Global Warming and the Role of Models in Science

 

shutterstock_111084638Having been introduced to Ricochet on the wonderful National Review cruise, I would like to make my inaugural contribution about ‘climate science’. To begin with, let me say that I am a physicist and, though I have looked into the question of global warming a little bit in the past, I am certainly no ‘climate scientist’. In fact, this term is in any case misleading, I think, because the climate is a very diverse subject and it is quite impossible to be an ‘expert’ on every aspect of it. An expert on tree rings is not likely to be an expert on the physics of cloud formation as well. Needless to say, I am neither.

It is in fact with some reluctance that I write about this topic, because it is a political distraction. The scientific foundation is obviously far too uncertain to be a basis for taking any drastic action with deleterious economic consequences. In fact, ‘global warming’ seems to have paused, but even if this were not the case it is not clear that a small increase in average temperatures would not overall be more beneficial than harmful. And even if it had not stalled and it were more harmful than beneficial, then drastic action might well still be inadvisable because deteriorating economic conditions would make it more difficult to deal with any harmful effects.

A healthy dose of skepticism is apposite. The global warming scare clearly suits the Left, because they embrace world-wide action and international organizations. Moreover, it distracts from the avalanche of bad news they are facing currently. It is therefore probably unwise to engage in arguments with them about it at all. They are too comfortable in their beliefs to be open to debate.

At the same time, I sometimes hear arguments like: The amount of carbon dioxide in the atmosphere is a tiny fraction, so that cannot possibly make a difference. This is wrong, and it is therefore perhaps useful to explain why.

In early 2009, I became interested in models for global warming after reading about the hockey stick controversy. It seemed to me that it was convincingly shown by McIntyre and McKitrick that this work was erroneous, so it irritated me that Nature never retracted the hockey stick paper. The other main pillar of global warming theory seemed to be computer models. The assumptions that go into such models intrigued me. Unfortunately, the actual computer algorithms are difficult to get hold of, so I decided to try something simple myself. At this point it is useful to explain the role of models in science in general.

From grand scientific theories like the theory of relativity, quantum mechanics and evolution theory one may get the impression that scientific models are precise and detailed. This is a misunderstanding. Most models of physical systems are, on the contrary, quite deliberately caricatures. The art of constructing a model is to isolate the relevant features of a system for explaining a particular phenomenon, while ignoring various other characteristics that are not significant for that phenomenon. For example, in order to understand why iron can be magnetized (this is called ferromagnetism), one does not describe the state of all iron atoms in an iron bar in detail, but singles out the interaction (forces) between single electrons in each atom and, moreover, simplifies this interaction to a manageable form.

This may be somewhat abstract, so here is another, more easily understood example. Consider an object falling from a height. According to Newton’s laws, its speed increases linearly in time, because it moves in an essentially constant gravitational field. (In fact, this is already an idealization, because the field strength decreases with height.) Moreover, as Galileo showed, the speed is independent of the mass (weight) of the object.

Actually, this a bad model. We all know that a feather falls more slowly than a lead ball. One needs to take air resistance into account. Einstein already said: a model should be as simple as possible, but no simpler. An approximate way to take air friction into account is to assume that the friction force is proportional (but opposite) to the velocity. With this assumption, one finds that the speed approaches a constant value. This is the principle of a parachute: if the friction is large enough, the final velocity remains small enough so that one can survive the fall.

Notice that this simple assumption about the friction force is a caricature: the actual friction force will depend on the precise shape and movement of the object, and its dependence on the velocity is also, in general, more complicated. Nevertheless, this model is quite useful in many circumstances and has the advantage of simplicity: there are few adjustable parameters. The more parameters, the less predictive power a model has.

Coming back to global warming, I decided to construct as simple a model as possible describing the effect of carbon dioxide on the global atmospheric temperature. Is it even reasonable to assume that a trace gas can have a significant effect on the average temperature? In fact, this in not unreasonable (and of course, it is already a very old idea). It is essentially due to resonance.

When a column of soldiers crosses a bridge, they are told not to march in step, because their regular marching step could be in resonance with a particular characteristic frequency of the bridge, causing it to swing wildly. Similarly, molecules of particular gases have (bands of) special characteristic frequencies. If they are radiated with (infrared) light of such a frequency they start vibrating, thus absorbing energy from the radiation.

The Earth’s surface radiates approximately as a black body, i.e. its radiation varies in strength (intensity) with the frequency, with a maximum in the infrared. Some of this radiation is in resonance with water molecules, which are abundant enough so that the absorption is mostly saturated for those frequencies. However, two of the three absorption bands of carbon dioxide lie outside those of water. In particular, the main band is not entirely saturated at the edges. This means that increasing the amount of carbon dioxide in the atmosphere will increase the absorption in the edge of the band.

One can show that this follows a square-root law. Adjusting the constant in front of the square root, one can get reasonable agreement with the observed global warming from 1880 until 2008. (There are, of course, large fluctuations on top.) At the time, I tentatively concluded that this might be a sensible model, dismissing the reported recent leveling-off as a short-term fluctuation. However, it is essential for scientists to be honest in assessing their theories. It seems that this period of stable temperatures has now lasted for some 15 years and looks less and less like a short-term effect. The model is therefore inadequate. Some relevant variable has been omitted.

At this stage, it is perhaps appropriate to make a remark about these temperature measurements. At first sight it might seem like a straightforward exercise to measure temperature. Thermometers are certainly very accurate, but they only measure a local temperature. To obtain the average temperature of the Earth’s surface, once has to perform an average — and it is far from clear how this should be done. Obviously, the thermometers are not distributed evenly over the Earth’s surface, so one has to give some a higher weight than others. This makes the highest-weight thermometers most significant and faulty operation or placement of these will have proportionately greater effect. Notice that these are likely to be the ones in the most inhospitable places and therefore more susceptible to faults.

The distribution of carbon dioxide in the atmosphere is in fact very uniform so the effect should be felt everywhere (though perhaps not to equal extent). As long as the distribution of thermometers is unchanged, one might hope that the precise method of averaging is not important provided that the temperature increase is significant and observed in most places. By the way, the term ‘global warming’ is a sensible name for this supposed phenomenon. ‘Climate change’ is an obfuscation because the climate changes due to other effects. Indeed, these are also still poorly understood, but may be supposed to happen on longer time-scales (although this is far from certain).

Coming back to the model, there are obviously many possible causes for the halting temperature increase: for example increased cloud formation, increased vegetation, volcanic activity, or solar activity. Some of these are back-reactions similar to the friction in the example above and could conceivably lead to a leveling-off. Incorporating them in the model is not easy, however. Perhaps some of these are incorporated in the complicated ‘general circulation models’ used, but these did not seem to predict the leveling-off of the global temperature, so this is hardly convincing.

A few more remarks about the science. Some of the carbon dioxide is absorbed in the oceans. Because the partial pressure of CO2 is low, the absorption is not large and because carbonic acid is a weak acid, it seems to me that acidification of the oceans due to this effect is insignificant.

Another consequence of global warming would be rising sea levels. As in the case of measurements of the global temperature, measuring the average sea level is not straightforward: it is a very small effect superimposed on large fluctuations. Nevertheless, measurements seem to show that there is a systematic effect amounting to roughly 2 millimeters per year. This is hardly something to worry about in the foreseeable future. Moreover, a rough calculation shows that it agrees with the thermal expansion resulting from the observed temperature increase. With the global temperature seemingly having stabilized, this should also level off, but I am not au fait with recent measurements.

I apologize for the length of this piece but I hope it serves the purpose of illustrating how a skeptical scientist might think about this topic. By the way, contrary to how it is often portrayed, I am by no means the only skeptical scientist, and in any case, scientific facts are not established by majority vote. Indeed, it is often dissenters who show the way forward.

 

 

 

 

 

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  1. skipsul Inactive
    skipsul
    @skipsul

    Welcome to Ricochet and thanks for the post.  We’re always glad to get more scientists and engineers here.

    Your post reminds me of an old joke though, heard in many variants.

    You ask a physicist “Why did the chicken cross the road?”  The response being “Well, first you assume a perfect sphere…”

    • #1
  2. user_1030767 Inactive
    user_1030767
    @TheQuestion

    Welcome to Ricochet, and thank you for this.  I’m going to need more time to go through this, although on the parts I have digested I agree with you.  I’ve taught college environmental science, and I hesitate to approach this topic for a number of reasons.

    It’s definitely a mistake to call global warming a “hoax,” as Richard Epstein says in his recent Libertarian podcast.  An example of a hoax would be Piltdown Man, where ape specimens were taken from a museum collection and presented as fossils dug up in England.  That’s a hoax.  The warming trend in the 20th century was real, as you point out.  What conclusions are to be drawn from that observation are another matter.  When Jim Inhofe calls global warming a hoax, it gives the Democrats an opportunity to make legitimate points, which we shouldn’t be allowing them.  It might be fair to say that the effectiveness of the policies presented by Democrats to address global warming is a hoax, but I don’t think that’s how people are hearing Jim Inhofe.

    At some point, I’d like to do what you have done and seriously research the primary literature on global warming and form my own professional, educated position.

    • #2
  3. user_1030767 Inactive
    user_1030767
    @TheQuestion

    One thing I forgot to ask: one response to the warming hiatus of the 21st century is that while the atmosphere is not warming, the oceans are.  What do you think about this argument?

    • #3
  4. Majestyk Contributor
    Majestyk
    @Majestyk

    Ah, finally the person that I wanted to talk to.

    I too am curious about the models that have been used to trump up the charges regarding Global Warming/Climate Change and the underlying assumptions that have been made to justify disastrous policy recommendations.

    As an Engineer, I tried to boil the problem down to its simplest elements.  The Earth’s surface and climate has 3 primary sources of energy input: The Sun, Cosmic rays and internal heating from the planet’s core.  Simple math will eliminate two of these as essentially trivial.

    The problem then boils down to one of a simple energy balance.  The Earth loses heat (as you’ve said) via radiative losses as if it were a blackbody object according to the Steffan-Boltzman equation.  However, I lack the sophistication to accurately model the upper reaches of the atmosphere to see how much energy the planet loses.

    I started with the mass of the atmosphere and the total mass of the oceans, figured out their heat capacities (ignoring the planet’s core and crust) and saw how much energy it takes to warm them up by a single degree and compared it to net solar irradiance to see how long it would reasonably take to net that much energy and see if that compared favorably to the additional energy the planet would lose from blackbody radiation to space as a result of that increase in temperature.

    The results (of treating the approximate surface of the atmosphere as as Sphere) informed me that it is extremely difficult to warm the planet, because the Steffan-Boltzman equation operates as a function of the Fourth Power of absolute temperature – so increasing the mean surface temperature of the Earth by a single degree K increases the radiative losses by 1.4%.

    You have to capture a lot of solar radiation to accomplish this, even given the CO2 energy absorption, which just leads to higher radiative losses in the atmosphere.

    So, the conclusion I reached is that the atmosphere is (mostly) in a static equilibrium, and it is forced to be in that state by the fact of higher energy losses at higher temperatures, so the equilibrium quickly reestablishes itself.

    Where am I going wrong?

    • #4
  5. Mike H Coolidge
    Mike H
    @MikeH

    Welcome fellow physicist! I didn’t quite make it through your whole article, but I like what I saw and I think it will be informative for a lot of people… now back to thesis writing!

    • #5
  6. Z in MT Member
    Z in MT
    @ZinMT

    Majestyk:Ah, finally the person that I wanted to talk to.

    I too am curious about the models that have been used to trump up the charges regarding Global Warming/Climate Change and the underlying assumptions that have been made to justify disastrous policy recommendations.

    As an Engineer, I tried to boil the problem down to its simplest elements. The Earth’s surface and climate has 3 primary sources of energy input: The Sun, Cosmic rays and internal heating from the planet’s core. Simple math will eliminate two of these as essentially trivial.

    The problem then boils down to one of a simple energy balance. The Earth loses heat (as you’ve said) via radiative losses as if it were a blackbody object according to the Steffan-Boltzman equation. However, I lack the sophistication to accurately model the upper reaches of the atmosphere to see how much energy the planet loses.

    I started with the mass of the atmosphere and the total mass of the oceans, figured out their heat capacities (ignoring the planet’s core and crust) and saw how much energy it takes to warm them up by a single degree and compared it to net solar irradiance to see how long it would reasonably take to net that much energy and see if that compared favorably to the additional energy the planet would lose from blackbody radiation to space as a result of that increase in temperature.

    The results (of treating the approximate surface of the atmosphere as as Sphere) informed me that it is extremely difficult to warm the planet, because the Steffan-Boltzman equation operates as a function of the Fourth Power of absolute temperature – so increasing the mean surface temperature of the Earth by a single degree K increases the radiative losses by 1.4%.

    You have to capture a lot of solar radiation to accomplish this, even given the CO2 energy absorption, which just leads to higher radiative losses in the atmosphere.

    So, the conclusion I reached is that the atmosphere is (mostly) in a static equilibrium, and it is forced to be in that state by the fact of higher energy losses at higher temperatures, so the equilibrium quickly reestablishes itself.

    Where am I going wrong?

    I think your analysis is largely correct if the Earth and the atmosphere could be modeled as perfect black bodies.  The problem is that the albedo (somewhat like the refelctivity) of the earth is highly variable.  This why the models diverge so much.  If you assume that albedo doesn’t change in response to CO2 then you get very little change in surface temperatures, however depending on what you assume the response of the clouds are the change in albedo can be correlated or anti-correlated with temperatures. At this point we don’t understand cloud formation well enough to make any predictions vis a vis global warming.  In the end, I am in the camp that if the earth atmospheric system were as unstable as the global warming alarmists would have us believe that life on earth would not have survived until now.

    • #6
  7. Tuck Inactive
    Tuck
    @Tuck

    Great post, thanks for making it.

    Michael Sanregret: It’s definitely a mistake to call global warming a “hoax,” as Richard Epstein says in his recent Libertarian podcast.

    “Global warming” as you define it, is not a hoax.  But most folks use it as shorthand for Anthropogenic (man-caused) Global Warming, which is clearly a hoax.

    One of the things I’ve looked into professionally is financial fraud detection.  There are a couple of hallmarks of financial fraud—rules of thumb from looking at the raw data that indicate a fraud is likely taking place.  One of these rules of thumb is that supposedly “neutral” adjustments should have a normal distribution: equal amounts are positive versus negative.

    The raw data for AGW has mostly been destroyed, but those datasets that still exist can be compared with the “adjustments” that scientists make.  The global warming signals for the 20th century only exist in the adjustments.  And those adjustments are not normally distributed.

    rutherglen_station_plot_raw_homogenized[1]

    • #7
  8. Mike H Coolidge
    Mike H
    @MikeH

    Tuck: “Global warming” as you define it, is not a hoax.  But most folks use it as shorthand for Anthropogenic (man-caused) Global Warming, which is clearly a hoax.

    Not exactly, the “hoax” is actually Catastrophic Anthropogenic Global Warming.  It’s very likely at least some of the warming is due to human endeavors. My money is on the sun being the most important climate driver and we’re in the process of entering a mid-century mini ice age.

    • #8
  9. Spin Coolidge
    Spin
    @Spin

    Welcome to Ricochet.  By joining and, more importantly, egnaging, you make it even smarter a place than it already is.  For my part, I ahve the opposite effect, as can be described in my recent model, which I developed in Microsoft Word.

    That aside, can you describe for the audience what, exactly, a physicist does?  Do you research stuff?  Teach?  Play video games?  What is it that you get paid for?  I mean this seriously.  I’m curious.

    • #9
  10. Majestyk Contributor
    Majestyk
    @Majestyk

    Z in MT:

    The problem is that the albedo (somewhat like the refelctivity) of the earth is highly variable. This why the models diverge so much. If you assume that albedo doesn’t change in response to CO2 then you get very little change in surface temperatures, however depending on what you assume the response of the clouds are the change in albedo can be correlated or anti-correlated with temperatures.

    The variability of albedo as a result of CO2 is noise in the signal in comparison to cloud cover.  Even if the Earth’s average albedo increased as a result of increased CO2 concentration, additional offsetting factors such as increased cloud cover from increased water vapor would likely override that small increase, however temporarily.

    This is actually an argument in my opinion in favor of climate becoming slightly more volatile because of competing cycles of offsetting variables but again, this is noise within the signal only – not a long term destructive and irreversible trend.

    • #10
  11. virgil15marlow@yahoo.com Member
    virgil15marlow@yahoo.com
    @Manny

    I’m a mechanical engineer and we use models to do all sorts of predicting mechanical behavior.  When I first heard that global warming was based on models I knew it was all bogus.  Mechanical behavior of metal parts can be predictably modeled, and even then it’s got a fair amount of error.  When it comes to something as complex as the atmosphere that is based on fluid and gas behavior I knew they were either fudging the numbers or deluding themselves.  If mechanical behavior can’t be modeled to a couple of percent accuracy, how could they model temperature, fluid, gas, and all the radiation effects from outer space to predict to a fraction of a celcius degree?  Baloney, and the lack of being able to predict for the last ten years has shown it.  They are frauds.

    By the way, welcome. :)

    • #11
  12. Tuck Inactive
    Tuck
    @Tuck

    Mike H: It’s very likely at least some of the warming is due to human endeavors.

    Not really.  First off, what warming?

    All the raw data sets I’ve looked at show no warming to slightly declining temps over the 20th century.  The warmest period was likely the early 20th century—that’s the time period that’s most often adjusted down, as in the example I gave.  And even if you agree with the reported warming, it is within any reasonable margin of error.  As likely noise as signal.

    The mass release of CO2 that’s supposed to cause AGW occurred in the latter part of the 20th century.

    The bulk of the recent warming seems to have occurred in the 19th century (the end of the Little Ice Age).  That’s long before mass CO2 release started.

    So the argument that CO2 is responsible for this supposed AGW has some big holes in it, to put it mildly…

    Which isn’t to say that increased CO2 couldn’t have increased temperatures, it is a greenhouse gas, after all, if a poor one.  But it doesn’t appear to have worked that way in fact.

    Then we have the problem of predicting climate.

    ““The forecasters look at lots of different models: Euro, Canadian, our model — there’s models all over the place, and they don’t tell the same story,” Ben Kyger, a director of operations for the National Oceanic and Atmospheric Administration, told me. “Which means they’re all basically wrong.””

    And those are just the models that we use to forecast the weather tomorrow.  So it’s not surprising that increasing CO2 levels have failed to do what forecasters have predicted, it’s the expected outcome.

    “My money is on the sun being the most important climate driver and we’re in the process of entering a mid-century mini ice age.”

    That’s where my money is too.  At any rate, I’ll take Larry Niven and Jerry Pournelle’s prediction over some left-wing academics’!

    “As a new Ice Age imperils the world, a lunatic fringe of the environmental movement has taken control of the U.S. government.”

    • #12
  13. Mendel Inactive
    Mendel
    @Mendel

    Welcome to Ricochet!

    As a fellow scientist, I take a somewhat different approach.

    There are certain questions (actually an innumerable amount) in science whose complexity so dwarfs our current understanding that we have no realistic chance of reaching an accurate and well-informed answer. In other words, there are situations in which the most scientific response is to say “I haven’t a bleeping clue.” Indeed, I have heard Nobel prize winners say as much on certain topics within their field of expertise.

    The paradox I see is that most of us agree that the concept of “climate” is simply too complex to put any faith in the models or predictions proposed by the alarmists. Yet at the same time, we delve into the specifics of the issue, thereby implying that we are smart enough to distill such a complex topic into its relevant parameters. And worse, we often draw conclusions with the exact same degree of confidence as those we accuse of hubris.

    I think the only honest answer to the question of anthropogenic climate change is: nobody has a bleeping clue.

    • #13
  14. Mendel Inactive
    Mendel
    @Mendel

    Tuck:

    First off, what warming?

    All the raw data sets I’ve looked at show no warming to slightly declining temps over the 20th century.

    But how is that proof that humans are not warming the Earth above the temperature(s) it would naturally have? Perhaps the 20th century would have actually been one of significant cooling had it not been for the influence of humans.

    Without knowing what the baseline “climate” would be in the absence of humans, there’s no reasonable way to assess whether that climate is or is not changing.

    Again, I am completely agnostic on (and slightly tired of) the question of human influence on climate. All I object to is everyone else’s unjustified confidence, regardless of which direction it may tend.

    • #14
  15. Tuck Inactive
    Tuck
    @Tuck

    Mendel: But how is that proof that humans are not warming the Earth above the temperature(s) it would naturally have? Perhaps the 20th century would have actually been one of significant cooling had it not been for the influence of humans.

    Then the phrase should be “Anthropogenic Prevention of Cooling”.  If it was, we might have a discussion.  But’s it’s not.

    It’s “Anthropogenic Global Warming”, and the word warming has a distinct meaning.

    “All I object to is everyone else’s unjustified confidence, regardless of which direction it may tend.”

    It’s science, right?  They made a prediction.  Did it pan out?  I don’t see how it can be said to have…

    As an aside, there is a fellow who makes the claim you raise above.  He does not depend upon the emissions of the automobile, however…

    • #15
  16. Mendel Inactive
    Mendel
    @Mendel

    Tuck:

    Mendel: Perhaps the 20th century would have actually been one of significant cooling had it not been for the influence of humans.

    It’s “Anthropogenic Global Warming”, and the word warming has a distinct meaning.

    Actually, I would argue that the term Anthropogenic Global Warming is vague and ambiguous: does it refer to warming compared to previous temperatures or compared to what the temperature of the Earth would have been without humans? Both definitions are within the scope of the phrase.

    If anything, I would imagine most people, after thinking it over, would lean toward the second definition. And of course, most alarmists would just say “all of the above.”

    I agree that most of the public doesn’t delve into this degree of nuance. But I thought the whole idea of this thread was to address the issue with a higher degree of intelligence than is found in the general public debate.

    • #16
  17. Tuck Inactive
    Tuck
    @Tuck

    Mendel: Actually, I would argue that Anthropogenic Global Warming is vague and ambiguous: does it refer to warming compared to previous temperatures or compared to what the temperature of the Earth would have been without humans? Both definitions are within the scope of the phrase.

    I don’t think they are both within the scope of the phrase, if it’s read in context.  Warming in this case is something bad, to be stopped, before it harms the planet.

    Warming that prevented an ice age would be regarded as a good thing.

    If the latter interpretation were correct, we’d have governments increasing CO2 emissions to save the planet, not attempting to reduce them.

    • #17
  18. Mendel Inactive
    Mendel
    @Mendel

    Tuck:It’s science, right? They made a prediction. Did it pan out? I don’t see how it can be said to have…

    I mostly agree with you on the specific question (although I have little confidence in any temperature data).

    However, this individual case misses the big picture. In reality, the underlying question society wants to answer is: are humans changing the climate in such a way that our standard of living will be drastically impacted in the future?

    “Global warming” is one hypothetical answer to this question. But there are many other hypothetical mechanisms by which humans could alter the climate. The fact that the global temperature did not rise over the 20th century does not address most of these hypotheses, and thus does little to bring us closer to an answer to the underlying question.

    Indeed, I predict that as the evidence for “global warming” becomes thinner, alarmists will eventually switch back to the “climate change” slogan. But from a scientific perspective, the debate will still be far from over when that happens.

    • #18
  19. Tuck Inactive
    Tuck
    @Tuck

    Mendel: In reality, the underlying question society wants to answer is: are humans changing the climate in such a way that our standard of living will be drastically impacted in the future?

    I think if one changes “climate” to “planet” the answer is an unequivocal “Yes”.  It’s likely “Yes” already on the climate question, as there’s a good argument to make that desertification is a man-caused phenomenon.

    See the Anthropocene Extinction.  Agriculture is a reaction to that on-going event.  I’d say running out of food is a drastic impact!

    “Indeed, I predict that as the evidence for “global warming” becomes thinner, alarmists will eventually switch back to the “climate change” slogan. ”

    Yeah, they’ve already done so.  Best indicator going that the argument for AGW fell apart.

    • #19
  20. Spin Coolidge
    Spin
    @Spin

    Mendel: Again, I am completely agnostic on (and slightly tired of) the question of human influence on climate. All I object to is everyone else’s unjustified confidence, regardless of which direction it may tend.

    There certainly enough gas on this thread to warm a small planet.

    • #20
  21. Z in MT Member
    Z in MT
    @ZinMT

    Majestyk:

    Z in MT:

    The problem is that the albedo (somewhat like the refelctivity) of the earth is highly variable. This why the models diverge so much. If you assume that albedo doesn’t change in response to CO2 then you get very little change in surface temperatures, however depending on what you assume the response of the clouds are the change in albedo can be correlated or anti-correlated with temperatures.

    The variability of albedo as a result of CO2 is noise in the signal in comparison to cloud cover. Even if the Earth’s average albedo increased as a result of increased CO2 concentration, additional offsetting factors such as increased cloud cover from increased water vapor would likely override that small increase, however temporarily.

    This is actually an argument in my opinion in favor of climate becoming slightly more volatile because of competing cycles of offsetting variables but again, this is noise within the signal only – not a long term destructive and irreversible trend.

    I think I largely agree with you.  But it is by making assumptions about the effect the small increase in temperature caused by CO2 has on water vapor, that so called climate scientists come up with models that predict catastrophic global warming.  My point is similar to Mendel’s “we don’t have a bleeping clue.”  Also my best evidence that anthropogenic global warming (AGW) isn’t science is that if you tell me who a scientist voted for in the last election I can predict with great accuracy his opinion on AGW.

    I am a physicist.  Every conservative scientist\engineer  I know is skeptical of AGW, whereas every liberal scientist\engineer I know (a much larger cohort) buys AGW hook, line, and sinker.

    • #21
  22. Z in MT Member
    Z in MT
    @ZinMT

    The story of global warming is very logical and backed up by incontrovertible facts. Unfortunately it doesn’t necessarily make it true.

    Incontrovertible Fact 1:  The CO2 fraction in the atmosphere has been recorded for more than 50 years now and the increase from 300 ppm to 400 ppm during that time is large.  A back of the envelope calculation on industrial and transportation CO2 emissions matches this increase nicely (in fact more detailed calculations show the CO2 concentration has increased slightly more than expected from man-made sources).

    Incontrovertible Fact 2: CO2 is a greenhouse gas in that it transmits visible light and absorbs infrared light which is emitted by the blackbody of the earth.

    Conclusion: Therefore, the large increase in CO2 in the atmosphere will cause the lower troposphere temperatures to increase.

    If that is all you know, and an expert tells you that his model predicts the temperature increase will be dire, it is easy to stop there and not investigate any further.

    This why AGW has gotten so much traction.  To explain why this won’t happen requires much further explanation and refutation of the models, which requires more sophisticated analysis.

    • #22
  23. user_1030767 Inactive
    user_1030767
    @TheQuestion

    When I was in grad school in the 1990s, I was convinced by the evidence that there was a real warming trend going on.  One of the points of evidence for this was changing migration patterns in birds (e.g. birds migration ranges were shifting north in response to rising temperature).  As far as I know those changing migration patterns haven’t been refuted.  Of course, that doesn’t prove that global warming is catastrophic or anthropogenic.  That was also before the warming hiatus started.  I wish I had the time or money to really study all that has been published on this.

    When people talk about experimental proof, that usually implies replication and preferably some kind of experimental manipulation.  You can’t do experimental global ecology when we’ve only got one globe to study.  That doesn’t prove that catastrophic anthropogenic global warming isn’t happening, but I think the certainty they claim is what might be described as a hoax, although I think hubris is probably more apt.

    • #23
  24. user_1030767 Inactive
    user_1030767
    @TheQuestion

    Z in MT: In the end, I am in the camp that if the earth atmospheric system were as unstable as the global warming alarmists would have us believe that life on earth would not have survived until now.

    That’s my intuition as well.  I think we humans need to think about how to keep the Earth livable for humans, but I think the effect we have on the Earth in the scale of geological time is not going to be anything out of the ordinary.

    • #24
  25. iWc Coolidge
    iWc
    @iWe

    Here is the most important summary I know of:CMIP5-90-models-global-Tsfc-vs-obs-thru-2013

    • #25
  26. user_836033 Member
    user_836033
    @WBob

    I agree that cooling is the real threat.  It’s odd that no climate scientist would deny that we are nearing the end of an interglacial period, during which all of recorded human history has occurred.  And yet even with this unanimity, so many of them fret about warming.  It seems that given the undeniable fact of the approaching end of civilization due to ice, we would all agree that anything we can do to heat the planet up, we should be doing.

    • #26

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