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The carbon dioxide theory of Gilbert Plass

Filed under: — gavin @ 4 January 2010

Gilbert Plass was one of the pioneers of the calculation of how solar and infrared radiation affects climate and climate change. In 1956 he published a series of papers on radiative transfer and the role of CO2, including a relatively ‘pop’ piece in American Scientist. This has just been reprinted (as an abridged version) along with commentaries from James Fleming, a historian of science, and me. Some of the intriguing things about this article are that Plass (writing in 1956 remember) estimates that a doubling of CO2 would cause the planet to warm 3.6ºC, that CO2 levels would rise 30% over the 20th Century and it would warm by about 1ºC over the same period. The relevant numbers from the IPCC AR4 are a climate sensitivity of 2 to 4.5ºC, a CO2 rise of 37% since the pre-industrial and a 1900-2000 trend of around 0.7ºC. He makes a lot of other predictions (about the decrease in CO2 during ice ages, the limits of nuclear power and the like), but it’s worth examining his apparent prescience on these three quantitative issues. Was he prophetic, or lucky, or both?

To understand if Plass should get full credit, we need to see his workings. These are mainly outlined in two more technical papers in Tellus and QJRMS earlier that year. In today’s parlance, Plass calculated the change in top-of-the-atmosphere (TOA) radiative fluxes given a doubling (or a halving) of CO2 while everything else stayed the same. He then took that number and using someone else’s estimate of the sensitivity of the TOA radiation to the surface temperature, he calculated the temperature change that would be necessary to compensate. Converting from the units he used, the radiative flux values for a doubling of CO2 were 8.3 W/m2 and 5.8 W/m2 for clear-sky (no clouds) and averagely cloudy conditions (all-sky) respectively (and slightly larger and of opposite sign for a halving). The sensitivity of the TOA flux to surface temperature he used was around 2.3 W/m2 per ºC (equivalent to a temperature sensitivity of 0.4 ºC/(W/m2)). However, this is a ‘no-feedback’ estimate (allowing only the surface temperature to change with a constant lapse rate, but with no changes to water vapour, albedo or clouds).

Today, our current best guess for the forcing due to 2xCO2 is around 4 W/m2, and the ‘no-feedback’ sensitivity is around 0.3 ºC/(W/m2), giving an expected no-feedback temperature change of about 1.2 ºC, a factor of 3 smaller than the number Plass quoted, though since our number is for ‘all sky’ conditions, it would be a little better to compare it to his averagely cloudy number 2.5 ºC (so a factor of two higher). Note that Plass was a little casual in how he described his numbers and the ‘clear sky’ designation for the 3.6ºC number was not always made clear. However, Plass was well aware that the ‘no-feedback’ case was unrealistic and estimated that the water vapour, cloud and ice-albedo feedbacks would be amplifying, although he was not able to quantify them.

Moving now to the rate of change of CO2 in the atmosphere, Plass made a very good estimate as to how much human emissions of CO2 were increasing. His estimate was (again, in modern units) that then-current emissions were 1.5 GtC based on earlier estimates from Callendar, which actually was an underestimate. Our current best estimate for the anthropogenic emissions in 1956 is about 2.2 GtC. Given the increasing nature of the emissions, Plass then estimated that concentrations would rise about 30% by the end of the 20th Century. This however needs an estimate of how much of the emissions would be absorbed by the oceans and biosphere. Here, Plass has another impressive insight that the ocean chemistry would prevent quick uptake of the human CO2, a concept that wasn’t fully worked out until Revelle and Suess’s paper in 1957 (though possibly he may have been aware of some informal communications earlier). Plass actually assumed that none of the CO2 would be taken up in the short term. So his 30% growth estimate (the actual rise was 36%) was derived from an underestimate in emissions (and emissions growth) combined with an overestimate of the ‘airborne fraction’ (which is roughly 40% of total emissions).

Finally, his estimate of temperature rise of about 1ºC by the end of century follows from the two previous numbers, along with two further assumptions – that the climate is always close to equilibrium with the forcings and that of course, there aren’t any other factors changing. The first assumption affected by the substantial lag in the system because of the thermal inertia of the oceans, and of course, there are many more factors driving climate change over the 20th C. Plass can of course be forgiven for not knowing about the greenhouse impact of rises in CH4, N2O and CFCs (not realised until 1974), or the role of aerosol emissions (1970s), and indeed, he was fortunate that the net effect of all non-CO2 drivers is close to zero (though with significant uncertainties).

So Plass was correct about all of the big issues, but lucky that, in his quantitative estimates, the errors went both ways and end up pretty much cancelling out.

Eli has described this using Isaiah Berlin’s Hedgehog and the Fox metaphor – Plass being the Hedgehog who knows one big thing, and for whom the details are more incidental. I think this is a reasonable take, as long as it is realised that Hedgehogs are not always right, even though in this case he was.

The Fox in this case was another big name in atmospheric physics, Lewis Kaplan. He published a counter to Plass’s 1956 work in Tellus in 1960 (vol. 12, p204-208), and there was a “spirited” exchange of letters in 1961 (vol. 13, p296-302) (references for those of you with libraries – for some reason, none of the old Tellus volumes are online). His calculation used a different methodology, more up-to-date spectra but was different enough in approach and specifics to make a fair apples-to-apples comparison between the results hard to do. Nonetheless, Kaplan declared that “Plass’ estimate of a temperature drop of 3.8ºC due to a halving of [CO2] appears to be too high by a factor of two or three” and that “it would seem, then, that CO2 variations could not play a role in the ice-age cycle unless the changes were by an order of magnitude”.

The subsequent comment and reply are actually very reminiscent of recent disputes in climate science. Plass complains that not enough information was provided to replicate the analysis, that Kaplan used unjustified precision, that he wasn’t comparing like-with-like (all-sky with clear-sky), that he made unjustified technical assumptions, and that his overall conclusion was ‘misleading’ because of the neglected feedbacks (that neither of them had quantified). Kaplan responds that of course there is enough information to check his workings (in another paper), that it was Plass’ fault he compared the all-sky and clear-sky numbers, and that he has exaggerated the impact of the technical criticisms. Notably, Kaplan did not respond on the issue of feedbacks.

Looking over the exchange with a 50 year perspective, a number of things stand out. First, Kaplan does seem to have been closer to modern values in his calculation – Plass was out by a factor of two for the all-sky no-feedback case. I’m not really familiar enough with the details to be be able to tell why (perhaps someone can enlighten us in the comments). However, Kaplan was wrong about everything that has ended up mattering – CO2 does play a big role in ice age cycles (with a magnitude of change close to what Plass anticipated) and its growth today is climatically significant. Significantly, I can find no trace in the literature of any resolution of the technical issues raised in the letters. Resolution in Plass’ favour of the big questions came with further independent efforts as computers got fast enough to do the more complicated feedback problem, better observations, better spectral data and better paleo-climate information (particularly from the ice cores). In some sense, resolution of their technical differences would have been moot because that wasn’t the real issue. Of course, that would have been difficult to see at the time.

So, to summarize, Plass did have some key insights and in many respects was well ahead of his time. But he was also lucky.

Update: Stay tuned, it looks like there is another little wrinkle to this story…

158 Responses to “The carbon dioxide theory of Gilbert Plass”

  1. 101

    Dave Ah,

    I’m actually writing a tutorial on climate models on the science forums at amazon.com, the thread titled (God help us) “Global warming is a hoax and a fraud.” For a good, solid introduction to the subject, either of the following texts would be a great help:

    Houghton, John T. 2002 (3rd ed). The Physics of Atmospheres.

    Petty, Grant W. 2006 (2nd ed). A First Course in Atmospheric Radiation.

    This stuff may help a bit as well:

    http://BartonPaulLevenson.com/Greenhouse101.html

    http://bartonpaullevenson.com/NewPlanetTemps.html

  2. 102
    Dave Ah says:

    To 103 Barton Paul Levenson:

    Many thanks for the pointers provided.

  3. 103
    Jim Bouldin says:

    Nice article! Wouldn’t mind seeing more like it, including from Spencer.

  4. 104
    Stuart says:

    To 102:
    “Do the authors suggest a means of transport of heat away from the planet, once it has been moved from liquid water to water vapor? There’s something missing in the explanation, but perhaps the authors account for that?”

    Barrett accounts for that here:

    http://www.warwickhughes.com/papers/barrett_ee05.pdf

    The contribution of carbon dioxide to the total global warming of 34.2 K may be
    calculated to be 6.7 K from the results of Table 2. That assumes that radiative transfer
    is the only mechanism whereby heat is transferred from the surface to the atmosphere.
    The global energy budget2 indicates that the warming of the atmosphere has a major
    contribution from the latent heat of evaporated water of 78 W m–2. If this is converted
    into a radiative flux, the total radiative flux would be 390 + 78 = 468 W m–2 which
    would be emitted by a surface with a Stefan-Boltzmann temperature of 301.4 K, a
    global warming effect of 301.4 – 253.7 = 47.7 K. Thus, the effect of water evaporation
    is to cool the surface by 47.7 – 34.3 = 13.4 K. These results are shown in Figure 8.

  5. 105
    Doug Bostrom says:

    Stuart says: 6 January 2010 at 7:05 PM

    Ok, so the energy is transferred into the atmosphere, where it radiates. Whither from there?

  6. 106
    Shirley says:

    Ok… I don’t know why i do this to myself, especially when I have so many projects demanding my attention right now, but I’ve spent a few hours at Barret & Bellamy.

    First, a glaring problem: NO REFERENCES OR CITATIONS! Nothing! Not on any of the many pages I read. And I’m talking about things upon which I agree, such as the assertions made about biofuels. I did a great deal of research on biofuels about 3 years back, and I agree with the general characterizations made. However, numerous statements are made about costs of production and so forth and no authors, sources, etc. given. Believe me, there is a lot more data and research on these subjects now than 3 years ago (I still keep up with it peripherally, and Pimentel was almost all we had back then) and they give no sources, and it’s the same story on any of the hard-science pages. It’s one thing to not source something that has been well established like Planck’s constant, but the claims made on pages like “Is it the Sun?” and “A Simple model” and a dozen others also contain no references, while making very specific scientific claims. And now I see why the publication Energy & Environment has been called into questions here at RC, because lo and behold, the article by Barret posted by Stuart above (currently #106 but I know that is fluid during bulk updates) also has but one reference, although he lists another which really isn’t a reference.

    No one just pulls hard scientific facts magically out of the air. The Barret paper mentioned above is mostly about chemical/physical properties of certain GHG molecules as they react with infrared radiation. Did he conduct experiments to learn these things? If so, what are his methods? If not, how did he learn these things? This is what citations are for – not only to prove one has done their homework, but so that the reader may go back and read that work to inform themselves and understand – and question – the methodology used to make the claims put forth. In my first major undergrad paper, I listed 25 references.

    I don’t see much that is published in reputable journals with less than 15-25 references. It’s very rare, because few of us will ever come up with a novel idea; we are all building upon the science before us. Give credit where credit is due, not only as a service to the scientists who have worked hard before us, and published their references, but to the readers we seek to serve who may further themselves by those citations.

    So ultimately, that makes the Barret & Bellamy site a “Because We Say So” website and nothing more. They’re using figures for which they don’t explain the origins or methodology in developing them (assuming they didn’t come from elsewhere), and seem to selectively use NASA figures where it suits them. Take a look at the second figure on CO2 distribution on the “Assymetric World” page:
    http://www.barrettbellamyclimate.com/page29.htm

    They don’t make it clear if the graphic is theirs or NASA’s, only that it is NASA data. Regardless, the claim they make about lack of mixing seen is less credible if one looks at the color bar scale used in the image. At 365-370ppm, the colors are distinguishably no more than two per that range. At 370-375, that range also uses really only 2 distinguishable color variations, but from 375-380, depending on how good your vision is and how you want to mentally correct for an image that small, there are 4-7 distinct colors within that range, above that, essentially 2 colors. The 365-370 region is also dominated by dark blue (making a visual estimation, about 75%), 370-375 by cyan (about 75%), and 375-380, about 25% yellow, with a difficult to distinguish green at second. Is it a wonder then that the map is dominated by yellow, pale green and cyan? This is a tactic Monckton and others use – lying with maps/graphs. Perhaps they’re not doing it on purpose, but it proves they’re sloppy if nothing else.

    Another glaring issue is on the “Is it the Sun?” page. Basically, they start out using a graph with no citation, showing “correlation” of sunspot activity with temperature. The problem is, which they don’t mention, is that if you only scrutinize the first part of the graph (the left side), it correlates well, but as many of us know, if you keep looking to the right, it breaks down after the 1970s. Unfortunately at the scale this diagram appears, that’s difficult to see, and they don’t mention it. Someone said earlier that they see to be honest. It’s not looking that way to me.

    It gets even worse at the bottom of this brief treatment of a complex, pretty well studied issue (again, no refs) where they almost flatly make the claim… without quite making it… that Jupiter causes the 11 year cycles. SO I guess the answer is that it’s Jupiter, not the sun.

    No reputable scientists argue that the sun doesn’t play a role in climate, just not the only one, and I’m realizing now that while these people do give credence to the greenhouse effect, they want to dismiss it as quickly as they acknowledge it.

    They, like many others, like to claim that the planet hasn’t warmed lately (it hasn’t shown any significant cooling, either, despite the long solar minimum http://data.giss.nasa.gov/gistemp/graphs/
    http://www.sciencedaily.com/releases/2009/01/090116163206.htm) but don’t mention the deep solar minimum we’ve been in for quite some time now (look: references http://solarscience.msfc.nasa.gov/SunspotCycle.shtml), so as far as I can tell, they are engaging in the telling of half-truths, with just quiet subtle spin, but enough for me to think it’s intentional. Like many others, they’re ignoring the numerous aspects of science, selecting only those which support their case.

    Another aspect to their “case” is that they claim the southern hemisphere isn’t warming (again, they provide no references to any data, so I can’t post a link to anything that supports this premise) and simultaneously claim that Antarctica isn’t warming, which again, makes them look bad, because the cold weather feedback mechanism between the ozone hole and the Antarctic is well established (http://www3.interscience.wiley.com/journal/114054922/abstract http://www.sciencedaily.com/releases/2009/04/090421101629.htm and there are lots more out there, easy to find) and air flow and atmospheric thickness are different at the poles than other regions (the Wiki is as good as any… I’m tired at this point http://en.wikipedia.org/wiki/Atmospheric_circulation and it’s intro textbook atmospheric stuff, and think about how the Earth bulges at the equator, where the atmosphere is thicker, rotation speed is different, Hadley cells, etc).

    The impression I get is that Barret and Bellamy are re-packaging the same old half-truth bunk into a friendlier package, without all of the political world takeover stuff. I’ve looked at enough pages (many of which I didn’t even get into, and just as flawed and half-true as the rest) to believe that calling them honest is, in my opinion, too much of a stretch. Whether they’re being deliberately dishonest to fool others or just happily fooling themselves is another question, one I wouldn’t claim to be able to answer. If the lack of citations is just laziness, I don’t know that reflects any better upon their character.

  7. 107
    John E. Pearson says:

    108: I don’t want to spend a great deal of effort defending those guys but … Normally when arguing with denialists I feel like a rabid chimpanzee has broken into my house and is attacking me. He’s throwing stuff at me: one moment pillows, the next my butcher knives, then water balloons, then the kitchen sink, then my shoes, then my Yucca plant, then my dining room chairs, then the dumb bells etc etc etc. Total random incoherency. Those guys seems to me to be honest and harped mainly on a single issue. They linked to Fred Singer’s page. They lose points for linking to rabid chimps, but if politics weren’t involved and you were going to discuss whether AGW was an issue and you wanted someone taking a contrary position, I’d sooner it was those guys than pretty much anyone else I’ve seen. Crichton? Lindzen? Spencer using a model with four free parameters to come up with a model that had a decent temperature anomaly without an AGW attribution jeez? I didn’t read the biofuels page. I don’t see how one can have a single opinion on biofuels. There’re are all sorts of ways to implement biofuels.

  8. 108
    Hank Roberts says:

    Thank you Shirley! Wonderful, blunt, clear takedown of Barret & Bellamy.

    > First, a glaring problem: NO REFERENCES OR CITATIONS!…
    > … re-packaging the same old half-truth bunk into a friendlier package,
    > without all of the political world takeover stuff. I’ve looked at enough
    > … just as flawed and half-true as the rest) …. too much of a stretch.
    > If the lack of citations is just laziness, I don’t know that reflects any > better upon their character.

    Clunk.

  9. 109
    Ernst K says:

    By the way, for those wondering how the Barret & Bellamy model treats evaporation, here it is:

    The default non-radiative heat transfer from the surface is 102 W/m2

    The model calculates the net non-radiative heat transfer as = 102 + 102*0.067*Delta_T

    Delta_T = change in temperature from current (~288 K)

    The extra non-radiative heat from the surface means the surface needs to emit less radiation so it’s cooler.

    This is the evaporation effect that isn’t accounted for in the GCMs.

    Laughable.

  10. 110
    David Horton says:

    Shirley #108 “Another aspect to their “case” is that they claim the southern hemisphere isn’t warming (again, they provide no references to any data, so I can’t post a link to anything that supports this premise)”. Well, no, in Australia – Warmest. Decade. Ever. Even the weatherpersons on commercial television seem aware of that fact now. Second warmest year on record for Australia (after 2005, both ahead, remarkably, of extreme El Nino 1998), fifth warmest globally. Highest temperatures extending right through NSW and SA, very low rainfalls for same area – Australian Bureau of Meteorology climate statement 2009 http://www.bom.gov.au/announcements/media_releases/climate/change/20100105.shtml

  11. 111
    Deech56 says:

    New visitors and new posters (actually, anyone) may be interested in Robert Grumbine’s recent post on the correlation between CO2 and temperature. His site is a good place for the curious to ask questions.

  12. 112
    drew3000 says:

    To TRY Re: #25…
    Glaciers and other natural phenomenon are different from thermometer and weather stations in a number of ways already mentioned here. But it’s also worth pointing out that they also contain evidence of what was in the air at various given times in history. You can see the difference in layers at different periods of time. they offer far more ways to look at the state of climate. The weather station and thermometer or no doubt useful tools in accurate measurements, but they don’t tell the whole story by a long shot. Records found in natural events offer a far more comprehensive picture.

  13. 113

    Stuart,

    The surface cooling due to evapotranspiration has been taken into account by climate models for a long, long time. The earliest approach (Manabe and Strickler 1964) was to subsume sensible and latent heat transfer under a “convective adjustment.” Later models calculated each flux. Trenberth et al. (2008) estimate that the Earth’s surface cools at 391 watts per square meter by radiation, 80 by latent heat (evapotranspiration) and 17 by sensible heat (conduction and convection). The climatologists haven’t missed anything. It’s their job not to.

  14. 114

    Ernst: This is the evaporation effect that isn’t accounted for in the GCMs.

    BPL: It damn well IS accounted for in the GCMs. Have you ever read the source code or documentation for a single GCM? Or even an RCM?

  15. 115
    Eli Rabett says:

    Barrett has a long history of cherry picking factoids, omitting stuff and then digging in. There were several sci.environment discussions about a paper he published in Spectrochemica Acta in the eighties along the same lines. At least he does appear to have learned something about radiative transfer. (had to use a tinyurl to avoid the spam trap)

    Thank you Shirley

  16. 116
    Eli Rabett says:

    Ike, the interesting thing about coal to gasoline is to use hydrogen generated by solar and wind. Also you use the heat you generate in going from coal to the synthesis gas for electrical and process work. You should be able to double the amount of energy per unit CO2 emitted, and you get to use most of the in place fuel infrastructure.

  17. 117
    Shirley says:

    109 John E. Pearson: I see your point… thanks for the chuckle… and the yucca plant. I agree, I’d rather people get their info from a source that isn’t foaming at the mouth or choking on tea bags, but I felt like someone needed to call them out. I’d still love to have those hours back, but it probably won’t be the last time. Why do I do this to myself??? ;)

    110: Hank, coming from you, the is a really high complement. I hope I saved you some of that eyeball gouging time I put myself through!

    112: David Horton. THANK YOU because Australia was the first thing that came to my mind, and I was already too distracted with link-getting to go find that, too.

    Yes, good people reading, it is troublesome to get and put in references, and I believe only one of mine would cut the muster of a reputable, peer reviewed publication, but you see, this was something I threw together in a couple of hours, and not for some very serious website of my own. Imagine what could be done with lots of time and oil $$ funding one’s endeavors. There is absolutely no excuse for the lack of citations on their website and especially not in their papers. Again, if not for all of the obvious reasons, but so that their readers can further their own education by reading the sources from which Barret and Bellamy learned. Or are they like priests telling their parishioners not to read the bible?

    I thought about another tactic they seem to be using, unless it’s just that they’re bad at explaining simple scientific details. They have a lot of pages with some basic physics equations. Most of this stuff (I probably haven’t looked at every page at this point) is intro physics found in any undergrad intro text books. Most of these equations have names, which they didn’t use. They also didn’t explain how these equations work very well (most of the ones I looked at closely had to do with emissivity and reflectivity, IOW blackbody radiation) which is either a shortcoming in their ability to teach, or a low expectation of what their readers can comprehend, or, what I suspect given the other details, is that they want to use just enough math and make it look just arcane enough that the reader won’t question it and instead say to themselves “Oh, they’re so much smarter than I am so they must be right.” This is a favorite tactic of Monckton, but he’s just much more smug and snide and obvious (and rabid and foaming at the mouth and…) about it. I do agree with John E. Pearson that it’s much better that Barret and Bellamy present in a rational, mostly dispassionate manner (they’re not calling climate scientists liars and distance themselves from conspirists) and it’s possible that they truly believe their own distortions, but they’re still distortions.

    I’ll bet none of the deniers call make note of this Plass article. Surely they could find some contrarian message in it, but they don’t want there readers to know that climate science is not new, and is not just in the hands of a few elites. This is why coming here is so refreshing. So many bright people, professionals and hobbyists, sharing what they know. Thanks, everybody.

  18. 118
    Rod B says:

    ErnstK (94), et al: jumping into the middle, I would like a clarification of a detail in the statement, “…As the water evaporates, and H20 enters the atmosphere the air temperature increases (quite a bit, based on my understanding of the trace gas effect).” Doesn’t the air temperature increase only after the evaporated H2O condenses to rain or clouds?

  19. 119
    Ernst K says:

    BPL,

    You misunderstood. When I said …

    Ernst: This is the evaporation effect that isn’t accounted for in the GCMs.

    I was repeating what was said on the Barret and Bellamy website and quoted by Stuart in post 93.

    And by “laughable”, I meant that it’s laughable to use such a simplistic approach to evaporation and then claim that it represents a feedback mechanism that is missing from GCMs.

    For the sake of my own reputation, I guess I should have been clearer.

  20. 120
    Hank Roberts says:

    > Eli Rabett says: 7 January 2010 at 8:50 AM
    >
    > Ike, the interesting thing about coal to gasoline is to use
    > hydrogen generated by solar and wind. Also you use the heat ….
    > should be able to double the amount of energy per unit CO2 emitted,
    > and you get to use most of the in place fuel infrastructure.

    Now this gets interesting if you use the oxygen as well, in combustion, instead of using atmospheric air. That avoids the nitrogen oxides problem (with excess nitrogen being a huge biological problem nowadays). And produces a waste gas stream that’s almost entirely CO2, ready to sequester or resell to the fizzy water companies.

  21. 121
    Geoff Wexler says:

    What would have happened if Plass had been asked to review Barrett?

    Re : Barrett, 2005, En. & Env. 16

    Here are my immediate impressions. Its not just the latent heat problem.

    Plass might have agreed that the author has some rudimentary knowledge about the problem. That would be his reaction to the introductory paragraphs. But what about the greenhouse effect and the radiation transfer?

    Would Plass have withdrawn his own paper as a result of receiving this draft? Well Plass had tackled the saturation problem which included the effect of overlap mentioned by Barrett.

    So has Barrett done it properly? It looks as if he has tried to obtain general conclusions by looking at the first 100 m of atmosphere. Where does Barrett mention the re-radiation from the top of this layer?

    Where does Barrett mention the effect of the decrease of pressure with height?

    In his conclusions he states “the whole atmosphere being equivalent to one of 8 km at a pressure of 1000 mb and a temperature of 288 K.”

    This reminds me of work by Angstrom’s son in about 1900, which Plass helped to overthrow. That early work made the mistake of relying on observations at ground level at one temperature and pressure.

    Barrett states:

    “In the presence of the other GHGs the same doubling of concentration achieves an increase in absorption of only 0.5%, only one third of its effect if it were the only GHG present. Whether this overlap effect is properly built into models of the atmosphere gives rise to some scepticism.”

    This seems worse than pot’s calling kettles black considering that this own ideas are based on a warm 100 m layer near the ground which can hardly contribute much to the overall greenhouse effect.

    Perhaps this paper should be classified in the category “Misleading simple models a la Monckton” .

  22. 122
    Brian Dodge says:

    I looked at the 2 graphics at http://www.barrettbellamyclimate.com/page29.htm, and it scares the crap out of me. There’s a difference of about 15ppmv in CO2 between the Northern and Southern hemispheres,and that’s causing about a 0.4 deg/decade rise in NH temperature. With CO2 rising about 20 ppmv per decade, temperatures should be rising by an additional (0.4/15)*(20*3)=1.6 degrees per decade in 3 decades. If their asymmetry argument is correct, in 30-40 years, we will be at the low end of IPCC predicted CO2 doubling sensitivity, with only 440ppmv CO2 (1.6X), no “in the pipeline” warming accounted for, and an eyeball overestimate of the difference in CO2 between NH and SH. If the delta T/delta CO2 sensitivity implied by asymmetry is accurate, we may be as badly surprised by temperature changes in the next 4 decades as we were by the Arctic summertime sea Ice minima in the last two – http://www.woodfortrees.org/plot/nsidc-seaice-n/from:1989.6/every:12.

    OTOH, It’s possible that in an attempt to minimize AGW, they are confusing themselves by comparing apples to oranges (hemispheric DCO2 to DT). Maybe someone should send them a copy of Arrhenius’s seminal paper, with the parts about snow-ice albedo and land-ocean differences highlighted; and NH + SH maps.
    In a boot.
    With instructions printed on the bottom.

  23. 123
    Susan Anderson says:

    Shirley, you rock (if you’ll forgive the expression).

    Dave Ah, from a fool who rushes in and knows less than you, would recommend Spencer Weart’s Discovery of Global Warming. He also has an expansive website:
    http://www.aip.org/history/climate/index.html#contents

    There are a good few useful references here too.

    On water vapor maps, I love this animation (there’s lots more)!
    http://weather.unisys.com/satellite/sat_wv_hem_loop-12.html
    Also on the site are are other maps such as IR which (to my untutored eye) provide physical/data backup.

    (from Tenney Naumer). Tenney’s blog (1/6ish) is exploring recent Arctic weather and anomalies, Artic Oscillation etc.
    http://climatechangepsychology.blogspot.com/

    Apologies for earlier rant re climate consequences. It is exhausting watching the decades unfold without population-wide understanding of all the work that has been done and confirmed.

  24. 124
    Doug Bostrom says:

    Shirley:

    “…what I suspect given the other details, is that they want to use just enough math and make it look just arcane enough that the reader won’t question it and instead say to themselves “Oh, they’re so much smarter than I am so they must be right.”

    Works for me; they could probably put in non-annotated equations describing lemming population cycles and I’d be impressed. Both of my brothers are brilliant with maths, as was my dad. Me, it all turns into a grey blur and passing exams was a matter of becoming some sort of semi-intelligent flash memory stick with poor long term retention. I -know- I fell on my head once and almost drowned twice as a kid, maybe that’s the issue…

  25. 125
    Ernst K says:

    Rod B says:
    7 January 2010 at 10:44 AM

    ErnstK (94), et al: jumping into the middle, I would like a clarification of a detail in the statement, “…As the water evaporates, and H20 enters the atmosphere the air temperature increases (quite a bit, based on my understanding of the trace gas effect).” Doesn’t the air temperature increase only after the evaporated H2O condenses to rain or clouds?

    I was talking about a hypothetical Earth where you’re adding water to a totally dry (in terms of H2O) planet with lots of CO2 (not Venus lots, but more than current Earth, enough CO2 – or any other GHG except water – that the new water wouldn’t all immediately freeze) rather than the real case where we’re adding CO2 to a planet with lots of H2O.

    As such, I am talking about the greenhouse effect due to the new H2O and the feedback loop it would generate, not the heat transfer effects of evaporation and condensation.

    I fully admit that this is more of an academic exercise.

  26. 126
    Brian Dodge says:

    “I’m a contrarian by nature, and some of the comments directed at me here have been ‘nasty’ and ‘patronizing’ so it’s definitely made me more of a contrarian on this issue.” TRY — 4 January 2010 @ 6:37 PM

    “I expect blood on the carpet.” Eachran — 4 January 2010 @ 3:11 PM

    I’m one of the occasionally nasty and patronizing, as well as rude and sarcastic commenters here, but most of my comments get through, probably because I try to include supporting references, and I self edit(you should see some of the things I have written but not submitted). But I merely trod on the toes of giants – most everybody is familiar with Pauli’s “not even wrong” putdown; I found another, um, “strongly expressed opinion” among fairly well known scientists –

    “What Schrödinger writes about the visualizability of his theory ‘is probably not quite right,’
    in other words it’s crap.”
    –Werner Heisenberg, writing to Wolfgang Pauli in 1926 from http://www.aip.org/history/heisenberg/p08.htm

    These guys graded on a pretty steep curve.

  27. 127
    Spaceman Spiff says:

    Shirley@108:

    As with John E. Pearson@109 I won’t defend some of Barrett & Bellamy’s interpretations of the data or conclusions drawn, but as with John E. Pearson, I too was shocked to see a decent presentation of introductory atmospheric radiation physics, without all the non-starter non-sense, and the fact that they bothered to take to task many of the so-called arguments commonly put forth against AGW.

    A few comments with regards to a couple of your (and others) criticisms:

    1) IMO the very basic equations presented really don’t need annotating or referencing. They obviously expect that the reader has some background in the physical sciences and maths, roughly at the level of an undergraduate physics student.

    2) One of the areas of Prof. Barrett’s expertise is/was in the spectroscopy of atmospheric molecules, and he probably didn’t see the need to substantiate and reference the molecule/radiation processes. However, I do agree that they’d have made a much better scientific case if they had bothered to provide references for each of their major topics, especially with regards to claimed evidences pro/con of their interpretations and drawn conclusions.

    3) The more pages I read, the more it sounds like a couple of curmudgeonly scientists expressing their “beefs” regarding areas of climate sciences that happen to intersect with their (long past) research expertise, while at the same time being in way over their heads with regards to the state of the climate science literature. This last bit is a killer if one’s goal is to raise consciousness within the scientific community.

    And if you do a literature search on these two guys, you’ll find that they’ve cut themselves off from being taken seriously by the climate science community by making very strange and unsubstantiated claims.

  28. 128
    David Miller says:

    Re discussions of coal-to-gas with hydrogen from RE (#122)

    While I’d love to see it – particularly with Hanks vision of sequestering the CO2 stream, I don’t see it happening. With the cost per BTU of coal it’s going to be way cheaper to just add water to the combustion and end up with more CO2 to go with the CO and H2.

    The possible exception to that is utilizing wind energy in excess of current demand, but we’re quite a ways from having a reliable supply of that. And even that counts on the CTL technology being developed before some form of electrical storage.

    It would be a semi-cool way to produce liquid fuels, but I don’t expect to see it in my lifetime (I’m currently pushing 50).

  29. 129

    Ernst,

    I apologize, I didn’t realize you were being sarcastic.

  30. 130
    Ernst K says:

    BPL @ 131,

    Yes, I get that a lot, you’d think I would learn. :)

    Thank you for letting me know that you now know what I meant …

  31. 131
    Geoff Wexler says:

    re: #129

    One of the areas of Prof. Barrett’s expertise is/was in the spectroscopy of atmospheric molecules, and he probably didn’t see the need to substantiate and reference the molecule/radiation processes.

    He is a chemist. As for his being an expert on spectroscopy, we have to ask why his 2005 E. & Env. paper appears to neglect the pressure dependence of these spectra? Either because he thought that it had no effect on the conclusions or that he did not want to know about it.

  32. 132
    Eli Rabett says:

    Hank (#122) there is another way around that which gets rid of the NOx and the N2.

  33. 133
    Eli Rabett says:

    Spaceman when you say

    “As with John E. Pearson@109 I won’t defend some of Barrett & Bellamy’s interpretations of the data or conclusions drawn, but as with John E. Pearson, I too was shocked to see a decent presentation of introductory atmospheric radiation physics, without all the non-starter non-sense, and the fact that they bothered to take to task many of the so-called arguments commonly put forth against AGW.”

    in Daniel Moynahans words, you are defining deviancy down.

  34. 134
    Spaceman Spiff says:

    re.#133

    His Ph.D. was in physical chemistry. I assumed he knew something about molecular spectra because of some of his publications (and his own mention of such on the “about” page).

    As for why he might have ignored important physics. Beats me. I didn’t say anything about his abilities, only that he ought to have known about how these relatively simple molecules behave spectroscopically at the level of presentation.

    Based on some of his references I’ve perused, I am sure he knows about the existence pressure broadening. Again, I’m not defending these guys’ scientific arguments.

    As a matter of fact the more pages I read, the more disappointed I become. The spectrum in the figure here is lifted from A first course in Atmospheric Radiation by Grant Petty, and the spectra presented the two figures here and here were generated from David Archer’s MODTRAN webpage. They do not credit their sources on these particular pages, as they should, although they do provide a list of links that happen to include the origins of these figures.

  35. 135
    jrs says:

    Re: posts 7, 42 and 112: The situation here is that – for instance – the Sydney region received about 75% of its long term average rainfall this year, despite a small blip at the end of the year, caused by the break up of a Cat. 5 tropical cyclone over/adjacent the Kimberleys (opposite side of the country). The small blip of course delivered a significant dump of rainfall over parts of the country that have been in technical drought for half a decade or more. The denialists are claiming that it marks the end of the drought, that normal service will now be resumed, though even the Farmer’s organisations are warning that follow up rains are required.
    As post 112 pointed out, the year set some heat records (both last summer and mid winter) and therefore set records for soil drying and lack of runoff. Flooding occurs more becase the land out there is essentially flat. Quite ‘small’ amounts of rain simply spread out over vast areas. So the eternal problem for Australia’s (inland) farmers: straight from drought to flood and back again. I wonder if the current freeze in Northern Europe (and China and the US) has some similar central trigger?

    regards to all and I love this site even when it gets a bit too techie for me

  36. 136
    Spaceman Spiff says:

    Eli Rabitt@135: in Daniel Moynahans words, you are defining deviancy down.”

    Yeah, I suppose I am. The anti-science crap on the web is so awful that when I encountered Barrett & Bellamy’s website, particularly their tutorial on atmospheric spectra and their undressing of some of the more common BS talking points, I about fell off my chair. But the more I investigate their musings on climate (on that set of webpages and in papers elsewhere), the less impressed I become. And this is just about as good as it gets. How depressing.

  37. 137
    Eli Rabett says:

    Barrett is not an expert in the spectroscopy of atmospheric molecules as anyone looking at his list of publications could tell.

  38. 138
    Edward Greisch says:

    101 Hank Roberts: Plutonium240 [from power plants] makes bombs that the Department of Defense [DOD] doesn’t want. They fizzle, yielding only 200 tons equivalent. Not worth bothering with. Bad for logistics. DOD wants only efficient Pu239 bombs. DOD makes its own Pu239. Pu239 is hard to make and requires a specialized reactor. [ANY plutonium bomb [implosion device] requires technology that is beyond most countries.] Forget about this subject. With apologies to RC.

    Thorium has another problem: It has to be bred into uranium233 in a reactor before it is fuel. That process has political problems.

    I would guess that they got an order from the president to forget about gasoline from coal. Gasoline from coal has too many problems to count.

  39. 139
    san quintin says:

    It’s also worth mentioning that Bellamy isn’t a climate scientist…he works (or worked) on the ecology of peat bogs if I remember right. He famously talked a load of nonsense about glaciers and climate change a few years ago. maybe he should stick to what he knows. I’m always amazed at the arrogance of people like him suggesting that they have unique insight into radiative physics (that all the physicists have somehow missed).

  40. 140
    Completely Fed Up says:

    jrs: “The denialists are claiming that it marks the end of the drought, that normal service will now be resumed, though even the Farmer’s organisations are warning that follow up rains are required.”

    It’s the next step of delay, jrs.

    “It’s all reversing, so don’t change a thing”. But it takes time to prove it isn’t reversing (see the “it’s been cooling since 1998 [despite that being CRU data that has also been “falsified” to the satisfaction of the same people]” meme. It’s STILL going).

  41. 141
    Ray Ladbury says:

    “The LC09 choice of dates has distorted their results…”

    Coincidence? I don’t think so…

  42. 142
    Ray Ladbury says:

    Barrett & Bellamy’s website: There’s less there than meets the eye…

  43. 143
    Bio Char says:

    @88 & @130
    Ike, thanks for posting, i just missed in your comment a hint to negative carbon technologies.

    The pyrolysis technique producing charcoal/biochar to seal greenhouse gases into the soil and at the same time enhance crop productivity, get gas/fuel as by product and several other positive factors.

    There is now a good book on the matter: J. Lehmann 2009: Biochar, Environmental Management

  44. 144
    Geoff Wexler says:

    Any Barratt/Bellamy enthusiasts here should not misunderstand this sub-thread. It is not intended to be comprehensive. I just stumbled on another joint essay by these two and it is certainly not moderate. It has more in common with the other denialist stuff than some of the above comments might suggest. For example , some of it is not aimed at scientifically educated people but is pure spin. But I did not see any personal abuse.

  45. 145
    Hank Roberts says:

    Shirley — please, keep posting.
    Your and Eli’s comments above are worthy of the RCWiki (link at top), which has an item for Bellamy but not one for Barrett yet.

  46. 146
    Stuart says:

    Thanks for the many responses to the questions on CO2 concentration on temperature and water feedback. I’d like to pose another question. As Barret’s graph for CO2 versus temperature shows (and I think that this graph is considered to be uncontroversial and accepted):

    http://www.barrettbellamyclimate.com/page24.htm

    The temparature in the absence of CO2 is 278K and it rises logarthmically and asymptotically approaches about 290K.

    [Response: This is actually a little misleading. They are calculating the ‘no-feedback’ temperature change, but this is not going to be the planetary temperature change when CO2 changes. So putting it on the absolute scale K is a bit sneaky. PS. you understanding the word asymptote is not correct. The graph continues to rise past 1000ppm. – gavin]

    It predicts a temperature of about 289.7K for today’s level of CO2.

    [Response: That’s not a prediction – it’s where it’s calibrated. – gavin]

    As most people here have pointed out – the graph apparently does not take water vapor feedback into account. Therefore in reality doubling the CO2 will give a higher increase than just 1.5C. However, doesn’t even the present level of CO2 cause water vapor to increase? What causes that level of extra water vapor in the atmosphere to suddenly stop growing? It’s almost as the water contribution is self-limiting – as if it’s acting as some kind of thermostat. Why would increasing the CO2 make water vapor stop working as a thermostat to limit any temperature increase.

    [Response: You have this completely backwards. Water vapour amplifies the changes driven by CO2 – in what ever direction. If CO2 goes down then so will WV and the planet will cool by more than if it was just CO2 changing. A large amount of the WV currently in the atmosphere is there because CO2 has made it warm enough. – gavin]

    But again, although water feeding back on itself may be a rhetorical question (since it obviously doesn’t happen otherwise thery’d be a runaway affect and unstable climate)

    [Response: Again no. It can feedback on itself, but the series is convergent i.e. 1 + 1/2 + 1/4 + 1/8 so there is no runaway effect. – gavin]

    – why should the system respond differently to a temperature increase caused by CO2 and a temperature increase caused by extra water vapor? It’a almost as if the system is saying “OK I’m experiencing a temperature increase due to increasing CO2 so I’m going to evaporate water as a result” or “OK I’m experiencing a temperature increase due to increasing H2O but I’m not going to evaporate water this time”.

    Is there any possibility that what really happens is that the extra water does evaporate but the weather system ensures that the relative humidity stays constant with various mechanisms such as surface cooling from evaporation, cooling from IR photon emission in the upper atmosphere (once evaporated water condenses into clouds heat is released and the heat is transferred to N2 and O2 which than radiate half of it into outer space.

    Isn’t the only way to explain the lack of water feeding back on itself with one of these mechanisms? And wouldn’t one then conclude that there is no significant positive water feedback mechanism?

  47. 147
    Spaceman Spiff says:

    Stuart@150:

    As Gavin said, WV can feedback on itself. But really, what is happening is that water vapor is just responding to temperature, regardless of how it gets there. The series he mentioned converges to 1/(1-f), where f is the amplifying feedback factor (for 0 < f < 1) or damping factor (for -1 < f 560 ppm) without feedbacks. Then for a value of f = 2/3 (say), the net temperature increase (when/if equilibrium is re-established) is +1.2 / (1-2/3) = +3.6 degrees C with the feedbacks in play. In principle one can perform this estimate for all of the feedback mechanisms (+ or -) to get a net sensitivity.

    Read Knutti et al. (2008), and in particular read the discussion pertaining to Figure 2.

  48. 148
    Spaceman Spiff says:

    Skeptical Science has two nice articles on climate sensitivity here and here.

  49. 149
    Spaceman Spiff says:

    Re: #147 —

    Dang. Somehow my post was massacred. Here is what it should have said:

    Stuart@150:

    As Gavin said, WV can feedback on itself. But really, what is happening is that water vapor is just responding to temperature, regardless of how it gets there. The series he mentioned converges to 1/(1-f), where f is the amplifying feedback factor (for 0 < f < 1) or damping factor (for -1 < f < 0). Let us suppose that the temperature sensitivity for a doubling of CO2(from 280 to 560 ppm) without feedbacks is +1.2 degrees C. Then for a value of f = +2/3 (say), the net temperature increase (when/if equilibrium is re-established) is +1.2 / (1-2/3) = +3.6 degrees C with the feedbacks in play. In principle one can perform this estimate for all of the feedback mechanisms (+ or -) to get a net sensitivity.

    Read Knutti et al. (2008), and in particular read the discussion pertaining to Figure 2.

  50. 150
    Ernst K says:

    Stuart @ 146

    Is there any possibility that what really happens is that the extra water does evaporate but the weather system ensures that the relative humidity stays constant with various mechanisms

    The amount of warming from water vapour depends on the actual humidity in the air, not the relative humidity. So even if the RH stays constant, if the average temperature of the atmosphere increases then the actual humidity (technically, the partial pressure of water vapour) will increase.

    To prevent a positive feedback mechanism, you need the relative humidity to drop, and drop by quite a bit since the saturation level for water vapour is a nearly exponential function of temperature: for every 1 deg Celsius of warming, the saturation pressure of water vapour increases by 6 to 7%.

    On a side note, I think I now know where that 0.067 in the B&B evaporation equation comes from.

    Apologies in advance if my experiment with html doesn’t work.