrovertibly WRONG in your assessment of the research. Now given that fact, the question is what is the slope of your learning curve. To contend that you were not wrong is simply indefensible. Sheppard made some ignorant assumptions and drew absurd conclusions–and then projected that absurdity to the climate science community. YOU accepted Sheppard’s conclusions carte blanche. To contend that it was not your fault that you were wrong is irresponsible and does not benefit you (learning slope zero). Rather perhaps you should look at why you were wrong–lack of background knowledge, blind acceptance of conclusions from unreliable sources, failure to check those conclusions via trusted sources (original research, independent experts, etc.). These all suggest ways you can avoid being wrong in the future. Finally, if you really want your learning curve to steepen, ask yourself whether these same failures might also lead you astray in other areas (e.g. climate science). Live and learn or just live–the choice is yours.

  9. 259
    Martin Vermeer says:

    Rod #255: precisely so.

  10. 260
    Guenter Hess says:

    Martin, Mark, Rod and Ray,
    Thanks for the discussion. I would like to keep on going because I learn from you and this is good.
    I have still problems with the assumption used because of the following topics:
    1. The quantum yield for infrared spectroscopy at atmospheric pressure is usually well below one and quantum yield is defined as number of emitted photons divided by number of absorbed photons. This is caused by deexcitation due to collisions. This in turn suggests that the relation between emission and absorption is also well below 1 and not 1 as Kirchhoff’s law suggests.
    2. If you consider a model or system containing 3 subsystems that are in steady state condition, a solid body at 300 K, a slab of atmosphere on top with 295K and another slab of atmosphere on top with 290 K. The three subsystems are of course not in thermal or thermodynamic equilibrium, but at most only in local thermodynamic equilibrium. Therefore the principle of detailed balance is not strictly required.
    3. The average translation energy of a molecule at 300K is about 5E-21 Joule. The vibrational energy of the CO2 bending mode at 15 µm is 1.3E-20 joule. Therefore the excitation of the vibrational mode of CO2 by collision with a nitrogen molecule in the ground state has at best a low probability.

  11. 261
    Hank Roberts says:

    > It is the fault of the editor of Reuters

    And we are shocked, _shocked_ to find we can’t rely on what we read in the newspapers eh?

    We all have to face this sometime in our lives, usually the first time we read in a newspaper about something we actually know first hand and realize:

    “Wow, they got that wrong; gee, what about everything else I read? Maybe I better check for myself.”

    “.. fool me once, shame on — shame on you.
    Fool me — you can’t get fooled again.”

  12. 262
    Martin Vermeer says:

    Guenter Hess writes #260:

    1. The quantum yield for infrared spectroscopy at atmospheric pressure is usually well below one and quantum yield is defined as number of emitted photons divided by number of absorbed photons. This is caused by deexcitation due to collisions. This in turn suggests that the relation between emission and absorption is also well below 1 and not 1 as Kirchhoff’s law suggests.

    Don’t know IR spectroscopy at all… but don’t you use a laser? They have huge brightness temperatures, thousands of degs, way more than your sample. Then the absorbtivity relates to the laser brightness, and emissivity to the sample’s Planck brightness. Apples and oranges.

    If it’s a pulsed laser (is it?) you don’t even have necessarily LTE.

    2. If you consider a model or system containing 3 subsystems that are in steady state condition, a solid body at 300 K, a slab of atmosphere on top with 295K and another slab of atmosphere on top with 290 K. The three subsystems are of course not in thermal or thermodynamic equilibrium, but at most only in local thermodynamic equilibrium. Therefore the principle of detailed balance is not strictly required.


    3. The average translation energy of a molecule at 300K is about 5E-21 Joule. The vibrational energy of the CO2 bending mode at 15 µm is 1.3E-20 joule. Therefore the excitation of the vibrational mode of CO2 by collision with a nitrogen molecule in the ground state has at best a low probability.

    Yes. Compute it as follows: the population is reduced by a factor

    (2/3)*exp(13/5) = 0.049 (look familiar?),

    where 13/5 is the energy level relative to mean energy kT for that temperature, 2 the vibrational, 3 the translational degs of freedom.

    I may misremember the details though, physics class was long ago ;-)

  13. 263
    Clear Thinker says:

    It’s funny how just as I was about to ask a question, someone provides an answer. I wish I could patent that ability.

    When Mr. Schmidt gave me the following answer “Precip ~ 3mm/day globally w/ about -1 W/m2 surface energy flux” I immediately copied and put into the Google search bar. For the most part Google laughed at it, but I did learn from the experience. Thanks to Mr. Levenson in #250 my suspicions were confirmed. It’s not that I was looking for Mr. Schmidts answer in my search, I was looking for the info that backs up his answer. More precisely I was looking for how the measurements were collected so he could make his suggestion that about 3mm of precip / day over the entire surface of the earth. Lo and behold, I could not find them. My thanks goes to Mr. Levenson for admitting that these came from ‘estimates’.

    I do not have a lifetime left to me in order to research every single detail that comes up in arguments between the science believers and science non-believers and I am not steeped in the mathematics involved that both sides are using. With this in mind, when I ask a question, could some understanding soul please send some Cliffs Notes to concerning the subject of discussion. I will continue to consider any and all answers here for education’s sake, but the Notes would be helpful.

    Thanks to all.

    [Response: Everything is an ‘estimate’, but global precipitation has been reasonably ‘estimated’ by satellites and stations blends for years. Google ‘CMAP’ or ‘GPCP’ instead. Their global totals are slightly on the low side since they don’t detect snow very well and come in at just under 3mm/day. Don’t think that just because *you* can’t google something it means it doesn’t exist. – gavin]

  14. 264
    Hank Roberts says:

    Mr. Clear, you can learn to search. (Note in “Questions The Smart Way” the advice about asking for help by email. I do recommend Eric Raymond’s advice.)

    1) expand (spell out) the abbreviations
    2) Google uses a minus sign to mean ‘ignore this’
    3) use Scholar
    4) note which words (hilighted) got hits
    5) read a few and refine your search further

    I worked out the above by:
    pasting your exact quote into Scholar;
    fiddling with the search string.
    First tries got nothing, nothing, nothing.

    Then it worked. Then I limited to ‘Recent’
    Precipitation 3mm day globally surface energy flux

    Here it is. You can improve on this from here:

    If this isn’t making sense, your public library’s reference desk is a very good place to ask. Most of the really boring library work is offloaded to computers now and they can really go deep into helping people use the library, and are eager to. Try!

  15. 265
    Mark says:

    “1. The quantum yield for infrared spectroscopy at atmospheric pressure is usually well below one and quantum yield is defined as number of emitted photons divided by number of absorbed photons. This is caused by deexcitation due to collisions. This in turn suggests that the relation between emission and absorption is also well below 1 and not 1 as Kirchhoff’s law suggests.”

    When you apply kirchoff’s law, you apply it when it’s in equilibrium. And in a medium with a spread of energies, the figure cannot mean anything anyway: you can get 10 photons out for 1 photon in if the 10 are at 10% of the energy.

    Rather like a laser, if your CO2 is in a higher excited state it will emit more than 1 photon per photon being absorbed (and remember, these are average figures: you get this because an excited CO2 molecule may give off IR radiation without absorbing photon first).

    What you will get is a spectrum of output photons that doesn’t necessarily match the absorption lines your IR is being captured at. The total energy in and the total energy out are the same. The number of photons making it up isn’t 1:1.

    (this is a little confused because the input window is kind of small and I’ve just finished dinner and the brain is being put on standby why the digestion system takes over).

  16. 266
    Mark says:

    PS Guenter, we don’t have a laser on the earth re-radiating. Your concentration on that is somewhat silly. The earth radiates a broad spectrum and the 15um wavelength isn’t a big part of the power losses of the warm earth.

  17. 267
    Guenter Hess says:

    I just tried to find measurements or quantitative correlations about the relation between absorption coefficient and emission coefficient in the frequency region of the CO2 absorption lines at atmospheric pressure to test the assumption that both are equal.
    And the notion about quantum yield for infrared emission spectroscopy is what I found in my spectroscopy book by Wolfgang Demtroeder. Infrared emission spectroscopy is also part of remote sensing in atmospheric sciences. I might miss something and it might be wrong , but I don’t think it is somewhat silly.

  18. 268
    Guenter Hess says:

    I think I found in the literature (Radiative Transfer in the Atmosphere and Ocean by Thomas and stamens) an important difference that slipped past my attention. There is a difference between the relation of absorption and emission for surfaces and for volume emission.
    1. For surfaces : absorptance equals emittance
    2. For volume emission of planetary media: volume emittance is proportional to the absorption coefficient
    So I think I am somewhat reconciled. Thanks for your input.

  19. 269
    Clear Thinker says:

    Wait a minute Mr. Schmidt, one of the first things I looked at was satellites. In fact, I found at one of the NASA sites that there are no satellites that at the present time can measure precip. And if I understood correctly, especially over Oceans. We seem to be almost 5 years from being able to use sats for these measurements.

    [Response: Not so. – gavin]

    Are the stations you speak of all land based?

    On the surface the comment about ‘everything is an estimate’ seems benign, but your other comment “but I don’t see you querying gravity, the heliocentric model, the big bang etc.” suggests that you consider these issue are absolutes and no longer beyond question. But you don’t hear science saying “we estimate them to be absolutes”. My point is, we still do not have all the, dare I say, ‘solid data’, to say that mankind is responsible for the cooling or the warming of the earth. And there are ten’s of thousands of scientists that agree.

    Here’s a question I was asked one time… If earth as we know it is destroyed by mankind due to AGW and mankind as a species is eliminated, will the earth recover without us?

    [Response: Sure – it took about 5 miilion years to recover the biodiversity lost after the KT impact. I imagine the Earth is still that resilient. Not quite sure who cares though. – gavin]

    My thanks goes out to Mr. Roberts for honestly trying to help without disparaging remarks involved. FYI… I use scholar all the time and your suggestion is a good one. Starting there and drilling down usually works well. My comment about Google was mostly tongue in cheek.

    Thank you for your continued patience.

  20. 270
    Rod B says:

    Guenter (260), I make a stab and trust the others will keep me honest. Kirchoff’s Law says the absorptivity equals emissivity. It does not say that absorption (always) equals emission. It would only do that over time in a perfect LTE environment. For example the sun’s actual emitted energy far exceeds its absorbed energy.

    I have the same head scratching over the translation to vibration transfer given the different energy levels. Though the difference would not make the transfer impossible, just “unlikely” But unlikely applied to 10^26 or so molecules, e.g., is still a pile of molecules.

  21. 271
    Marcus says:

    Clear Thinker: #269: No, climate change isn’t “perfectly” understood, and neither are gravity, the big bang, or any other scientific theory. But the point is not whether we understand it perfectly, but whether we understand it sufficiently well to begin to make policy based on the science.

    And I think the answer to that is a resounding yes. Decisions are made under uncertainty all the time, in a multitude of cases where there is a lot more uncertainty than in AGW. But in this one specific area, the Sheppards of the world seem to require an absolute certainty before any action is taken.

    And the vast majority of the scientific experts in the area are in general agreement that the understanding of climate change is sufficient such that policymakers can move ahead and do their thing. Yes, there are some dissenters, as there are in any field: heck, I remember this one scientist who would show up at chemistry and physics lectures at Caltech, and would walk up to the lecturer afterwards to ask them “and given that my recent research has showed that quantum theory is ungrounded, how would your interpretations of these results change?” The difference being that there isn’t a giant movement to take the occasional wacko PhD who disbelieves quantum and spread their every poorly researched thought piece across the internet…

  22. 272
    Poptech says:

    I am sorry Gavin my posts are to explain the context in which Mr. Sheppard used the words you accuses him of misusing based on simply reading his piece. You have failed to prove Mr. Sheppard does not understand the meaning of any words since the words you accuse him of not understanding do not appear in his piece ie: ‘Photochemical’. The context in which he used the word Smog fits in with the defined definition.

    The Reuters piece used the word Smog twice in a general context, those are the facts. If the EPA piece spoke of only Photochemical Smog then Reuters should of never used the word smog in a general context. That Reuters later start talking about Ozone Smog does not change the fact that it is not clear the EPA piece is only speaking of Ozone smog from that news release.

    Kevin, the only ones confused are Gavin and some of the commentators here. I have proven the what the definition of the word Smog means, and defended it’s context based on the general wording of the Reuters piece.

    Ray, I was not wrong in any assessment of any research because I never assessed these pieces. The only failures I see is in Reuters poorly wording a news release. It seems that lying about what others say is a common with the commentators here. It is clear that the administration here has no problem allowing personal attacks on others but censors any defense of these accusations. My learning curve is fine, it is your reading comprehension which is not. In Gavin’s quest to attack all those who disagree with him he fabricated words and invented contexts which were not used by Mr. Sheppard and implied a direct ignorance on Mr. Sheppard of what ‘Photochemical’ means. These sort of allegations are childish and do not speak well of the supposed scientific community here. No where in Mr. Sheppard’s piece does he use or imply that the word Aerosols is the same as the word Smog or that he does not understand what Photochemical Smog is. That is the reality.

    Defending against fabricated word usage hardly makes me or anyone look bad.

    [Response: Now you are making things up. I have never insinuated that Sheppard didn’t know what photochemical means. I have merely pointed out that he doesn’t understand the differences between ozone and aerosols, or tropospheric and stratospheric ozone. And now you are blaming Reuters for you and Sheppard’s inability to read more than two lines in to an article…. You don’t appear to realise that this is no excuse at all. Try taking some responsibility here – you and Noel messed up because you didn’t read the slightly-smaller print. Next time, try doing some research. – gavin]

  23. 273
    David B. Benson says:

    Marcus (271) — Back then there wasn’t an internet for the wackops to use to disinform…

  24. 274
    Joel Black says:

    Mr. Schmidt,
    At many points in this thread there are recitations of what is known about AGW and CO2 forcings. In order to avoid belaboring issues that have been sufficiently discussed, could you please point out to me areas of your research into these issues where the understanding is not sufficiently complete in the climatological community. I’m interested in following the latest research, not re-hashes of settled issues. As you can imagine, it is hard for a layman to separate the wheat from the chaff.
    Thank you.

    [Response: There’s lots of stuff that people worry about – and there is some overlap with the what gets attention in the media. The difference is that most scientists realise that some new knowledge about aerosols or clouds or paleoclimate or ocean variability doesn’t automatically mean that global warming is a scam. Each of those fields have huge and relevant issues – how predictable are the statistics of ENSO, what is the impact of forcing on regional rainfall, can we ever get a handle on cloud-aerosol interactions etc. Personally, I’ve been focusing on how to bring paleo-climate studies into the orbit of the models so that we can use them to test models ‘out-of-sample’ – lots still to do there. – gavin]

  25. 275
    Tank Dobermann says:

    Mr. Clear Thinker(#269), with all due respect, it has become apparent your civility is a ruse, has it not? Please refer back to comments #241 & #246 in referring to Dr. Schmidt. This is not site for political debate. It’s a scientific site to gain an understanding of and appreciation for the scientists who work to inform the world on Climatology. What have you learned in the brief time you’ve been here? Will you be able to help correct the inaccuracies in Noel Sheppard’s reporting? Why is Noel Sheppard personally unable to defend his position on this site? Quite possibly, his enlightenment could start here and progress to a better overall understanding and education of Climatology.

  26. 276
    Poptech says:

    Where did Mr. Sheppard state an improper usage of the word ozone? Did he give an inaccurate explanation of this somewhere in his piece that I missed? Yet you continue to fabricate this.

    How come you keep fabricating that I messed up? How did I mess up? I made no correlation between ozone and aerosols and neither did Mr. Sheppard. Why are you being dishonest?

    Mr. Sheppard admits he did not link to the EPA report and only the Reuters article. That is a separate issue and not what I am addressing. So instead of merely pointing this out you state fabrications about his understanding of ozone and photochemical smog and fabricate things he never said. Based on the Reuter article’s general usage of the word smog allows for what Mr. Sheppard said and based on the widely defined word Smog it allows for his usage. Your argument stops at the actual EPA report says… since Mr. Sheppard never linked to this. That is the reality whether you want to admit it or not.

    I take responsibility for what I actually said and meant (I am sure Mr. Sheppard does the same) not for what you fabricated was said.

    [Response: Now you are getting hysterical. Why not just admit that Sheppard got it all wrong? – gavin]

  27. 277
    Jerry S says:

    “Hank Roberts Says:
    20 July 2008 at 9:08 PM
    Mr. Clear, try the link at the top of the page, “Start Here” — and also try the first link under Science in the sidebar. You’ll find most of the frequently asked questions are answered there, including the one asked by Mr. Sheppard. It’s an intermediate-type question, that will be understood after reading some of the basic ‘Start Here’ FAQ answers.
    Most of us here are like me ordinary readers; we try to point new readers to the basics to avoid retyping the answers where they’re digressions.”

    I have no dog in this show and the hubris shown on both sides or the argument is to say the least entertaining, but if you’re going to send people to read a start here or FAQ, someone should at least update the information (some links don’t work anymore and some are just not accurate anymore) provided so that a “laymen” can actually learn something rather than be force fed the AGW propaganda. I’m sorry but when you go to a link that has the Sierra Clubs’ 10 Ten Things You Can Do To Stop Global Warming and the Pew Centers’ Top 10 Things You Can Do To Fight Global Warming, the site looks less and less like the bastion of pure science that it purports.

    [Response: I checked all the links on the sidebar and on the Start Here page and all seem to be fine. The Sierra Club is not listed. The Pew Center is, but that is because they do a good job. If I missed something, please let me know. – gavin]

    Now I’ve been a lurker and I just haven’t had the necessary energy to read everything and respond but after stumbling along this discussion (and delving into your start here link) I figured it was about time to bite.

    FAQ 1.1, Figure 1. Estimate of the Earth’s annual and global mean energy balance.

    The picture was taken from the following paper should anyone like to read it.

    So my questions are:

    Is the Solar Radiation actually a constant? As far as I know, all climate models assume it to be so. Now what if it isn’t? How much change is required to change the models output? Can the change reflect the noticed warming of the last century, if not why not?

    [Response: No. Incorrect. Quite a lot. No. Not large enough and too flat over the last 50 years. – gavin]

    Is the narrowband Malkmus model which was used to represent the longwave radiation transfer still correct? Is the model applicable to non-homogenous gases?

    [Response: Some answers here and references therein. -gavin]

  28. 278
    tamino says:

    Certain posters have arrived recently, apparently with the goal of stirring up trouble. The result of their efforts is probably best characterized by Gavin’s last line in the “Once more unto the bray” post: The obvious ineptitude of this contribution underlines quite effectively how little debate there is on the fundamentals if this is the best counter-argument that can be offered.

  29. 279
    Clear Thinker says:

    Mr. Dobermann,

    Have I not been civil?

    Have I debated politics?

    Is this site strictly for scientists?

    Have I been defending Mr. Sheppard?

    Sir, you seem to have me confused with someone else.

  30. 280
    Marcus says:

    Poptech: I think the point is that anyone with even a mediocre understanding of the science of climate change would know that a) tropospheric ozone is a pollutant and a GHG, and b) sulfate aerosols are a pollutant and a cooling influence. Once one understands those two facts, then no confusion arises from one study noting warming caused by aerosol reductions, and another study showing increased ozone from global warming.

    Now, Mr. Sheppard is presenting himself publicly as someone who has an understanding of climate change sufficient to determine that the majority of the experts in the field are wrong. However, his post seems to indicate confusion about how the two are related. Now either this demonstrates that Mr. Sheppard does not understand basic elements of climate science (and therefore should perhaps wait until he reads and understands more basic textbooks before making public posts about the subject), or it indicates that Mr. Sheppard is trying to deliberately obfuscate the issue in order to confuse his readers who very well might not have (and should not necessarily be expected to have) a reasonable understanding of climate science.

    And while the Reuters piece does not use the word “photochemical” it does use the term “ozone smog” and “ozone” over and over again. Which should make things pretty clear to both you and Mr. Sheppard, but apparently it does not.

  31. 281
    Hank Roberts says:

    Jerry? Pointer please? What does Google miss that you know?

    +realclimate +”Sierra Club” “Ten Things You Can Do To Stop Global Warming” – did not match any documents.

    I’d guess you clicked out of RC’s page, your focus moved into other sites, and you found links there that didn’t work or led to the Sierra Club. That happens.

    Er, Tank? Eschew. See Gavin’s responses earlier, he’s keeping an admirably high standard of patience in moderation here.

  32. 282
    Hank Roberts says:

    > honestly trying to help without disparaging remarks

    Like the man said: “[… stick around here and see how discussions can actually evolve without people resorting to ad homs. – gavin]”

  33. 283


    I asked you nicely to give it a rest–“please” not once but twice.

    You ask, “where did you mess up?” and claim to have proven something about the definition of smog. I am going to offer a few small instances of “mess ups,” including your masterpiece on the definition of smog, in one last burst of optimism that you do indeed have a nonzero learning curve. After that, I intend to skip every post you write because they are not teaching me anything and have become quite tedious.

    From your post #103

    GS: “Smog, as all the definitions state, is an amorphous mix…”

    You: Actually all the definitions do not state this…

    Definitions follow; asterisks give my emphasis:

    Smog – “a *mixture* of fog and smoke or other airborne pollutants such as exhaust fumes” (Encarta)

    Smog – “fog or haze intensified by smoke or other atmospheric pollutants.” – Compact Oxford English Dictionary
    (I.e., fog or haze *mixed* with pollutants.)

    Smog – “air pollution, especially in cities, that is caused by a *mixture* of smoke, gases and chemicals” – Cambridge Advanced Learner’s Dictionary

    Smog – “a haze caused by the effect of sunlight on foggy air that has been polluted by vehicle exhaust gases and industrial smoke” – Wordsmyth
    (Again, fog *mixed* with pollutants.)

    Smog – “*Mixture* of particulate matter and chemical pollutants in the lower atmosphere, usually over urban areas.” – American Geography Glossary

    Smog – “Originally smog meant a *mixture* of smoke and fog. Now, it means air that has restricted visibility due to pollution.” – NOAA.

    (So, *every* definition does indeed include the idea of mixture, either implicitly or explicitly. As for “amorphous”, that word is defined as “lacking a definite shape or structure,” which accords well with all of the definitional scenarios above. Why do you think, then, that the definitions differ substantially from the “amorphous mixture” description given? My guess is that it is because you are too busy debating to actually try to understand–but that’s only my guess, of course.)

    You: You are correct your post is confusing because it states that Aerosols are not smog but are a pollutant, yet the definition of the word smog allows for it to be defined as composed of Aerosols
    (Stop, this sentence has already outrun its own punctuation.)

    and you then change your mind and claim it is not really pollution.
    (To what does “it” refer? Gavin’s mind? Smog? The definition of the word smog? I can’t really argue with this sentence because it is so badly written that its meaning is quite unclear.)

    This sort of inaccurate information coupled with links to an unreliable source such as Wikipedia makes one question the scientific integrity of this site.
    (Hey, at least the Wiki people can write sentences that make sense, and can even understand dictionary definitions.)

    Someone reading you post would come to believe that smog cannot be composed of Aerosols which is not true.
    (Actually, they wouldn’t–or at least i didn’t and I don’t see why anyone else would, either. The GS post was clear, unlike your efforts.)

    And, by the way, I note you never did answer Gavin’s challenge directly.

  34. 284
    Hank Roberts says:

    > Based on the Reuter article’s general usage …
    > based on the widely defined word …

    See, there’s the mistake. Newspapers aren’t always reliably correct in the details. You have to learn to check for yourself what they claim to be telling you about. On any subject you know, you realize this immediately. When it’s a subject you don’t know, you can get fooled.

    Remember: “fool me once, shame on me …. don’t be fooled again.”

  35. 285
    Chris N says:


    I’ve said for months on this site that optical brightening is the cause of a significant amount of warming since the 1980’s. Of course, the proposal was attacked to no end by your regular contributors. I thought this was clear from looking at the divergence of NH and SH anomalies (since the 1980’s) in the satellite-based dataset (note that 80% of sulfates are generated in the NH). Again, my conclusion seemed pretty logical to me, but apparently most of your readers couldn’t grasp it for one reason or another. I’m glad there is a paper that backs up my hypothesis.

    Also, I thought I told you to take care of yourself (i.e., global temps are likely heading down for the next 10-20 years, thus expect stronger attacks from deniers). Having hissyfits (even if warranted) is not going to do your health any favors. It’s going to be a long 20 years of cooling, so pace yourself.

  36. 286
    Mark says:


    Guenter, you’re welcome. The “silly” comment was the concentration on a specific wavelength as the be-all and end-all of absorption in the atmosphere. It makes thinking about things easier, but it’s only the start of knowing.

  37. 287
    David Donovan says:


    Seems to me you have two choices if you decide to press on.

    1) Admit Mr. Sheppards article is inaccurate (we screwed up sorry will endeavor to do own homework next time).


    2) Continue to stick by your guns and insist that that the article’s authors knew precisely what they were talking about.

    To my mind, choosing 2 directly implies that the authors were deliberately writing a misleading inaccurate article.

    So….It seems to me, that the authors need to admit to either having screwed up or to being liars.

  38. 288
    Ray Ladbury says:

    Poptech, #272, Whatever, dude. Learning slope=0.0 with high precision.

  39. 289
    Jim Galasyn says:

    Chris N, your prediction that scattering from sulphates will dominate global climate is being tested in the Sulphur Cycle Experiment. Why don’t you install the BOINC client and use your spare computer cycles to help support your case.

  40. 290
    Hank Roberts says:

    Tempted to wale away at unresponsive irritations? Eschew.

    ‘I’m gwine ter larn you how ter talk ter ‘spectubble folks ef hit’s de las’ ack,’ sez Brer Rabbit, sezee. ….
    Tar-Baby stay still, en Brer Fox, he lay low.

  41. 291
    Malcolm Kass says:

    I actually don’t really have an issue with this blog post other than your claim that atmospheric chemistry is “complex”. I assure you, atmospheric chemistry is by no means “complex” as compared to issues that a chemical engineers must deal with. Try refracting sour crude, then we will talk.

    And honestly, as this was first time at the blog, I am impressed with the overall level of knowledge of chemistry. Granted, none of you are chemists or chem. engineers, but you have the basics correct.

    [Response: I can’t speak for other chemical systems, but I would point out that the number of possible reaction paths for the formation, say, of secondary organic aerosols from pinenes and turpenes are enormous and, I think I’m correct in saying, most have not be measured in the lab. My (limited) experience of chemistry/aerosol interactions (surface oxidation, mixing states, hydrolysis, deliquesence, accretion, growth etc.) have left me in no doubt that this is complex. But maybe it’s all relative. – gavin]

  42. 292
    Clear Thinker says:

    Chris N,

    Sir, could you point me to the following quote you referenced on post #285… “(i.e., global temps are likely heading down for the next 10-20 years, thus expect stronger attacks from deniers).”

    You don’t hear this much so I’m interested in it.

    Thank you.

  43. 293
    Hank Roberts says:

    Clear, you can find Chris N at that other site; Google may be your friend.

  44. 294
    dhogaza says:

    Classic “Clear Thinker” …

    You don’t hear this much so I’m interested in it.

    The claim’s not made by a climate science researcher so Clear Thinker *immediately* jumps to the conclusion that there must be something in it …

  45. 295
    Poptech says:


    I said ‘state’ as in explicit not implicit. This is the luxury of choosing my own definitions for my words since I wrote them.

    Anyone reading this conversation can clearly see the conflict with Gavin labeling aerosols pollution and then not really.

    Was your comment about the writers of Wikipedia being able to write a correct sentence and define words properly supposed to make me spit my drink onto my desk? If not then your naive understanding of Wikipedia is impressive.

    So please tell me why Gavin stated “Aerosols are not Smog” if not to imply that someone confused these words? He might as well have said any other comparison like “Al Gore is not a Prophet”.

    I have clearly explained the context of the words used by Mr. Sheppards. He has already explained the satrical nature of it, yet I feel no one here understands sarcasm. I am not surprised.

    [Response: Now NewsBusters is sarcasm? Which is supposed to justify any manner of nonsensical statements? Ah…. Sheppard did confuse smog (in this case very clearly referring to ozone) with aerosols, but he was just trying to be funny? Funny peculiar maybe, funny ha-ha? Not so much. – gavin]

  46. 296
    Hank Roberts says:

    20 July 2008 | doi:10.1038/ngeo262

    Increase in hourly precipitation extremes beyond expectations from temperature changes
    Geert Lenderink & Erik van Meijgaard

    Geology, March 2007; v. 35; no. 3; p. 215–218; doi: 10.1130/G23261A.1; 3 figures; Data Repository item 2007048

    Abrupt increase in seasonal extreme precipitation at the
    Paleocene-Eocene boundary

  47. 297
    Jim Galasyn says:

    I get it now, NewsBusters is a parody site! Soon we’ll see Stephen Colbert explaining why global warming is mass hysteria propagated by bears

  48. 298
    Hank Roberts says:

    > I said ’state’ as in explicit not implicit. This is the luxury of
    > choosing my own definitions for my words since I wrote them.

    “When I use a word,” Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean—neither more nor less.” “The question is,” said Alice, “whether you can make words mean so many different things.” “The question is,” said Humpty Dumpty, “which is to be master—that’s all.”

    LEWIS CARROLL (Charles L. Dodgson), Through the Looking-Glass, chapter 6, p. 205 (1934).

    [Response: I do like that quote. – gavin]

  49. 299
    David B. Benson says:

    Clear Thinker (292) — Chris N just MSU (Makes Stuff Up).

  50. 300
    Populartech says:

    Gavin, no NewsBusters can be very sarcastic but not always. In this case Mr. Sheppard was making a joke about clean air and smog both “causing” global warming. Anyone who understands sarcasm would see the humor in this. It helps to have a sense of humor.

    Hank, yes multiple definitions exist for words. I take it they do not teach this in Europe?

    Oh and David, Mr. Sheppard knew exactly what he was being sarcastic about despite what invented contexts are presented here.