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Playing Devil's advocate on climate

  1. Sep 19, 2009 #1
    This is a fascinating forum, and these climate discussions are very interesting and educational. I couldn't help but notice however that it seems posters tend to line up along sides on the issue of AGW (or perhaps the degree to which they are skeptical of the consensus). I think it would be interesting to see people play devil's advocate and argue for the other position, or rather acknoweldge data that does not support their view (on both sides).
  2. jcsd
  3. Sep 19, 2009 #2


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    Yes, that's right. That's what we try to do for ages here, but several people tend to pick sides from the start. Not only on PF. It seems to be a trench war, instead of a scientific debate.
  4. Sep 19, 2009 #3
    Isn't that the 'holy' duty of science, to play devils advocate? Either strenghten the human corporate knowledge, if there are no flaws to find; or stop going into the wrong direction if the ideas turn out to be flawed.

    That has everything to do with falsifiability and reproduceability and it never stops. You can't prove a theory to be right but you can falsify it according to Popper.

    While falsifiabiltiy is rather rigid and can be disputed on statements that are too black and white, it doesn't warrant that theories should be shielded against attempts to falsify it. But much more significant, if that happens, what does that say about the trustworthiness of said theory amongst their adherents? Anybody noticed how many http://www.arts.auckland.ac.nz/online/sociol318/week4.html [Broken] we have nowadays, known as deniers? Could that be the result of many ad hominem attacks against people who are merely doing their job?

    There is yet another way to shield global warming effectively against falsification, that's simply by declaring what ever happens, cooling or warming, http://www.aber.ac.uk/media/Students/hrb9701.html:

    However, if something is not falsifiable anymore, is it still science?

    Also, what strong warming anyway?


    Source: http://www.ssmi.com/msu/msu_data_description.html#figures
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  5. Sep 19, 2009 #4


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    The problem is, Andre, that the "deniers" have also a theory to defend, namely that extra consumption of fossil fuels and the exhausted CO2 in the atmosphere has NO possibility to give rise to any observable warming over several hundreds of years. That's also a pretty strong statement that should be defended.

    This is why there is no "default" position and a "challenger" position here. There are two theories, one that should theoretically demonstrate that CO2 cannot have any observable effect, and the other that should indicate what is the mechanism by which CO2 could give rise to some warming. I think that the first theory is making the strongest claims, actually.

    As to the second theory, the difficulty is now to establish HOW MUCH warming it could cause.
    Is it going to be 0.1 degree, or 1 degree, or 2 degrees, or 5 degrees, or 10 degrees, or 15 degrees or ... ? That's a matter of numerical accuracy of the theoretical models.

    It is true that simple atmospheric physics indicates *a priori* a (modest) warming, all else equal. So defenders of the "no warming possible" theory should demonstrate that this basic effect has to be cancelled out exactly by some more involved mechanism. Defenders of high warming values, should demonstrate the existence of strong positive feedbacks.

    In any case, it is a scientific inquiry.
  6. Sep 19, 2009 #5
    Not so sure about that, Patrick. https://www.amazon.com/Deniers-Renowned-Scientists-Political-Persecution/dp/0980076315 whom I know, do not attempt to deny basic statistical physical principles. It would be rather foolish to ignore physical processes either way. Or could it be that repeated strawman arguments from the remorseless propaganda have rooted deeply to give that impression?

    There are basically three things that need to be separated,

    First of all the political fallacatic implication that any position on climate should translate to a position on energy issues. It's not. I bought the world recordholder gas mileage car for that reason. But if you make that implication, it also means that, if 'global warming' is falsified that it would also give the impression that energy considerations are also falsified. Try to stop that, for one, if a new little ice age would start.

    Second, if global warming was to be true, why do we think that it would lead to catastrophies? There are several indications that nature and mankind benefitted significantly from mild climate conditions, to begin with the PETM (Paleocene Eocene Thermal Maximum), 55.3 million years ago, giving an explosion of new species, conquering the world, and more recently the Holocene Thermal Maximum, ca 9000-5000 years ago. This can be attributed to Earth insolation cycles, but it's also when the early civilisations started to prosper and devellop. Also the Medieval warm period around 800-1000AD marked the end of the dark ages in which west Europe civilisation had a huge downfall.

    Third, the physics itself. I don't think that there are many arguments against a basic climate sensitivity of about one degree celsius per doubling CO2. The main dispute is about the accumulations of all feedbacks to be positive or negative. It's a bit hard to model all that and 'retrodict' the assumed the climate cycles of the recent geologic past with that, either with positive or negative feedback. That's what the discussion should be about.
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  7. Sep 19, 2009 #6


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    With a tiny handful of exceptions, almost everything ever published that has given constraints on sensitivity has been in the range of about 1.5 to 4.5 degrees celcius per doubling.

    The point of being able to argue another side is I presume to show that you are at least aware of the other side!

    A good overview of the state of play with respect to sensitivity is available in thread [thread=334005]A low likelihood for high climate sensitivity[/thread]. The papers discussed in that thread -- Annan and Hargreaves (2006, and 2009) and Roe and Baker (2007) -- are particularly useful because they pull together conclusions based on many independent published estimates. (And just to be clear; the usual meaning of "high sensitivity", and the meaning used in all the various papers used in that thread, is sensitivity above 4.5 or so. Roe and Baker argue that it is hard to rule out such high values. Annan and Hargreaves argue that you can rule out such high values, with strong confidence.)

    If people are interested in what scientific debate looks like, there's a very relevant example in [post=2195419]msg #47[/post] of thread "Estimating the impact of CO2 on global mean temperature". This deals with a very low sensitivity estimate made by Schwartz in 2007, giving the likely range of possible values as 0.6 to 1.6. There were a number of responses published in the same journal, and then Schwartz acknowledged the corrections, and revised his estimate to the range 0.9 to 2.9, which is still low, but a bit more reasonable.

    That's what a real scientific debate looks like. People don't just argue for something they don't agree with! Rather they look into counter arguments and try to understand them. Frequently this involves being able to show where the argument is actually incorrect, on its own merits. THAT'S the real sign of science at work. It's not about seeing the other side in the sense of recognizing it and making it part of your own position, but about being able to look at the other side directly on its merits.

    The "trench warfare" distinction is not so much about holding to a particular view. Scientists do that with vengeance! It's about engaging directly with criticism. Where debate ceases to be scientific is where one side or the other simply repeats the same talking points endlessly without dealing with direct refutations. If you CAN deal with refutations, then there's nothing unscientific about continuing to hold a firm line.

    Cheers -- sylas
    Last edited: Sep 19, 2009
  8. Sep 19, 2009 #7


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    Ok, let's go.

    Partly true, but actually, it doesn't matter in the scientific debate. The *societal consequences* of one or other outcome of the global warming debate have, in them selves, not the slightest impact on the scientific debate itself. Actually, I'm not even much interested in it (I only take on the stance there when I discuss with the Green Brigade, because it's an argument they cannot counter). However, if severe global warming turns out to be not totally improbable, one has to take into account its risk. If the (bayesian) probability of severe global warming is, say, 3%, that means that one still has a risk of 0.03 times the consequence of this global warming, so this might still inspire to get away from fossil fuels earlier than on a purely economic motivation. But all of this is NOT part of the scientific debate over global warming.

    In other words, the discussion about whether there is global warming or not has nothing to do with its eventual consequences. I think that's the first thing to agree upon. It is not because an illness is severe or not, that this changes the diagnosis.

    Again, that doesn't really matter in the discussion. It's part of the earlier stance. Whatever the consequences, they don't influence the inquiry. But there's no waterproof guarantee that warming will necessarily be positive *everywhere*. Those in power (we), might be on the negative receiving end, and we wouldn't like that. That wouldn't compensate by others having better living conditions if ours get worse. It is in general, why we don't like unplanned change.

    Indeed. But that's a matter of quantitative inquiry, because we balance a lot of things, some badly understood. It is a matter of sufficient accuracy. But even 1 degree is, in my book, "climate change". Even 0.5 degree. All the rest is a matter of quantitative accuracy, but not of principle.

    Even someone accepting the possibility of 0.5 degree of systematic warming is, in my book, someone who accepts "climate change". To me, a "denier" is someone who thinks that it is utmost impossible that human CO2 exhaust can have *any noticeable influence whatever* on the climate system - meaning it should be below the level of measurement accuracy (which I take, arbitrarily, to be of the order of 0.1 degree).

    Indeed. But it is a matter of quantitative modeling now. We're outside of the "deniers-heaters" debate. We're accepting that climate change is there, and we're trying to calculate how much.

    However, the paleoclimate is just a testcase, and I don't know how much it is pertinent. What should eventually be done, is predictions "from first principles" alone, with sufficient accuracy and confidence, that it includes all of the relevant dynamics. The observations are then just secundary, as an eventual test case.
  9. Sep 19, 2009 #8
    Well it all boils down to how the perception of the public is shaped:

    For instance:

    or 'translated' to the perception:

    1: We are causing global warming.

    Probably, but so are a number of other factors, the weight of which we only begin to perceive, if at all. So is whatever we do, comparable to the weight of other factors?

    2: if we don't do anything, then it could lead to catastrophes

    and that does make reference to paleoclimate significant. There is no evidence whatsoever from the paleo records for catastrophes associated with warming for whatever reasons or would we know if the negative elements (more ocean) outweights the advantages (more biomass, milder climates in large parts of the world (like Siberia perhaps)

    3: If we stop emitting, we can deal with the problem

    Can we? Is it a problem? We have not determined how much antropogene activities contribute, so how can we conclude that stopping emission would "save the climate".

    Just for counter indication: suppose that we are heading for a new (little) Ice Age, would extra emission prevent catastrophic global cooling?

    If we need to stop emitting CO2, then why not for the sake of fully legimate reasons, like economical necessity, energy surety and security, etc.
    Last edited: Sep 19, 2009
  10. Sep 19, 2009 #9
    I was arguing about a basic sensitivity for doubling, not for the assumptions for a final sensitivity including feedbacks.

    Let's grab that envelope again and do some very basic calculations.

    If the average global temperature is 15C or 288K then according to Stefan Bolzmann for a 'black body' this translates to an equivalent black body irridiance ~389.9 w/m2.

    Now if we would double CO2 we assume an increase of the irridiance with what? 3.7 w/m2? or 5 w/m2 or 10 w/m2 to resp ~393.6 or ~394,.9 or 399.9 w/m^2. This would correspond to temperature rises of 0.7K or 0.9K or 1.8K respectively (assuming 100% absorption). I hear 3.7 w/m2 a lot, so 1.0K does not seem too odd as simple basic value. The question remains if there is enough positive feedback to boost radiation to double orders of magnitude.
    Last edited: Sep 19, 2009
  11. Sep 19, 2009 #10


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    OK, I understand you now. I think this is more usually called "Planck response", or "base response". Since this is what you are speaking of, I concur.

    The Planck response, or base response is roughly 1 -- or if we are more precise it is around 1.12 to 1.16. The simple blackbody estimate will get into the ballpark okay; a more careful account is given with references in the latter part of [post=2318289]msg #171[/post] of thread "Need Help: Can You Model CO2 as a Greenhouse Gas (Or is This Just Wishful Thinking?)".

    It turns out that you can get into the ball park more closely using 4Q/T where Q is the emission from Earth (about 240 W/m2) and T is the mean surface temperature (about 288K). (The Planck response of a simple blackbody with the same emission to space as the Earth would use T as 255K, being the mean emission temperature.) This gives 0.3 K/(Wm-2). Converting units this is 1.11 K/2xCO2, with 2xCO2 being 3.71 Wm-2, as you also note.

    Cheers -- sylas
    Last edited: Sep 19, 2009
  12. Sep 19, 2009 #11


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    If you translate this into: our actions give/will give rise to a measurable higher temperature than it would be without them, I think that is the essence of the discussion. Whether this is the MAIN cause of change is another issue: for sure a gigantic volcano eruption, or the impact of a meteorite, or other things of the kind, are always possible.

    What the discussion is about is whether the change is noticeable. Whether it will be warmer with than without.

    Again, that's not part of any scientific debate by itself.

    Ok, but there hasn't been a technological and economical society like there is one today either. So the impact on global economy is not to be read from these paleo observations.
    The question is whether it will have a negative economic impact on the economic powers that be. Will global warming have a positive or negative impact on the tourism in the south of Spain, for instance ? You can't find anything out like that using paleo data. Will potential climate change be beneficial for the Bourgogne winegards ? It will probably be negative, because in order to continue to make the wine they make now, they need as small a change in parameters as possible.

    But again, that's not part of the scientific discussion, at all.

    You shouldn't think - in the scientific debate - about climate change as a "problem", but just as an "outcome". So the answer here is: if we stop emitting now, will this significantly alter the effect as compared to if we don't stop emitting, or even emit more ?

    Again, this is a matter of quantitative accuracy, but I would think that the answer if fairly obvious, no ? It will make a numerically significant difference. You will be able, instrumentally, to distinguish between both.

    But, in the scientific debate about climate change, there's nothing we should or shouldn't do. There's just the question of how much, in what circumstances. Whether this is "good" or "bad" and whether we should encourage it or avoid it, is not a scientific debate. It should be totally separated from it.

    What's "good" and what's "bad" depends on one's PoV and hence is not scientifically debatable.

    For fun: http://en.cop15.dk/news/view+news?newsid=2099

    Greenland wants to emit more CO2. One can understand them :smile:
    (ok, they don't openly say they want the world to heat, but I'm sure they don't lie awake from it...)

    So again, the *effect* of fossil fuels and other human-made greenhouse gasses on the climate is a scientific matter, which stands in no relation to how one should react to it. The effect is independent of whether it is desirable or undesirable. And that's where the discussion is about.
  13. Sep 19, 2009 #12

    In the past civilization flourished during the warm periods. There was starvation during the cold periods. Air holds roughly 6% more water for each 1C it is warmer. 70% of the planet is covered with water. When the planet is warm there is ample rain, the biosphere expands. When the planet is cold, it is windy and dry, the biosphere contracts. At 200 ppm C3 plants stop growing. As CO2 increases C3 and C4 plants require less water and make more effective use of sunlight. CO2 is added (2000 to 3000 ppm) to greenhouses to increase yield and reduce time to yield.

    It appears based on the science (measurement of upper atmosphere temperatures shows the current planetary warming was not caused by GWG.) that the atmosphere saturates with respect to additional CO2. There have been periods of planetary glaciation when CO2 levels were as high as 2000 ppm. CO2 does not correlate with planetary temperature in the geological past.

    It appears the planet is about to abruptly cool not warm. There is are hundreds cycles of long term abrupt planetary cooling events that correlate with cosmogenic isotope changes (Traced out until 1 million years ago which is the limit of the paleo record). The cosmogenic isotope changes occur due to solar magnetic cycle changes which increases the amount of galactic cosmic rays (GCR, mostly high speed protons) that strike the earth's atmosphere.

    The GCR create muons which in turn create ions in the atmosphere. More ions more planetary cloud cover. Particularly over the ocean which is ion poor. Rain removes ions so unless the ions are replenished cloud formation is abated.



    GCR levels have increased 18%, however cloud cover has not as yet increased.

    There is a second mechanism by which the sun modulates planetary cloud cover, electroscavenging. Solar wind bursts create a space charge in the ionosphere which removes ions by a process called electroscavenging.

    The 20th century warming was caused by electroscavenging. The solar wind bursts in addition to removing ions from the atmosphere disturb the geomagnetic field. Ak is a measurement of the amount of disturbance of the geomagnetic field and the time delay of the effects of the solar wind bursts.

    There is direct correlation of the complete 20th century warming with Ak.



    If the Sun is so quiet, why is the Earth ringing? A comparison of two solar minimum intervals.
    Last edited: Sep 19, 2009
  14. Sep 19, 2009 #13

    Once again about global warming and solar activity K. Georgieva, C. Bianchi, and B. Kirov

    See section 5a) Modulation of the global circuit in this review paper, by solar wind burst and the process electroscavenging where by increases in the global electric circuit remove cloud forming ions.

    The same review paper summarizes the data that does show correlation between low level clouds and GCR.

    http://www.utdallas.edu/physics/pdf/Atmos_060302.pdf [Broken]
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  15. Sep 19, 2009 #14


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    BLAM. There goes my irony meter.

    Saul: the topic of this thread is NOT an invitation for you to just make all the same claims you have habitually made in the past. It is in fact precisely the reverse. It's about how capable people are of understanding the position they DON'T hold, as shown by their ability to make the arguments as they would be made by their opponents.

    I'm not persuaded that this is all that useful an exercise as phrased; but I do take the point that scientific debate works by engaging substantively with counter positions from a position of understanding. Other contributors here are all taking up the matter of the nature of the scientific debate in general terms.

    By just jumping in to restate your own perspective on a climate related topic, you've completely missed the whole point.
  16. Sep 19, 2009 #15

    http://geology.about.com/od/extinction/a/aa_permotrias.htm" [Broken]
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  17. Sep 19, 2009 #16

    Unfortunately the planet is about to abruptly cool. The beneficial warming is over.

    This is not a surprise. Interglacial periods have all end abruptly. There is evidence in the paleoclimatic record of a cyclic massive external forcing function. There are dozens of published papers that outline specifically what that forcing function is.

    This is a scientific discussion not a moral discussion. We are not going to solve the problem of abrupt planetary cooling by reducing anthropic produced CO2. Anthropic CO2 is one of the few beneficial changes humans are making to the biosphere.

    Think of the irony of eminent abrupt planetary cooling, after decades of discussions about abrupt planetary warming.

    This is of course why there are scientific revolutions. Have you read Thomas Kuhn's "The Structure of Scientific Revolutions". The AWG movement is an example of group think. When people have a position they continue to maintain that position even when the facts no longer support that position.

    If there was not a glacial/interglacial cycle, cyclic abrupt climate change that correlates with cosmogenic isotope changes, lack of correlation of CO2 levels with planetary temperature in the geological past, a mechanism by which solar magnetic cycle changes affect planetary cloud cover and the geomagnetic field, evidence of cyclic geomagnetic field changes which also correlate with solar magnetic cycle changes, past civilization collapse during abrupt cooling events, the AWG "position" might be theoretically defensible.


  18. Sep 19, 2009 #17
    Right, it must have been pretty hot when a large part of Siberia erupted in what is known as the largest volcanic event on record, http://www.solcomhouse.com/siberiantraps.htm [Broken]

    http://www.solcomhouse.com/images/SiberiaAmphiboleFig2_550.gif [Broken]

    See also this and this

    Note that the CO2 release and warming is a proposal not supported by direct evidence. Compare this with the prospect of other very tiny mini volcanic eruptions like Yellowstone, and the projected direct causalities. The Siberian traps could just as well have released enough chemicals for direct poisening effects.
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  19. Sep 19, 2009 #18
    It is interesting to me that this board seems to be dominated by those who (assuming the media and government hasn't lied to me) hold a minority position.
  20. Sep 19, 2009 #19


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    They're all just kidding, of course. You are seeing the consummate example of the whole principle of this thread.

    Cheers -- Sylas -- who is of course secretly laughing up his sleeve and has massive investments in a proposed ski resort just out of San Diego.
  21. Sep 19, 2009 #20
    So if the numbers make the difference, what, for instance, would be the score on evolution science versus creation believers? And what would that say about scientific merit?

    Maybe that the first law of science is not to jump on bandwagons.

    Anyway, this thread used to be about the real numbers. However, it seems to be modified a bit.
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