What's wrong with a bit of global warming?

[vanesch]

How c.. -sure are we that aether does not exist, or phlogiston? Isn't science all about eliminating options that proved to be wrong? The IPCC has done predictions of which we are witnessing how (in)-correct those are. Model predicted radiation fingerprints were proven wrong with factual data (see Miskolsczi's greenhouse thread).

Yes, and now models are proposed that correct for this. I agree that post-false-prediction-corrections-to-make-them-fit is often the beginning of the end, but the *actual* prediction, which is that upon CO2 doubling, we will get between what is it, 1.5 and 6 degrees average global warming in about 100 years, has not been falsified yet, for the simple reason that we haven't been waiting yet for 100 years.
In complex modeling, it can happen that the finer details are wrong. This can indicate that the whole thing is misguided. It can also indicate that the general idea is right, but that the finer details are not understood.

I still take it as not entirely proven beyond reasonable doubt that a significant CO2 change is totally neutral concerning temperatures in 100 years from now.

 

[Andre]

Yes, and now models are proposed that correct for this. I agree that post-false-prediction-corrections-to-make-them-fit is often the beginning of the end,

Now where did I read that before? Ah http://www.netcharles.com/orwell/articles/col-1984quotes.htm :

Day by day and almost minute by minute the past was brought up to date. In this way every prediction made by the Party could be shown by documentary evidence to have been correct; ..."

but the *actual* prediction, which is that upon CO2 doubling, we will get between what is it, 1.5 and 6 degrees average global warming in about 100 years, has not been falsified yet, for the simple reason that we haven't been waiting yet for 100 years.

Do we need to? An actual last prediction is 0.2 degrees per decade. but how would that compare to the graph attached to that post? How about the start of the very first decade?

In complex modeling, it can happen that the finer details are wrong. This can indicate that the whole thing is misguided. It can also indicate that the general idea is right, but that the finer details are not understood.

Could it be that the general idea is wrong? Urging to look into the Miskolczi thread once more. The general idea about absorbtion of long wave Infra Red by greenhouse gasses heating the atmosphere is well known but until now real time data seem not to be supporting it, according to http://smsc.cnes.fr/documentation/IASI/Publications/LBL_EX.pdf.

But there is also Douglass et al 2007 and http://polarmet.mps.ohio-state.edu/PolarMet/PMGFulldocs/2007GL032630.pdf struggling with model ideas and refractory reality. So the question is, if the outcome of your calculations does not match the solutions in the back of your algebra book, are your assumptions and calculations correct?

 

[vanesch]

Could it be that the general idea is wrong? Urging to look into the Miskolczi thread once more.

In as much as I understand this (gave it only a diagonal look), the claim is that the radiation transport problem in 1 dimension is erroneously solved as of today ? I couldn't quickly figure out if this was some nitpicking about the best suited ideal boundary conditions of the radiation transport problem, or a fundamental mistake that people make today. I would think - but I know that this can be wrong - that such an elementary error would have been already spotted since quite some time, no ? After all, radiation transport in 1 dimension is not an insurmountably difficult problem !

 

[vanesch]

Do we need to? An actual last prediction is 0.2 degrees per decade. but how would that compare to the graph attached to that post? How about the start of the very first decade?

It is not impossible that a long-term trend is invisible for shorter time lapses simply because several oscillatory phenomena superpose upon it. I will be the first to agree with you that current modeling is far from perfect, and is way too much oversold. But in order to prove to me that no serious heating (or cooling for that matter) is happening when the CO2 contents doubles, you would JUST AS WELL need to provide me with detailed models that show me that the effect is NOT there. So as long as we don't have extremely reliable climate models, we cannot claim either way with certainty. I repeat, it was surely an error by the IPCC and the fearmongerers to say that there was any form of scientific certainty about AGW. But that fact by itself is in no way an argument that proves the "no" answer.

In other words, to the question: "a doubling of CO2, will it affect seriously the global climate ?", it would need a serious scientific effort and progress before an affirmative answer can be given with any form of certainty. But it would take just as much effort to give a negative answer to that question. It is not because a certain attempt at answering prematurely "yes" to the question failed, that this is a proof that it is "no".

What is falsified by current observations is only the *specific models* that the IPCC claimed were very sure and on which they based their "certainty" for the prediction of AGW. But it is not because this particular argumentation has been falsified that AGW by itself, independent of any modeling and claims, has been definitively shown absent either.

 

[Andre]

In as much as I understand this (gave it only a diagonal look), the claim is that the radiation transport problem in 1 dimension is erroneously solved as of today ? I couldn't quickly figure out if this was some nitpicking about the best suited ideal boundary conditions of the radiation transport problem, or a fundamental mistake that people make today. I would think - but I know that this can be wrong - that such an elementary error would have been already spotted since quite some time, no ? After all, radiation transport in 1 dimension is not an insurmountably difficult problem !

Well perhaps this thread and this thread are worth another look, especially the last post of Charles, which seems to make some sense.

 

[Andre]

...
In other words, to the question: "a doubling of CO2, will it affect seriously the global climate ?", it would need a serious scientific effort and progress before an affirmative answer can be given with any form of certainty. But it would take just as much effort to give a negative answer to that question. It is not because a certain attempt at answering prematurely "yes" to the question failed, that this is a proof that it is "no".
...

I don't know, are we moving the goal poles out of the realm of the scientific method? What is "affect seriously the global climate"? For instance, it may be recalled that the warmest period in the Holocene was termed "Holocene Thermal Optimum", and by no means "Holocene Thermal Disaster", when the trees grew on the Arctic coasts of Siberia (http://www.sscnet.ucla.edu/geog/downloads/634/269.pdf). Why would we think that a warmer climate would be disastrous in the first place? But anyway.

As far as I recall, the IPCC calls for a 1.5-6 degrees global temperature increase for doubling CO2, while the (MODTRAN HITRAN) models (see former post) get to about a dry one degree per doubling. The difference is explained by positive feedback. As stated previously Rizzi et al 2002, Douglass et al 2007 and Monaghan et al 2008 cannot produce results based on the models, but there is also a problem with that positive feedback (http://www.aai.ee/~olavi/2001JD002024u.pdf, http://www.aai.ee/~olavi/cejpokfin.pdf, http://www.aai.ee/~olavi/E-Ac-Sci-07.pdf and this thread).

Finally Miskolczi, using empirical evidence gets himself an idea that is close to zero degrees for doubling CO2, which would might make sense IMO if the emission of the absorbed IR is instantaneous without "exchanging heat" with other molecules, then a maximum of half of the IR emission would be reflected and half would escape to space, basically independent of the concentration of the greenhouse gas.

So what is it? And would any temperature change due to greenhouse effect be hazardous, indifferent or benificial to the climate?

Apparantly 20 years after the Hansen alert and umpty billion$ later, we are again at the basic questions.

 

[vanesch]

I d
As far as I recall, the IPCC calls for a 1.5-6 degrees global temperature increase for doubling CO2, while the (MODTRAN HITRAN) models (see former post) get to about a dry one degree per doubling. The difference is explained by positive feedback. As stated previously Rizzi et al 2002, Douglass et al 2007 and Monaghan et al 2008 cannot produce results based on the models, but there is also a problem with that positive feedback (http://www.aai.ee/~olavi/2001JD002024u.pdf, http://www.aai.ee/~olavi/cejpokfin.pdf, http://www.aai.ee/~olavi/E-Ac-Sci-07.pdf and this thread).

Again, that only means that we haven't yet a correct modeling (and maybe that our empirical observations are also not totally clean, I don't know). And if we don't have a correct modeling, we can't know what will happen, or even if something will happen. But that doesn't mean that we are now sure that nothing will happen. In order to be able to be sure about that, we would need to have a working model that shows us that nothing is going to happen, and we don't have that either.

So what is it? And would any temperature change due to greenhouse effect be hazardous, indifferent or benificial to the climate?

By definition, any human-induced change is hazardous, and any natural change is beneficial according to the currently political correct thinking.

Apparantly 20 years after the Hansen alert and umpty billion$ later, we are again at the basic questions.

Right. And it will probably still take several decades before we will find out a bit more, as we are talking about very slow processes. Now, if we could shake a bit the CO2 atmospheric content (making it rise, then making it fall etc...) we might probably find out better what is its exact function. But it is a world-wide experiment that will last for more than a century and will cost a lot of money.

 

[Andre]

Again, that only means that we haven't yet a correct modeling (and maybe that our empirical observations are also not totally clean, I don't know).

Well, isn't that called error margin? An wasn't there something about reproduceability? If several research teams, using several methods but getting consistent results, wouldn't that generate some confidence?

And if we don't have a correct modeling, we can't know what will happen, or even if something will happen. But that doesn't mean that we are now sure that nothing will happen. In order to be able to be sure about that, we would need to have a working model that shows us that nothing is going to happen, and we don't have that either.

Is this still about greenhouse effect? Will there be ever models that can predict what will happen? But I guess, you're thinking about http://www.aip.org/history/climate/cycles.htm having done quite spectacular things, which looked so easy to be solved with the greenhouse effect. Point here is that the reconstruction of that climate is a multitude of affirming-the-consequent fallacies, (not a reproach, there is simply no other way). But when things don't add up, some of those hypotheses are definitely wrong. The http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WPN-4S563X9-1&_user=10&_coverDate=05%2F31%2F2008&_alid=743566400&_rdoc=1&_fmt=high&_orig=search&_cdi=6995&_sort=d&_docanchor=&view=c&_ct=2&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=f01eff708f7c0b7ec2c7f31cb8e4e107 for instance is a major token of things not adding up. There is something very wrong out there. There is no way of modelling anything if you don't have the finger behind that.

By definition, any human-induced change is hazardous, and any natural change is beneficial according to the currently political correct thinking.

Nice challenge, is there anything benificial that only mankind could have done for nature? How about recovering all those fossil biomasses for burning, increasing the available carbon for the short carbon cycles and hence increasing the total biomass?

And it will probably still take several decades before we will find out a bit more, as we are talking about very slow processes. Now, if we could shake a bit the CO2 atmospheric content (making it rise, then making it fall etc...) we might probably find out better what is its exact function. But it is a world-wide experiment that will last for more than a century and will cost a lot of money.

Therefore perhaps it's better to sit back, make inventory and tick off the symptoms of scientific crisis as proposed by http://www.des.emory.edu/mfp/Kuhn.html. If it all matches, perhaps we should face reality and start from scratch, challenging all basic ideas.

 

[latecommer]

The solid evidence of temperature lag relative to CO2 at all time scales (as indicated by Gerlich/Tscheuschner, Jaworowski, Idso, Beck, and others). Indicates to me that even up and down movements of CO2 levels will be very difficult to analyse no matter how caused.
I would think that long term observations could best contribute to a solution of this question.

 

[vanesch]

Therefore perhaps it's better to sit back, make inventory and tick off the symptoms of scientific crisis as proposed by http://www.des.emory.edu/mfp/Kuhn.html. If it all matches, perhaps we should face reality and start from scratch, challenging all basic ideas.

Isn't it more a symptom of oversold science than of a scientific crisis ? If you make 20 guesses as hypotheses, put all that in some model, and turn the crank, should you really be surprised that some things don't fit ? But again, it is not because a model that makes two predictions and one of it is falsified, that this means that the other prediction is wrong too. What is correct, is that the *argument* for that other prediction now has a problem. But not necessarily the outcome.

Let's take a silly example: my theory is "if it is hot, it is bigger". I see that this works with an iron bar. I see that it works with water. So I make the prediction: summer days are hot, so they are longer than winter days. But then people show me wrong. They find hot stars that are smaller than cooler stars. They find hot girls that are smaller than cool girls... etc...

So my modeling that was based upon "if it is hot, it is bigger" has been falsified. A more careful analysis shows me that my theory only works for material objects, not for things such as days or girls. Also, I should compare identical material structures, and the only difference should be temperature. And even then it doesn't always work (some materials shrink upon heating). In other words, my theory that predicted "in summer, days are longer than in winter" is totally erroneous.

But that doesn't stop summer days to be *actually* longer than winter days. It is not because the theory that led to that prediction has been falsified that, as a fact, it became wrong too.

So it is not because some models of the IPCC are falsified in some of their predictions, and in some of their starting hypotheses, that the actual prediction of AGW itself is going to be false.

 

[Andre]

Or it was on purpose or you have no idea how dead on that example is. Bigger (as in heavier) is not necesarely hotter. Exactly! We're talking the bigger water isotopes now (dD and d18O). More later.

 

[Algr]

What is "affect seriously the global climate"? For instance, it may be recalled that the warmest period in the Holocene was termed "Holocene Thermal Optimum", and by no means "Holocene Thermal Disaster", when the trees grew on the Arctic coasts of Siberia (http://www.sscnet.ucla.edu/geog/downloads/634/269.pdf). Why would we think that a warmer climate would be disastrous in the first place? But anyway.

Get in your car, go to the expressway, and drive 60 mph. It's great to have transportation, isn't it? Now stand in front of a moving train, and have IT accelerate you to 60 mph instantly. Is that Optimum or Disaster?

Natural climate change happens over tens of thousands of years, giving biology time to adapt. CO2 in the atmosphere has shot up like a rocket this century - it's a rate of change unlike anything the Earth has ever experienced. How fast do you think those arctic trees can move?

And as for CO2's effects, why do you think that Venus is so much hotter then Mercury?

 

[TR345]

Someone told me, (not sure if I believe them, please correct if you can) that volcanos have had greater impacts on CO2 levels in the past than we can make. Is this true.

I am guessing that some of them may release more in a small chunk of time compared to fossil fuels, but that we continuously burn carbon while volcanos are periodical.

 

[Andre]

Isn't it more a symptom of oversold science than of a scientific crisis ? If you make 20 guesses as hypotheses, put all that in some model, and turn the crank, should you really be surprised that some things don't fit ? But again, it is not because a model that makes two predictions and one of it is falsified, that this means that the other prediction is wrong too. What is correct, is that the *argument* for that other prediction now has a problem. But not necessarily the outcome.

In a nutshell, remember that the theoretical increase in temp for doubling value for CO2 is around one degree celsius. No more, the reason that the IPCC expect ~2-4 is the perception of paleo temperatures during the Pleistocene having allegedly fluctuated 10 degrees sometimes as quickly as within a decade (Dansgaard Oeschger events). Why? Because of 'water' isotope ratios in the ice cores http://www.iceandclimate.nbi.ku.dk/about_centre/history/. So here is the vital affirming-the-consequent fallacy: if it's warm, the isotopes are heavy, the isotopes are heavy, hence it is warm. ( "if it is hot, it is bigger".) Again this is the main basis of the IPCC assumption as well as for the complete geology - paleo climatology. See Alley 2000

Now suppose that we were to discover that isotopes can be heavy without it being warm and that the well known isotope cycles in the ice core have a different cause. Also,
given the evidence for negative feedback from the Karner publications cited earlier, then there is no reason whatsoever to assume the enhanced sensitivity >1 C/2xCO2. Would that generate a Kuhn-type scientific crisis? It's not that fundamental physical laws have to be changed, it's just about erroneous interpretations.

And of course if Miskolczi is on the right track despite his error about the total energy of the atmosphere, and the real sensitivity is even a lot less, then some other theories are down the drain too.

 

[latecommer]

Vanesch

I can agree with the logic you follow when you say that proving a modal wrong does not prove the assumption wrong, But if you will, can you lay out the evidence that the assumption has merit?
As far as I am aware there has been very little if any confirmation of this basic assumption (human caused change to the atmosphere)

I believe it is accepted by nearly all that we have liberated a portion of the carbon cycle embedded in fossile fuels, and a measure of that has entered the atmoshpere.

Where the disagreement centers is... does this effect anything significantly?

So my concern is this: 1. What is the influence? 2. Is this influence, if any can be quantified, detrimental?
And why, if we can't difinitively answer these questions, are we embarking on global programs that have the potential of being a cure worse than the disease.

This is, IMO, the result of the overhyped "science" being sold to the public by and through their governments... an attempt to appear as if someone is doing something (so typical of our leaders)

 

[DrClapeyron]

Why melting ice caps are bad?

It would open up mineral exploration in the north pole, causing a new cold war era to usher in between russia and the usa. This will lead to a new space race but this time dominated by asthmatic nerdlings at NASA instead of the jarheadjocks of yor, the russians end up sending men to Mars before we can decide whether global warming is real or not.

 

[adb]

The only effect that increases in CO2 can have is to reduce the amount of radiation reaching the Earth's surface. However over the past 60 years there has been a steady decrease in humidity http://members.shaw.ca/sch25/FOS/GlobalRelativeHumidity300_700mb.jpg which would lead to increased radiation reaching the Earth and increasing temperatures. There has been some levelling off in the past decade or so at lower levels of the atmosphere.

Gerlich has clearly shown that there is no "atmospheric greenhouse effect".

 

[sylas]

The only effect that increases in CO2 can have is to reduce the amount of radiation reaching the Earth's surface.

Have a look at the absorption spectrum for CO2. It is transparent to light with wavelengths below 2microns, and this is over 90% of the solar spectrum. It has a weak absorption band around 2 microns, and narrow but stronger absorption bands around 2.6 and 4 microns. It also has a wider bad around 13 to 20 microns.

Together, these bands align with only a few percent of the solar spectrum. No matter how much you increase CO2, it cannot absorb more solar radiation than this. It's effectively transparent.

However, the 13 to 20 micron band takes up nearly 30% of the spectrum of infrared radiation from the surface, and the bands at 2.6 and 4 microns are also well into the main part of terrestrial infrared radiation.

It's very basic physics with more CO2 you will increase the absorption of light from the surface, but have little effect on the absorption of solar radiation.

Cheers -- Sylas

 

[adb]

It's very basic physics with more CO2 you will increase the absorption of light from the surface, but have little effect on the absorption of solar radiation.

Quite true. However there can be no nett heat transfer from the atmosphere to the Earth's surface as suggested by greenhouse.

 

[sylas]

Quite true. However there can be no nett heat transfer from the atmosphere to the Earth's surface as suggested by greenhouse.

Greenhouse suggests no such thing. In fact, greenhouse requires the nett heat transfer in the OTHER direction, from the surface to the atmosphere.

It is fundamental to the basic physics of a greenhouse effect that an atmosphere is colder than the surface, and that most of the radiation out into space comes from the atmosphere, not from the surface.

The atmosphere, therefore, must be radiating out into space close to what is being received from the Sun, less any small quantity of radiation that gets through direct from the surface. It is in the atmosphere, then, where you find the kinds of temperatures characteristic of what is needed to radiate that amount of energy.

Without an atmosphere, this temperature would be expressed right at the surface.

With an atmosphere, the surface must be warmer than the atmosphere, in accord with the second law, because the surface is warming the atmosphere.

The surface, therefore, must be radiating more energy than is received from the Sun... because it is at a higher temperature than would would be needed to radiate only the solar radiation alone.

By the first law, the surface must be receiving that same amount of energy from somewhere. In fact, it gets most of the solar radiation directly (because the atmosphere is mostly transparent to visible light) and on top of that it gets radiation coming back down from the atmosphere.

Now of course, the amount of energy from the atmosphere to the surface has to be less than that from the surface to the atmosphere, because the effect only works with a net transfer from the surface up into the atmosphere. That's fine; it follows direct from the laws of physics and thermodynamics. But there IS a flow in both directions. In practice, a small amount of the flow from surface to the atmosphere is by conduction and latent heat. But most of the flow is radiant energy.

This is a simple and inevitable thermodynamic consequence of any atmosphere which is mostly transparent to solar radiation, but which absorbs most of the infra red radiation coming up from the surface. We call this effect "atmospheric greenhouse". It's really really basic physics, and it is the primary reason why average temperatures on the Earth are so much higher than average temperatures on the Moon.

Cheers -- Sylas

PS. In a another thread, you yourself provided this diagram of the greenhouse effect. https://www.msu.edu/course/isb/202/ebertmay/drivers/ipcc_greenhouse.jpg

Have a closer look at the diagram. There's a very large flow up from the surface into the atmosphere, and back down to the surface again. It's on the right hand side. But bleeding off from this large arrow there are two smaller arrows, one of which empties into the atmosphere. That is the excess: it is there because the NET flow in a greenhouse effect is from the surface to the atmosphere. Furthermore, over on the left, there's another arrow from the surface emptying into the atmosphere. The diagram doesn't say, but this is actually for conduction and latent heat. This transfer is also part of the overall balance and must be considered for application of the thermodynamic laws. But even without this, the atmospheric greenhouse is still involving a net transfer from surface to atmosphere, just as I have said.

 

[adb]

Have a closer look at the diagram. There's a very large flow up from the surface into the atmosphere, and back down to the surface again.

Yes.

It doesn't exist.

Heat cannot flow in circles (or oscillate if you like) in this manner.

 

[sylas]

Yes.

It doesn't exist.

Heat cannot flow in circles (or oscillate if you like) in this manner.

Of course it can. This is really REALLY basic. Furthermore, those flows emphatically DO exist, and can be measured.

You are also misusing the term "oscillation". The real oscillations are changes in the energy flows, from effects like the change between night and day. The diagram is representing a mean value for the rate of energy flows; if we were able to show changes in the flows from night to day, you'd have effectively no input from the Sun at night, and a much larger input in the day. THAT is the oscillation.

What the diagram shows is the stable steady state mean condition of the equilibrium. It is absolutely stock standard basic thermodynamics to have items is a steady state condition with varying flows of energy between them. At equilibrium, the total energy flows into and out of any object are balanced, assuming no internal sources of energy. And that's what we have here. The only source of energy that really matters is the Sun.

But let's consider a simple example, which does not involve such oscillations, and involves a mutual exchange of energy between three objects.

Assume a planet, which is in tidal lock with the Sun, so that one side always faces the Sun and the other side is always in the night.

Assume a small black iron ball suspended just above the surface, in the middle of the side facing the Sun. The ball is a good conductor of heat; but because the planet is airless, it only exchanges heat by radiation. The ball is in the shade of a small mirror, which reflects away the sunlight.

Since there is no atmosphere, and no night or day, the planet reaches a steady temperature distribution. In the vicinity of the ball, this is just enough to balance the solar input at that point. The small ball receives infrared radiation from the planet on one side. The ball is small, and so it has a nearly uniform temperature distribution. By geometry, the ball's surface area is 4 times the cross section area intercepting energy from the planet's surface.

What temperature will the ball be, in relation to the planet?

Well, the planet has a temperature T. It radiates as a blackbody with σT⁴ W/m². The ball has surface area A. It receives 0.25*A*σT⁴ W from the planet. It radiates, however, due to its own temperature X, an amount A*σX⁴. It is in thermal equilibrium, so these two energy flows much be equal. Hence X is T/sqrt(2). The ball is about 0.707 the temperature of the planet. The ball radiates in turn. Half the energy goes out into space (the mirror is small and so the back of the mirror does not block this by much) and half the energy comes back to the planet.

The the final stable thermodynamic state, you have a flow of energy E from the planet to the ball, and 0.5E from the ball back to the planet.

Capiche? This is a stable state for the system. It's not oscillating, and you represent it with a steady continuous flow of energy from the planet to the ball, and another steady continuous flow in the reverse direction.

You can now add an oscillation if you really like, by rotating the planet. The ball spends about half its time in something like the state considered here, and about half its time in the cold of the night side, where all energy flows are very small. You can still represent the average of energy flows, which by the first law have to be in balance, and you still get an overall flow from the planet to the ball and a smaller flow back again. This is the stable equilibrium state of the system, which lasts for as long as the sun continues to shine.

To think this is a conflict with thermodynamics is just wrong.

I sympathize with the difficulties of anyone trying to learn thermodynamics. I've been there also and it is common as anyone is learning about physics and working through the concepts. What is really of more concern is the publication of a paper in IJMP(B), by Gerlich and Tscheuschner, which is full of really basic errors on thermodynamics; errors which any good first year undergraduate course on thermodynamics should be sufficient to fix. The journal really messed up in this case, and failed to apply the kinds of checking we should expect from them.

Granted, it is a small low impact journal. But it still reflects very poorly on the editorial board that this was not picked up before publication.

As a final exercise, try another simple idealized situation, where you should be able to apply the laws of thermodynamics and get an answer. A rapidly rotating planet is surrounded by a thin uniform shell, which transmits almost all sunlight, and absorbs almost all infrared radiation. What is the temperature of the planet, and of this shell?

The radiation from the Sun (S) falls through the planet. The planet radiates energy back up to the shell. The shell absorbs the radiation from the planet, and radiates in turn. The outward radiation from the shell must be S, to balance the inward solar energy. A thin uniform surface radiates back down by the same energy as goes out. Hence the shall radiates S back to the surface. The surface receives 2S, and radiates this same amount back.

Stable state condition. The shell receives 2S from the surface, and transmits S back down the surface again, and another S out into space. THAT is the "circle" you appear to think is impossible. But there is nothing whatever in thermodynamics to conflict with such a stable flow of energy. Everything balances, and since the shell will be cooler than the surface, the net flow from the surface to the shell is what we should expect.

Cheers -- Sylas

 

[sylas]

Excuse an addendum. I've found something that might help a bit; a description of some of the early measurements of backradiation from the atmosphere to the surface of the Earth.

The theory of the greenhouse effect was worked out from thermodynamics and radiative transfer long before global warming was any kind of an issue. This is not a question about global warming theory (which involves CHANGES to the greenhouse effect) but simply about the physics for why the Earth is so warm right now, by comparison with something like the Moon, just next door.

The major reason for the mild temperature we enjoy on Earth is the atmosphere, which works in some respects like a blanket. It absorbs energy from the Earth's surface, and (by thermodynamics) it re-emits that energy again. Some of the energy re-emitted in this way comes back down to the surface, and some of it goes back out into space, which is all precisely what we should expect from the laws of thermodynamics.

The radiation coming back down to the surface from the sky is easily distinguished from sunlight. Sunlight comes to us as high frequency visible light. Thermal emissions from the atmosphere will come to us as long wave radiation. The theoretical understanding of this was worked out long ago, and theoretical calculations of the expected back-radiation, based mainly on the absorption behaviors of CO2 and H2O, were derived by Walter Elsasser in the second world war, with the help of developments in quantum physics that are the basis for how light is absorbed and emitted by matter.

The term "back-radiation" has been around for this long as well.

One of the first attempts to measure this back-radiation directly, as a test of the theoretical predictions from thermodynamics and radiative transfer, was made in 1954. See: Stern, S.C., and F. Schwartzmann, 1954: An Infrared Detector For Measurement Of The Back Radiation From The Sky. J. Atmos. Sci., 11, 121–129. (online).

The paper, on page 126, makes two comments on the theoretical predictions of this backradiation. First, there is little variation between night and day. Second, the radiation is between 50% and 85% of the blackbody flux corresponding to air temperature near the ground.

Note, by the way, that the Earth has only small variations between night and day temperatures, by comparison with an airless planet. You may think it is much colder at night, but that's misleading. The difference is only around 25K or so, which is pretty small by comparison with the absolute temperature of 288K or so.

This was in 1954. It's not global warming theory; just thermodynamics of an atmosphere, predicted theoretically. The prediction is that there will be back radiation, and that it will be less than the upward radiation from the ground. The measurements recorded suggest the ratio has a mean of 0.76, and a standard deviation of 0.05.

I'm not well up on what developments have been made since then, but I hope this example may help readers understand that basic physics really does predict a substantial backradiation from the atmosphere, which will be less than the radiation proceeding up from the surface. If you think this is in any violation with thermodynamics, then you don't really understand thermodynamics yet. This is ok. It’s a hard subject. Just don't take one error-filled paper (Gerlich and Tscheuschner) in a small low impact journal as a basis for thinking that all the conventional textbooks on the subject must be wrong!

Cheers -- Sylas

 

[Algr]

Adb;

This might make more sense if you remember that Heat and Infrared are two very different things. Infrared is made out of photons. It is the same particle as light, so it behaves like light most of the time. It shoots from the Sun to the Earth at the speed of light, and passes through the clear atmosphere just like sunlight. It doesn't do much to the air.

But when infrared hits something opaque like the ground or the sea, it turns into Heat. Heat is NOT photons. It is the vibration of atoms and molecules. Heat does NOT travel at the speed of light - it moves by contact!

So the infrared photons from the sun hit the ground and warm it. Then the warm ground touches the cold air, and makes the air warm. BTW, that is why mountain tops are cold - they are surrounded by air that is usually far from the ground. That air doesn't get heated as much.

Heat can't travel from the air to space because there are no atoms there, so it gets stuck on Earth. That is the greenhouse effect. Over time, warm objects might emit infrared photons back into space. But the ability for that to happen depends on what kind of gasses are in the atmosphere. And because the Earth is so much cooler then the sun, the infrared FROM the Earth is at a much lower frequency then the infrared from the sun, and so behaves differently.

Have I got this right?

 

[sylas]

Heat can't travel from the air to space because there are no atoms there, so it gets stuck on Earth. That is the greenhouse effect. Over time, warm objects might emit infrared photons back into space. But the ability for that to happen depends on what kind of gasses are in the atmosphere. And because the Earth is so much cooler then the sun, the infrared FROM the Earth is at a much lower frequency then the infrared from the sun, and so behaves differently.

Have I got this right?

I do not believe so. It looks a bit misleading to me.

You say "heat cannot travel from the air to space". But that is equally true for a rocky airless surface like the Moon. Heat, in the sense you are using, cannot travel from an airless moon into space either. So you can't really say this is the "greenhouse effect".

But in fact, heat is more properly defined as the flow of internal energy between two objects by virtue of a difference in temperature. See, for example, the definition of heat supplied in our own physicsforum library resource. You'll get the same definition in nearly any modern thermodynamics textbook. Heat is specifically linked to the transfer of internal energy. We use the term internal energy, rather than "heat", to refer to the energy an object has by virtue of its temperature.

So actually, heat DOES flow from the top of the atmosphere out into the cold of space, by virtue of radiation. It also flows, in the same way, from the surface of an airless moon. So what is the difference?

The special feature of a greenhouse gas is that it absorbs infrared radiation, but transmits shortwave solar radiation. Even in a planet with a thick atmosphere, most of the heat leaving the surface does so by radiation, with a small additional fraction by conduction and also latent heat (a chemical process; but still heat, I believe). The thing about a greenhouse atmosphere is that the radiant energy from the surface cannot escape out into space, but flows into the atmosphere as well. The atmosphere, by virtue of its temperature, also emits radiation, but in all directions. Some comes back down to the surface, and some continues up through the atmosphere, with heat transferring by radiant heat flow (as well as by conduction and convention). Eventually, at a sufficient altitude, the photons have a chance to escape out into space without more interaction with molecules of the atmosphere.

Since we have most of the solar energy coming down to the surface, all of that energy has to get back out into space, by the first law. But in doing so, it flows up through the atmosphere, and by the second law there is therefore a gradient of falling temperatures in higher altitudes, up to the regions where the atmosphere has thinned out enough to let the photons escape. The second law, however, only constrains the NET flow of energy. But because molecules emit radiation in all directions, there are photons moving down as well as others moving up. At any level there is more radiation going up than down, because the lower levels are hotter and produce more radiant energy. Everything proceeds in strict accord with the requirements of thermodynamics.

So at the bottom of the atmospheric column there is a large flux of radiant heat energy in the atmosphere; and that becomes an additional flux of energy into the surface, along with the all the solar input. The surface then has to heat up enough to supply an equal flux of heat back out again, matching the sum of the solar input PLUS the additional backradiation coming from the atmosphere, all in strict accord with the first law. THAT'S the greenhouse effect.

Cheers -- Sylas

 

[Algr]

You say "heat cannot travel from the air to space". But that is equally true for a rocky airless surface like the Moon. Heat, in the sense you are using, cannot travel from an airless moon into space either. So you can't really say this is the "greenhouse effect".

Okay, that specific example may not be called "greenhouse effect" but it is something important that happens. I recall that during the moon walk, the ground was something like 200 degrees, but space suits could be cooled by venting water that would instantly freeze - i.e., the temperature 5 feet over the moon's surface was extremely cold. The rest sounds like what I said in different words. "internal energy" being what I called "heat".

 

[Skyhunter]

The special feature of a greenhouse gas is that it absorbs infrared radiation, but transmits shortwave solar radiation.

I think I know what you are driving at here but this statement is a little confusing. It does not transmit SW solar radiation, that would imply that it passes it on. Since it doesn't absorb it to begin with it cannot transmit it.

The special feature of a greenhouse gas is that it is predominately transparent to SW solar radiation while being opaque to LW Earth radiation.

 

[adb]

This paper shows that all that is needed to keep a planet warm is an atmosphere, without any "greenhouse".

http://www.geocities.com/atmosco2/atmos.htm?200820

 

[adb]

More from Heinz:

Greenhouse Gas Hypothesis Violates Fundamentals of Physics

By Dipl.-Ing. Heinz Thieme (Germany). Excerpt:

The relationship between so-called greenhouse gases and atmospheric temperature is not yet well understood. So far, climatologists have hardly participated in serious scientific discussion of the basic energetic mechanisms of the atmosphere. Some of them, however, appear to be starting to realize that their greenhouse paradigm is fundamentally flawed, and already preparing to withdraw their theories about the climatic effects of CO2 and other trace gases.

At present, the climatological profession is chiefly engaged in promoting the restriction of CO2 emissions as a means of limiting atmospheric warming. But at the same time, they admit that the greenhouse effect - i.e. the influence of so-called greenhouse gases on near-surface temperature - is not yet absolutely proven (Grassl et al., see here PDF ). In other words, there is as yet no incontrovertible proof either of the greenhouse effect, or its connection with alleged global warming.

This is no surprise, because in fact there is no such thing as the greenhouse effect: it is an impossibility. The statement that so-called greenhouse gases, especially CO2, contribute to near-surface atmospheric warming is in glaring contradiction to well-known physical laws relating to gas and vapour, as well as to general caloric theory.

The greenhouse theory proposed by the climatological fraternity runs as follows: Outgoing infrared radiation from the Earth's surface is somehow re-radiated by molecules of CO2 (mainly) and also O3, NO2, CH4 in the atmosphere. This backradiation produces warming of the lower atmosphere. To convince the public of the greenhouse effect, composites of temperature measurements since the 19th century are exhibited that show a certain warming. Measurements of the CO2 content of the air also show a rise in recent decades (Note CO2). Climatologists then claim that the CO2 rise has caused the temperature rise (see: here).

A second source of misconceptions about the relation between temperature and the CO2 content of air arises from an erroneous explanation of conditions on the planet Venus. The Venutian atmosphere is 95% CO2, and its near-surface temperature is approximately 460oC (see also here ). What climatologists overlook is that atmospheric pressure at the surface of Venus is 90 bar, and that it is this colossal pressure that determines the temperature.

Strict application of physical laws admits no possibility that tiny proportions of gases like CO2 in our atmosphere cause backradiation that could heat up the surface and the atmosphere near it:

1. The troposphere cools as altitude increases: in dry air, at a rate of around 1oC per 100m; under typical atmospheric humidity, by around 0.7oC per 100m. This cooling reflects the decrease of atmospheric pressure as altitude increases. Higher is cooler, both by day and by night.

2. Backradiation of the heat radiation outgoing from the Earth's surface would only be possible by reflection, similarly to the effect of aluminium foil under roof insulation. But the CO2 share in our atmosphere cannot cause reflection in any way. Within homogeneous gases and gas mixtures no reflections occur. As is well known in optics, reflection and even refraction occur only at the boundaries of materials of different optical density, or at phase boundaries of a material or a material mixture (solid-liquid, liquid-gaseous, solid-gaseous). Thus it occurs with suspended water drops or ice crystals, or at the boundary between surface water and air - but never within homogeneous materials, e.g. air, water, glass.

3. If outgoing thermal radiation from the Earth's surface is absorbed in the atmosphere, the absorbing air warms up, disturbing the existing vertical pattern of temperature, density and pressure, i.e. the initial state of the air layers. It is well known that warmed air expands and, because it is then lighter than the non-warmed air around it, rises. The absorbed warmth is taken away by air mass exchange. Just this occurs with near-surface air that is warmed by convection from Earth's surface, vegetation, buildings and so on. For the same reason the windows of heated rooms are kept closed in winter - otherwise the warm air would escape.

These facts are slowly but surely dawning on climatologists. Grassl and others state (see above) that radiation absorbed by CO2-molecules will warm the atmosphere if no other reactions occur in the physical (in particular dynamic) processes in the earth/atmosphere system. In these "idealised conditions", they say the greenhouse effect would be inevitable. Such "idealised conditions" must obviously include the proviso that air is stationary. It is really quite absurd that even now something so obvious as that hot air rises is not properly taken into account by the climatological profession. When air is heated up locally, it ascends and the warmth is removed. It also expands with decreasing atmospheric pressure at higher altitude, and cools so that no remaining warming can be observed. The warmth taken over by the absorbing air is transported toward the upper troposphere. The greenhouse effect does not occur.

The same process applies to individual CO2-molecules that absorb outgoing radiant heat from the Earth's surface or from lower layers of the troposphere. These individual molecules remain at the same temperature as their surroundings. Due to the high density of molecules in the troposphere, an immediate exchange of absorbed radiated energy takes place by convection with the surrounding molecules of air. The CO2-molecules in the air are not isolated and therefore cannot reach a higher temperature than their environment. If energy is absorbed, the molecules in the immediate vicinity will warm up.

4. A prerequisite for any type of heat transfer is that the emitter is warmer than the absorber. Heat transfer is determined by the ratio of the fourth powers of the temperatures of the emitting and the absorbing bodies. Because temperature is uniform within minute volumes of gas in the air, and temperature decreases with increasing altitude, back transfer to near-surface air of radiation from higher CO2-molecules is impossible. In fact, this is just as impossible as it is to use a to cooler heat radiator to heat up a warmer area.

5. The energy discharge from the troposphere takes place at its upper boundary layer, at the transition of the atmosphere from its gaseous state to a state approaching a vacuum. Only in this zone do gases start to emit even small quantities of energy by radiation. The other energy transfer mechanisms - thermal conduction and convection - which at denser pressure are far more efficient than radiation, no longer operate because of the low density of the atmosphere there. But from the surface where man lives and up to 10 to 17km altitude (depending on geographical latitude), gases transfer the small quantities of energy they might acquire from absorbed radiation by convection and conduction - not by radiation.

The climatologists derived the theoretical foundation of the greenhouse hypothesis from the concept of radiative equilibrium over the entire gas area of the atmosphere, right down to the Earth's surface. But the fundamental premise of radiative equilibrium - a balance of incoming and outgoing radiation - is correct only as long as it is limited to the vacuum-like zone of the upper atmosphere. In the lower regions of the atmosphere, the heat balance is essentially determined by thermal, i.e. thermodynamic equilibrium, which includes the thermodynamic characteristics of the components of the atmosphere as well as their changes in status.

6. From the upper atmosphere down to Earth's surface, air pressure rises continuously. The determinant of atmospheric pressure is the mass and the weight of that part of the atmosphere above the point in question. And as pressure increases, so does temperature. The rise in temperature is caused by the thermodynamic characteristics of the main components of the atmosphere, i.e. N2 and O2. Everyone knows that compression causes gases to warm: the effect is noticeable even when inflating bicycle tires. The atmosphere is no different...

Conclusion

Commonly held perceptions of the climatic relevance of CO2 and other so-called greenhouse gases rest on a staggering failure to grasp some of the fundamentals of physics. Correct interpretation of the Second Law of Thermodynamics and sound appreciation of the necessary physical conditions for emission of radiation by gases lead to the understanding that within the troposphere no backradiation can be caused by so-called greenhouse gases. Therefore it is not at all correct to speak of a thermal effect of these gases on the biosphere.

The thermal conditions in our and any atmosphere are determined by its pressure and the mass of its main components. Higher concentrations of CO2 in our atmosphere - at least until they reached 2% (a 60-fold increase) and thus became injurious to health - would endanger neither the climate nor mankind. To avoid further misunderstanding, the terms greenhouse effect and greenhouse gases should be avoided in describing the functioning of the atmosphere. A more correct term would be atmosphere effect. The operation of this effect is described in "The Thermodynamic Atmosphere Effect" here.)

It is completely incomprehensible and unjustified to imagine that mankind can or must protect the climate by attempting to control trace amounts of CO2 in the air.

 

[Skyhunter]

This paper shows that all that is needed to keep a planet warm is an atmosphere, without any "greenhouse".

http://www.geocities.com/atmosco2/atmos.htm?200820

That paper is not a peer reviewed publication.

The authors are claiming that gravity is the sole cause of the difference in temperature from a planet with an atmosphere and a planet without an atmosphere.

And that is nonsense.

 

[sylas]

I think I know what you are driving at here but this statement is a little confusing. It does not transmit SW solar radiation, that would imply that it passes it on. Since it doesn't absorb it to begin with it cannot transmit it.

Thanks. I'd like to be sure I'm using correct terminology.

My understanding is that it is perfectly correct to refer to the transmission of light through a transparent medium. The quantum theory for light in a transparent medium does involve absorption and reemission, with the same frequency and direction. The reemission is effectively immediate, because the vibration of the atom is not a natural vibration mode. This is distinguished from absorption at frequencies where the atoms or molecules are naturally able to hold that vibration, for long enough to collide with other molecules and pass on the energy as internal kinetic energy of the particles -- which is heating by absorption of light.

For example, we speak of the transmittance of the atmosphere, and of "atmospheric transmission windows" being the parts of the spectrum where the atmosphere is transparent. See, for example, Atmospheric effects at the Centre for Remote Imaging, Sensing and Processing (CRISP); or this this light tutorial at the physicsclassroom website.

The special feature of a greenhouse gas is that it is predominately transparent to SW solar radiation while being opaque to LW Earth radiation.

Quite so.

Cheers -- Sylas

 

[sylas]

More from Heinz:

[...]

2. Backradiation of the heat radiation outgoing from the Earth's surface would only be possible by reflection, [...]

This bland assertion is flatly false. Backradiation is ordinary thermal emission from the atmosphere; not reflection. It can be observed, and it is measured with a "pyrgeometer".

Heinz's paper is the same pseudoscience as appeared in Gerlich and Tscheuschner; but because his essay is shorter the errors leap out even more quickly.

Cheers -- Sylas

 

[adb]

I find it extraordinary that some people think that something has to be published to be worthwhile ... this in itself such a statement makes these peoples' comments worthless (because they aren't published).

Please try to give a more rational discussion of the above.

Heinz's point 3 above is particularly interesting on the departure from the idealized conditions assumed by greenhouse.

For those who want a published paper on the falsification of greenhouse, read Gerlich.

 

[sylas]

Heinz's point 3 above is particularly interesting on the departure from the idealized conditions assumed by greenhouse.

Point 3 is a very simple description of how convection works. There's nothing there at all about greenhouse, and most certainly nothing in the slightest departure from the conditions under which a greenhouse effect occurs.

Have you any comment on the direct measurements of atmospheric backradiation?

Cheers -- Sylas

 

[adb]

It's easy enough to measure radiation from anybody ... that's what pyrometers do in order to determine the temperature of bodies. Measuring radiation from a body does not mean that there is a nett flow of heat from a cold body to a warmer one.

The greenhouse effect ignores the movement of air via convection.

Water vapour is the major "greenhouse" gas. This graph shows humidity trends at various altitudes, over the past 60 years:
http://members.shaw.ca/sch25/FOS/GlobalRelativeHumidity300_700mb.jpg

With falling levels of the major "greenhouse gas", how is "greenhouse" supposed to be causing warming over this period ?

 

[Skyhunter]

Even Roy Spencer disagrees with Heinz Hug.

Hug only considers absorption and completely ignores emission in his "paper."

Thanks for clarifying your usage of the term transmission Sylas.

 

[Skyhunter]

It's easy enough to measure radiation from anybody ... that's what pyrometers do in order to determine the temperature of bodies. Measuring radiation from a body does not mean that there is a nett flow of heat from a cold body to a warmer one.

That would be contrary to the laws of entropy. The net flow would be from a warm body to a cold one.

The radiation you are measuring from a body is heat (energy) "flowing" from it.

The greenhouse effect ignores the movement of air via convection.

They are two separate phenomenon.

One is vertical heat transport and the other is radiative transfer.

Water vapour is the major "greenhouse" gas. This graph shows humidity trends at various altitudes, over the past 60 years:
http://members.shaw.ca/sch25/FOS/GlobalRelativeHumidity300_700mb.jpg

With falling levels of the major "greenhouse gas", how is "greenhouse" supposed to be causing warming over this period ?

That is nothing but a chart with no reference to source or data and against forum rules.

Regardless, relative humidity is not absolute humidity which is the proper measure of atmospheric water vapor content.

http://www.agu.org/pubs/crossref/2008/2008GL035333.shtml" is a link to the latest research on absolute humidity.

Between 2003 and 2008, the global-average surface temperature of the Earth varied by 0.6°C. We analyze here the response of tropospheric water vapor to these variations. Height-resolved measurements of specific humidity (q) and relative humidity (RH) are obtained from NASA's satellite-borne Atmospheric Infrared Sounder (AIRS). Over most of the troposphere, q increased with increasing global-average surface temperature, although some regions showed the opposite response. RH increased in some regions and decreased in others, with the global average remaining nearly constant at most altitudes. The water-vapor feedback implied by these observations is strongly positive, with an average magnitude of λ q = 2.04 W/m2/K, similar to that simulated by climate models. The magnitude is similar to that obtained if the atmosphere maintained constant RH everywhere.

 

[adb]

Even I disagree with the IPCC ... I can't see the relevance of Roy Spence's and my opinions, to my question:

1. Water vapour is the major "greenhouse" gas. This graph shows humidity trends at various altitudes, over the past 60 years:
http://members.shaw.ca/sch25/FOS/Glo...y300_700mb.jpg

With falling levels of the major "greenhouse gas", how is "greenhouse" supposed to be causing warming over this period ?

2. You might also please explain how greenhouse theory takes into account Heinz's comments.

3. Troposphere temperatures decrease almost linearly to 190 deg K at 100mbar. How do you suggest that greenhouse, together with convective circulation as described by Heinz, effect this profile ?

 

[Skyhunter]

Even I disagree with the IPCC ... I can't see the relevance of Roy Spence's and my opinions, to my question:

Well who are you to disagree with the IPCC?

I only pointed out that even the prominent skeptic Roy Spencer says that Hug's theory is based on false assumptions and a demonstrable lack of understanding of radiative physics.

1. Water vapour is the major "greenhouse" gas. This graph shows humidity trends at various altitudes, over the past 60 years:
http://members.shaw.ca/sch25/FOS/Glo...y300_700mb.jpg

With falling levels of the major "greenhouse gas", how is "greenhouse" supposed to be causing warming over this period ?

As I pointed out in my last post, that link is just a graph with no reference to source or data and is against forum rules.

And as I also pointed out in my last post, relative humidity is not absolute humidity and is therefore not a direct measurement of water vapor content in the atmosphere.

2. You might also please explain how greenhouse theory takes into account Heinz's comments.

I have no idea what comments you are talking about. I read the Hug paper a few years ago and have no interest in revisiting it. It has been thoroughly debunked and discredited and is not worth discussing.

3. Troposphere temperatures decrease almost linearly to 190 deg K at 100mbar. How do you suggest that greenhouse, together with convective circulation as described by Heinz, effect this profile ?

Like I said, I have no interest in revisiting the Heinz Hug debate. If you wish to then you can download the archived responses on John Daly's website. As for the linear decrease in temperature, well that is explained quite nicely by adiabatic lapse rate.

 

[sylas]

It's easy enough to measure radiation from anybody ... that's what pyrometers do in order to determine the temperature of bodies. Measuring radiation from a body does not mean that there is a nett flow of heat from a cold body to a warmer one.

Exactly! And therefore Heinz is wrong to say that the existence of backradiation violates any thermodynamics. There's backradiation, and there's a larger upward radiation.

The greenhouse effect requires a net flow of heat from the surface into the amosphere. All the diagrams that show how the greenhouse effect works show this. For example, look again at your own [post=2130172]msg #30[/post] of thread "Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics". You linked to http://www.climateprediction.net/images/sci_images/ipcc_fig1-2.gif .

The forward radiation (390 W/m²) is larger than the back radiation (324 W/m²). They both exist.

The greenhouse effect ignores the movement of air via convection.

Certainly not. All the diagrams also include the effects of convection... and also of latent heat, which are important for the the thermodynamics of planet. In the diagram you provided, they show up as 24 and 70 W/m² respectively.

Water vapour is the major "greenhouse" gas. This graph shows humidity trends at various altitudes, over the past 60 years:
http://members.shaw.ca/sch25/FOS/GlobalRelativeHumidity300_700mb.jpg

With falling levels of the major "greenhouse gas", how is "greenhouse" supposed to be causing warming over this period ?

Careful. You are mixing up two different things. What Heinz and G&T etc are claiming to refute is not the notion of global warming, but of any greenhouse effect at all. The greenhouse effect is keeping the planet some 33C warmer than would be the case were the atmosphere transparent to infrared. That is not about shifting temperatures; but the physics of temperatures experienced right now.

Whether or not there are physically credible concerns about how changing greenhouse gas compositions might affect the many interacting dynamic equilibria of climate, we'll make no progress unless we can get past the outright denial of fundamental thermodynamics as seen in Heinz' essays or in the G&T paper, which is what the thread has all been about so far.

However, I'll comment quickly on this more subtle point.

Yes, water vapour is the major greenhouse gas. The graphs you give are misleading. They are based on data from the NCEP Reanalysis Dataset. Caution: that data is mostly model based, rather than measurement, and there are all kinds of caveats on its reliability, particularly for earlier years. There's a FAQ on the page which details some of the issues. Also, we don't actually expect warming over that whole period. Also the graphs omit lower altitudes, where there is more water vapour. The graphs plot relative rather than specific humidity. They are thus pretty much hopeless as an indication of total H2O in the atmosphere. If you actually plot the total water content, using specific humidity and including lower layers where most humidity is found, you do actually get a slight increase. But it's really noisy all the same. There's more research available on humidity measurements, and so far indications are that there's an increase in the specific humidity, which is what you should really be looking at. (Addendum: Skyhunter backs this up very well, just above.)

This is getting into the genuinely interesting open research questions of climate science, and it is way more technical than the basic thermodynamics that's been used and abused so far in the thread.

Cheers -- Sylas

 

[adb]

There's another thread on this site on the same topic. I've just made a post about a sunbather receiving radiant heat of 324 from the atmosphere but just 168 from the sun.

Shade the sunbather from the 168 from the sun and she feels a chill. The add shade for the 324 radiating from the rest of the sky and she feels no change !

Thieme is suggesting that any temperature change due to absorption immediately results in convection, whereas the greenhouse model assumes a static atmosphere.

Yes, I'm aware that Gerlich and Thieme are suggesting there is no greenhouse effect at all. I'm also well aware of the volumes of evidence suggesting any such effect is negligible ... although falling humidity is interesting and I've seen no explanation. I also have no doubt that "average" global humidities are as questionable as "average" global temperatures ... but this is off topic.

3. Troposphere temperatures decrease almost linearly to 190 deg K at 100mbar. How do you suggest that greenhouse, together with convective circulation as described by Heinz, effect this profile ?

"... well that is explained quite nicely by adiabatic lapse rate. "

That is my understanding ... in other words are you suggesting that "greenhouse" plays no role in this temperature profile ?

 

[sylas]

There's another thread on this site on the same topic. I've just made a post about a sunbather receiving radiant heat of 324 from the atmosphere but just 168 from the sun.

Sufficient unto each thread are the bewilderments thereof. Let's leave her in that thread. There are many ways to describe the shaded sunbather, and (as is usual in physics) most of them are incorrect. The discussion can be perused at [post=2130326]#33[/post], [post=2130349]#34[/post], [post=2131659]#47[/post], [post=2131674]#48[/post], [post=2131684]#49[/post], [post=2131737]#51[/post] (so far) of the other thread.

Yes, I'm aware that Gerlich and Thieme are suggesting there is no greenhouse effect at all. I'm also well aware of the volumes of evidence suggesting any such effect is negligible ...

There is no evidence whatsoever for the greenhouse effect being negligible. It's measured, and works out to be the be equivalent of about 33C additional warmth averaged over the globe. The only rejection of greenhouse is crank pseudoscience in conflict with basic thermodynamics. It can be a useful exercise for interested students of physics to sort out those errors, but it is not an actual scientific debate.

I think some readers may have trouble distinguishing denial of greenhouse effects that occur right now in the current atmosphere, from debate over the magnitude of changes to the greenhouse that should be expected from changes in the atmosphere.

The latter is a more subtle problem, and there is real scientific debate on such changes. But even there, there's no good evidence for changes being "negligible". It's a question of how much climate change should be expected as atmospheric composition changes, and that's uncertain. The denial of the greenhouse itself is way way out in the far fringes of pseudoscience, on a par with thinking relativity is falsified by satellites, or that you can cure cancer with magnets, or that the Earth is young.

3. Troposphere temperatures decrease almost linearly to 190 deg K at 100mbar. How do you suggest that greenhouse, together with convective circulation as described by Heinz, effect this profile ?

That profile is called the lapse rate. The greenhouse effect has only a very small effect on that... but the lapse rate has a very large effect on the magnitude of the greenhouse effect! Basically, the greenhouse effect works because infrared radiation has a limited "optical depth" in the atmosphere. This means that radiation escapes to space from somewhere sufficiently high in the atmosphere that the radiation can get through. At this level, the temperature must be about -18C, because that gives the amount of radiation needed to balance the solar input.

The magnitude of the temperature impact at the surface from the greenhouse effect is therefore a product of this characteristic emission altitude with the temperature gradient given by the lapse rate. If there was no lapse rate, there would be no greenhouse effect, because the temperature at the surface would then be about the same as the point where radiation escapes to space. But the lapse rate itself is caused by the adiabatic movement of air, as Skyhunter has said.

Cheers -- Sylas

 

[jeffsubi]

There is so much emphasis on carbon dioxide as the anthropogenic agent of climate change that I thought it would be easy to find the empirical evidence. That is, the results of controlled experiments in which infrared rays at frequencies radiated by the Earth are beamed though columns of air containing 280 -380-ppm of carbon dioxide and the temperature difference measured. So far I have only been able to find the work of John Tyndall (1861). Given the equipment he had to work with it was understandably difficult for him to detect much of an effect of CO2, at atmospheric concentrations. Arrhenius admitted he didn't have the equipment, so he use indirect methods, including the moon as an infrared source.

If CO2 does not significantly increase temperature at atmospheric concentrations in controlled experiments, the whole edifice of managing GHG emissions in order to control climate collapses.

Have Tyndall's experiments been repeated with modern equipment?

If there are lots of publications, could someone post one or two key references please.

 

[adb]

There is so much emphasis on carbon dioxide as the anthropogenic agent of climate change that I thought it would be easy to find the empirical evidence.

If there was a shed of evidence that man's CO2 is causing warming, I'm sure the IPCC would also like to hear about it.

The rate of man's fossil fuel burning increased around 1200% after 1945 but the rate of warming from 1910 to 1940 is higher than any period after 1945.

While the Arctic is much discussed by alarmists, it was much warmer in the 1930's than currently.

 

[sylas]

There is so much emphasis on carbon dioxide as the anthropogenic agent of climate change that I thought it would be easy to find the empirical evidence. That is, the results of controlled experiments in which infrared rays at frequencies radiated by the Earth are beamed though columns of air containing 280 -380-ppm of carbon dioxide and the temperature difference measured. So far I have only been able to find the work of John Tyndall (1861). Given the equipment he had to work with it was understandably difficult for him to detect much of an effect of CO2, at atmospheric concentrations. Arrhenius admitted he didn't have the equipment, so he use indirect methods, including the moon as an infrared source.

If CO2 does not significantly increase temperature at atmospheric concentrations in controlled experiments, the whole edifice of managing GHG emissions in order to control climate collapses.

Have Tyndall's experiments been repeated with modern equipment?

If there are lots of publications, could someone post one or two key references please.

There are a range of simple experiments similar to what you describe intended for schools or home experiments. Beaming radiation through 400ppm CO2 is not really very sensible, however. The bottom part of the atmosphere (troposphere) is roughly 20 kilometers of air. To get temperature effects in a lab, you need to do what Tyndal did... use higher concentrations in a smaller lab setting.

There's a thread with some of the details you might like at [thread=312054]Need Help: Can You Model CO2 as a Greenhouse Gas (Or is This Just Wishful Thinking?)[/thread]. This seems to be what you are asking. It's home physics for experiments to show how thermal interaction with a gas can lead to heating.

The warming effect of gases that absorb infrared radiation is pretty fundamental physics.

Modern experiments go into much more fine detail than merely whether warming occurs; they are more concerned with nailing down the emission spectrum. An example of experiments intermediate between Tyndal and modern physics might be http://prola.aps.org/abstract/PR/v38/i11/p2000_1 (1931) by H.D. Smyth, in Phys. Rev., Vol 38, Iss 11, pp 2000-2015. This is looking at the details of what wavelengths are absorbed.

The spectrum now tends to be in part calculated from first principles, I think, using knowledge of how matter and light interacts, and I'm at a bit of a loss to give a simple experiment here; the range of experiments used to develop this level of understanding of the quantum physics is a bit daunting.

Cheers -- sylas

 

[sylas]

If there was a shed of evidence that man's CO2 is causing warming, I'm sure the IPCC would also like to hear about it.

The rate of man's fossil fuel burning increased around 1200% after 1945 but the rate of warming from 1910 to 1940 is higher than any period after 1945.

While the Arctic is much discussed by alarmists, it was much warmer in the 1930's than currently.

Let's stick with actually answering the question. If you want to discuss any of these claims you are making, I would suggest a new thread; and a credible reference to kick it off.

Cheers -- sylas

 

[jeffsubi]

Thank you sylas.

I went to the link you provided (Can you model CO2 as a greenhouse gas) and the person who tried the experiment says:

"The problem I'm having is that I haven't been able to obtain the anticipated results in any reliable way. In fact, I'm seeing no consistent variation in the temperatures of the two containers, and I'm starting to wonder if this experiment is based on wishful thinking rather than on hard science"

People who use wet methods to generate CO2 may indeed see an effect, but that could be due to the difference in water vapour and not the CO2. The same thing happens in the atmosphere, water vapour swamps CO2 as an absorber of infrared radiation.

Modern equipment is sensitive enough to do the experiment at 200 - 400ppm, in dry air with no water vapour. Some one must have done it. I would like to find the reference.

Thanks,
JEFF

There are a range of simple experiments similar to what you describe intended for schools or home experiments. Beaming radiation through 400ppm CO2 is not really very sensible, however. The bottom part of the atmosphere (troposphere) is roughly 20 kilometers of air. To get temperature effects in a lab, you need to do what Tyndal did... use higher concentrations in a smaller lab setting.

There's a thread with some of the details you might like at [thread=312054]Need Help: Can You Model CO2 as a Greenhouse Gas (Or is This Just Wishful Thinking?)[/thread]. This seems to be what you are asking. It's home physics for experiments to show how thermal interaction with a gas can lead to heating.

The warming effect of gases that absorb infrared radiation is pretty fundamental physics.

Modern experiments go into much more fine detail than merely whether warming occurs; they are more concerned with nailing down the emission spectrum. An example of experiments intermediate between Tyndal and modern physics might be http://prola.aps.org/abstract/PR/v38/i11/p2000_1 (1931) by H.D. Smyth, in Phys. Rev., Vol 38, Iss 11, pp 2000-2015. This is looking at the details of what wavelengths are absorbed.

The spectrum now tends to be in part calculated from first principles, I think, using knowledge of how matter and light interacts, and I'm at a bit of a loss to give a simple experiment here; the range of experiments used to develop this level of understanding of the quantum physics is a bit daunting.

Cheers -- sylas

 

[sylas]

Modern equipment is sensitive enough to do the experiment at 200 - 400ppm, in dry air with no water vapour. Some one must have done it. I would like to find the reference.

I honestly cannot imagine why anyone would bother. It would be a meaningless experiment, with no particular useful relation to the atmosphere or Earth system. Concentration is not all that important; the total amount is a more significant quantity. I don't think you'll find any such experiment with tiny quantities of a gas, giving temperature effects so small that you'd need pretty high quality experimental controls to even see them.

Cheers -- sylas

 

[jeffsubi]

OK, I'll settle for total amount. The change in CO2 concentration being talked about is from 280ppm to 380ppm, a difference of 100ppm.

If you take 1 square meter of Earth's surface and a column of air 1km high, a 100ppm of CO2 would be a 10cm slab at the bottom. Stick such an amount of CO2 in an appropriate container, beam through infrared at wavelengths radiated by the Earth and measure the temperature change.

I still maintain that modern instruments can measure EXTREMELY small temperature differences. Even with his rather basic apparatus Tyndall in 1861 was able to get measurable effects at concentrations of 'greenhouse gases' that occur in the atmosphere.

The protagonists for CO2 as the driver of global warming rest their claim on CO2 at concentrations found in air being able to absorb infrared, and warm the air (radiative forcing). That is the relevance of my experiment - can we demonstrate CO2 does this under experimentally controlled conditions, and to what extent?

Cheers,
Jeff

I honestly cannot imagine why anyone would bother. It would be a meaningless experiment, with no particular useful relation to the atmosphere or Earth system. Concentration is not all that important; the total amount is a more significant quantity. I don't think you'll find any such experiment with tiny quantities of a gas, giving temperature effects so small that you'd need pretty high quality experimental controls to even see them.

Cheers -- sylas

 

[sylas]

Jeff, here is a direct link taken from the other thread to a specific experiment that seems to be what you are looking for. http://www.espere.de/Unitedkingdom/water/uk_watexpgreenhouse.htm .

This experiment is aimed for schools, but it has been done quite carefully in the cited page.

There's not a great deal of value for professional scientists in doing this experiment to great precision, as described. It is certainly possible to measure temperature very accurately, but I honestly can't see much benefit in knowing the temperature change to great accuracy in this kind of set up. It won't tell you much about the atmosphere; it does not scale up trivially to let you draw useful conclusions.

To explain why, I'll give a brief discussion of how an atmospheric greenhouse effect works later in this post.

Nevertheless, there are more careful professional experiments with "gas cells" and the transmission of radiant energy. They are more concerned with measuring the properties of a gas than with trying to reproduce an atmosphere or prove a greenhouse effect in the atmosphere. You seem to be wanting some kind of experimental proof of the greenhouse effect. Tyndal's work gives you that, and though there may well be more or less equivalent experiments in more modern settings, I can't cite you one quickly that does precisely that; other than teaching experiments like the one cited above.

What I am wanting to say, without appearing snarky or discouraging, is that the atmospheric greenhouse is really basic physics. It's pretty much an immediate consequence of simple thermodynamics, given a gas with frequency dependent emissivity. There are all kinds of experiments confirming the details of thermodynamics and interaction of gases with radiation, and measurements of our own atmosphere that only make sense in the light of an atmospheric greenhouse effect.

What is more subtle is precisely how temperature profiles change with changes in concentrations of greenhouse gases, and for the atmosphere that depends on much much more than just the greenhouse gases themselves. That is, you need to distinguish between the matter of whether there is a greenhouse effect at all, with the question of how the effect changes as concentrations of gas change, in a complex climate system.

Gas cell experiments

One of the standard tools used for studying gases is a "gas cell"; a container of carefully measured gas within which transmission of radiation can be studied.

Just looking quickly, I can give you a reference to a paper showing a modern use of such a cell. See V.G. Arakcheev et al., (2008) Broadening of vibrational spectra of carbon dioxide upon absorption and condensation in nanopores, in Moscow University Physics Bulletin, Vol 63, No 6, Dec 2008. It's not what you want, but it does show the nature of the gas cells and the precisions of experiments. I picked that up with a quick google.

Another tool I've used a bit myself to play around is a simulator for gas cells. See Gas cell simulator at spectralcalc.com

(There's also a tool for calculating transmission in the atmosphere: http://geosci.uchicago.edu/~archer/cgimodels/radiation.html , at the University of Chicago.)

OK, I'll settle for total amount. The change in CO2 concentration being talked about is from 280ppm to 380ppm, a difference of 100ppm.

If you take 1 square meter of Earth's surface and a column of air 1km high, a 100ppm of CO2 would be a 10cm slab at the bottom. Stick such an amount of CO2 in an appropriate container, beam through infrared at wavelengths radiated by the Earth and measure the temperature change.

Sure, you could do that; but it wouldn't have a whole heck of a lot to do with the atmospheric greenhouse effect. Here's why:

Quick summary of atmospheric greenhouse

What actually happens in the atmosphere is that you get solar radiation coming in, and infrared being radiated up from the surface. When there's a gas in between which is opaque to certain infrared frequencies, it absorbs the radiation coming back from the surface, and heats up. Then, by virtue of having a temperature, the gas radiates in the same frequencies that it absorbs. This is radiated in all directions, back down as well back up out to space. And, of course, that radiation is absorbed again in turn. Each frequency of radiation has its own "optical depth"... the mean path length of a photon before it is absorbed.

We can measure directly the thermal "backradiation" that returns to the surface from the atmosphere; there are descriptions of this earlier in the thread. One way to think of the heating effect at the surface is to consider the additional radiation coming to the surface from the heated atmosphere, on top of the solar radiation.

But note... the backradiation depends on the temperature of the atmosphere as well as its emissivity, and so the net effect depends on other forms of energy transport, including latent heat and convection. Hence you can't represent an atmosphere either by having a small amount at the same concentration, or at the same total partial pressure.

Hence there's not really much point in an experiment just to measure a temperature change in a small amount of gas, apart from a teaching tool for practice in doing simple experiments and learning about radiative transfer in a gas.

I still maintain that modern instruments can measure EXTREMELY small temperature differences. Even with his rather basic apparatus Tyndall in 1861 was able to get measurable effects at concentrations of 'greenhouse gases' that occur in the atmosphere.

The protagonists for CO2 as the driver of global warming rest their claim on CO2 at concentrations found in air being able to absorb infrared, and warm the air (radiative forcing). That is the relevance of my experiment - can we demonstrate CO2 does this under experimentally controlled conditions, and to what extent?

Cheers,
Jeff

The experiments listed in the other thread do show that absorption of radiant energy by a gas can result in warmer temperatures than otherwise. As I've tried to show above, for studying climate we need a bit more than simply knowing a gas can heat up when it absorbs infrared radiation.

There is a paper mentioned in this thread which attempted to deny that there's a greenhouse effect at all. That's frankly outright pseudoscience; the climate equivalent of young Earth creationism. But sorting out how much temperatures on Earth change in response to changes in greenhouse gas concentrations is much more difficult. It can't be measured as a simple lab experiment, and constraints from actual empirical studies of the Earth itself only constrain the "sensitivity" of climate to comparatively crude precision.

I suspect this is not exactly what you were looking for, but I hope it might be some help.

Cheers -- sylas