Guest essay by Ed Hoskins
Using data published by the IPCC on the diminishing effect of increasing CO2 concentrations and the latest proportional information on global Man-made CO2 emissions, these notes examine the potential for further warming by CO2 emissions up to 1000ppmv and the probable consequences of decarbonisation policies being pursued by Western governments.
The temperature increasing capacity of atmospheric CO2 is real enough, but its influence is known and widely accepted to diminish as its concentration increases. It has a logarithmic in its relationship to concentration. Global Warming advocates and Climate Change sceptics both agree on this.
IPCC Published reports, (TAR3), acknowledge that the effective temperature increase caused by growing concentrations of CO2 in the atmosphere radically diminishes with increasing concentrations. This information has been presented in the IPCC reports. It is well disguised for any lay reader, (Chapter 6. Radiative Forcing of Climate Change: section 6.3.4 Total Well-Mixed Greenhouse Gas Forcing Estimate) [1]. It is a crucial fact, but not acknowledged in the IPCC summary for Policy Makers[2].
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The rapid logarithmic diminution effect is an inconvenient fact for Global Warming advocates and alarmists, nonetheless it is well understood within the climate science community. It is certainly not much discussed. This diminution effect is probably the reason there was no runaway greenhouse warming caused by CO2 in earlier eons when CO2 levels were known to be at levels of several thousands ppmv. The following simplifying diagram shows the logarithmic diminution effect using tranches of 100ppmv up to 1000ppmv and the significance of differing CO2 concentrations on the biosphere:
§ Up to ~200 ppmv, the equivalent to about ~77% of the temperature increasing effectiveness of CO2. This is essential to sustain photosynthesis in plants and thus the viability of all life on earth.
§ A further ~100 ppmv was the level prior to any industrialisation, this atmospheric CO2 made the survival of the biosphere possible, giving a further 5.9% of the CO2 Greenhouse effect.
§ Following that a further 100ppmv, (certainly man-made in part), adding ~4.1% of the CO2 effectiveness brings the current level ~400 ppmv.
§ CO2 at 400pmmv is already committed and immutable. So CO2 has already reached about ~87+% of its potential warming effect in the atmosphere.
Both sceptics and the IPCC publish alternate views of the reducing effect on temperature of the importance of CO2 concentration. These alternates are equivalent proportionally but vary in the degree of warming attributable to CO2.
The IPCC have published views of the total effect of CO2 as a greenhouse gas up to ~1200ppmv, they range in temperature from +6.3°C to +14.5°C, shown below:
There are other views presented both by sceptical scientists and CDIAC, the Carbon Dioxide Information and Analysis Centre. What these different analysis show the is the amount of future warming that might be attributed to additional atmospheric CO2 in excess of the current level of ~400ppmv. Looking to the future in excess of 400ppmv, wide variation exists between the different warming estimates up to 1000ppmv, see below.
A comparison between these estimates are set out below in the context of the ~33°C total Greenhouse Effect.
This graphic shows in orange the remaining temperature effect of CO2 up to 1000ppmv that could be affected by worldwide global decarbonisation policies according to each of these alternative analyses.
Some of the IPCC data sets shows very large proportions of the temperature effect attributable solely to extra CO2. The concomitant effect of those higher levels of warming from atmospheric CO2 is that the proportion of the total ~33°C then attributable the water vapour and clouds in the atmosphere is displaced so as to be unrealistically low at 72% or 54%.
It has to be questioned whether it is plausible that CO2, a minor trace gas in the atmosphere, currently at the level of ~400ppmv, 0.04% up to 0.10% achieves such radical control of Global temperature, when compared to the substantial and powerful Greenhouse Effect of water vapour and clouds in the atmosphere?
There are the clearly divergent views of the amount of warming that can result from additional CO2 in future, but even in a worst case scenario whatever change that may happen can only ever have a marginal future effect on global temperature.
Whatever political efforts are made to de-carbonize economies or to reduce man-made CO2 emissions, (and to be effective at temperature control those efforts would have to be universal and worldwide), those efforts can only now affect at most ~13% of the future warming potential of CO2 up to the currently unthinkably high level of 1000ppmv.
So increasing CO2 in the atmosphere can not now inevitably lead directly to much more warming and certainly not to a catastrophic and dangerous temperature increase.
Importantly as the future temperature effect of increasing CO2 emissions can only be so minor, there is no possibility of ever attaining the much vaunted political target of less than +2.0°C by the control of CO2 emissions[3].
Global Warming advocates always assert that all increases in the concentration of CO2 are solely man-made. This is not necessarily so, as the biosphere and slightly warming oceans will also outgas CO2. In any event at ~3% of the total[4] Man-made CO2 at its maximum is only a minor part of the CO2 transport within the atmosphere. The recent IPCC report now admits that currently increasing CO2 levels are probably only ~50% man-made.
On the other hand it is likely that any current global warming, if continuing and increased CO2 is:
§ largely a natural process
§ within normal limits
§ probably beneficial up to about a further 2.0°C+ [5].
It could be not be influenced by any remedial decarbonisation action, however drastic, taken by a minority of nations.
In a rational, non-political world, that prospect should be greeted with unmitigated joy.
If it is so:
· concern over CO2 as a man-made pollutant can be mostly discounted.
· it is not essential to disrupt the economy of the Western world to no purpose.
· the cost to the European economy alone is considered to be ~ £165 billion per annum till the end of the century, not including the diversion of employment and industries to elsewhere: this is deliberate economic self-harm that can be avoided: these vast resources could be spent for much more worthwhile endeavours.
· were warming happening, unless excessive, it provides a more benign climate for the biosphere and mankind.
· any extra CO2 has already increased the fertility of all plant life on the planet.
· if warming is occurring at all, a warmer climate within natural variation would provide a future of greater opportunity and prosperity for human development, especially so for the third world.
De-carbonisation outcomes
To quantify what might be achieved by any political action for de-carbonization by Western economies, the comparative table below shows the remaining effectiveness of each 100ppmv tranche up to 1000ppmv, with the total global warming in each of the five diminution assessments.
The table below shows the likely range of warming arising from these divergent (sceptical and IPCC) views, (without feedbacks, which are questionably either negative or positive: but probably not massively positive as assumed by CAGW alarmists), that would be averted with an increase of CO2 for the full increase from 400 ppmv to 1000 ppmv.
The results above for countries and country groups show a range for whichever scenario of only a matter of a few thousandths to a few hundredths of a degree Centigrade.
However it is extremely unlikely that the developing world is going to succumb to non-development of their economies on the grounds of reducing CO2 emissions. So it is very likely that the developing world’s CO2 emissions are going to escalate whatever is done by developed nations.
These figures show that whatever the developed world does in terms of decreasing CO2 emissions the outcome is likely to be either immaterial or more likely even beneficial. The table below assumes that the amount of CO2 released by each of the world’s nations or nation is reduced universally by some 20%: this is a radical reduction level but just about conceivable.
These extreme, economically destructive and immensely costly efforts by participating western nations to reduce temperature by de-carbonization should be seen in context:
§ the changing global temperature patterns, the current standstill and likely impending cooling.
§ the rapidly growing CO2 emissions from the bulk of the world’s most populous nations as they continue their development.
§ the diminishing impact of any extra CO2 emissions on any temperature increase.
§ normal daily temperature variations at any a single location range from 10°C to 20°C.
§ normal annual variations value can be as much as 40°C to 50°C.
§ that participating Europe as a whole only accounts for ~11% of world CO2 emissions.
§ that the UK itself is now only about ~1.5% of world CO2 emissions.
As the margin of error for temperature measurements is about 1.0°C, the miniscule temperature effects shown above arise from the extreme economic efforts of those participating nations attempting to control their CO2 emissions. Thus the outcomes in terms of controlling temperature can only ever be marginal, immeasurable and thus irrelevant.
The committed Nations by their actions alone, whatever the costs they incurred to themselves, might only ever effect virtually undetectable reductions of World temperature. So it is clear that all the minor but extremely expensive attempts by the few convinced Western nations at the limitation of their own CO2 emissions will be inconsequential and futile[6].
Professor Judith Curry’s Congressional testimony 14/1/2014[7]:
“Motivated by the precautionary principle to avoid dangerous anthropogenic climate change, attempts to modify the climate through reducing CO2 emissions may turn out to be futile. The stagnation in greenhouse warming observed over the past 15+ years demonstrates that CO2 is not a control knob on climate variability on decadal time scales.”
Professor Richard Lindzen UK parliament committee testimony 28/1/2014 on IPCC AR5[8]:
“Whatever the UK decides to do will have no impact on your climate, but will have a profound impact on your economy. (You are) Trying to solve a problem that may not be a problem by taking actions that you know will hurt your economy.”
and paraphrased “doing nothing for fifty years is a much better option than any active political measures to control climate.”
As global temperatures have already been showing stagnation or cooling[9] over the last seventeen years or more, the world should fear the real and detrimental effects of global cooling[10] rather than being hysterical about limited, beneficial or now non-existent warming[11].
References:
[1] http://www.grida.no/publications/other/ipcc%5Ftar/?src=/climate/ipcc_tar/wg1/222.htm
[2] http://www.powerlineblog.com/archives/2014/05/why-global-warming-alarmism-isnt-science-2.php
[3] http://www.copenhagenconsensus.com/sites/default/files/ccctolpaper.pdf
[4] http://www.geocraft.com/WVFossils/greenhouse_data.html
[5] http://www.spectator.co.uk/features/9057151/carry-on-warming/
[6] http://hockeyschtick.blogspot.fr/2013/11/lomborg-spain-wastes-hundreds-of.html
[7] http://www.epw.senate.gov/public/index.cfm?FuseAction=Files.View&FileStore_id=07472bb4-3eeb-42da-a49d-964165860275
[8] http://judithcurry.com/2014/01/28/uk-parliamentary-hearing-on-the-ipcc/
[9] http://www.spectator.co.uk/melaniephillips/3436241/the-inescapable-apocalypse-has-been-seriously-underestimated.thtml
[10] http://www.iceagenow.com/Triple_Crown_of_global_cooling.htm
[11] http://notrickszone.com/2010/12/28/global-cooling-consensus-is-heating-up-cooling-over-the-next-1-to-3-decades/
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@trick: the IR absorptivity of a polished brass tube is ~1.0.
Try again.
PS Thermalisation of absorbed EM energy can only occur at heterogeneous surface. it can never take place in a gas. The reason is that the IR density of states in a gas is determined solely by its temperature; the Law of Equipartition of Energy.
Kristian:
You have gone beyond ridiculous now. Let’s recap:
In your comment on August 13, 2014 at 1:05 am, you said:
“The mean upward transfer of energy by radiation from the global surface would be 63 W/m^2 in both cases [transparent and radiatively active atmospheres], Curt. And only that. As long as the average incoming from the Sun is still 161 W/m^2 and the mean conductive/evaporative energy loss rate is 97 (98) W/m^2, the surface can’t put out more energy than that by radiation.”
In my comment on August 13, 2014 at 11:24 pm, I cited the time and date of your comment and explicitly quoted you, adding the words in the square brackets you see above so that others could get the context.
I responded with the following comment:
“You are completely missing the very elementary fact that if the atmosphere cannot transfer any energy to space (which it could only do by radiation), it cannot on any ongoing basis get transferred to it energy from the earth’s surface. So to say that it would accept an average 97 W/m^2 on an ongoing basis from the surface when it radiates 0 W/m^2 to space is simply ridiculous.”
I even gave you the benefit of the doubt by analyzing two cases for an atmosphere transparent to LWIR, one where it is not completely transparent to solar radiation (reading you literally) and one where it is (what you may have really meant):
“If the atmosphere absorbed nothing in the visible spectrum as well as LWIR, the surface would absorb an average 240 W/m^2. Over the long term, the atmosphere would neither transfer energy to or from the earth’s surface, the only entity it could exchange energy with. The earth’s surface would need to be able to reject an average of 240 W/m^2, and the only avenue for it to do so is by radiating to space (which has an effective radiative temperature of ~0K, so it does not matter whether we look at it as uni-directional or bi-directional). So it would have to have a temperature of 255K (or less if varying) to do this.”
“If the atmosphere absorbed 79 W/m^2 of solar radiation (with 161 W/m^2 absorbed by the surface) but had no way of radiating LWIR to space, the earth’s surface would still need to radiate 240 W/m^2 to space, with the atmosphere transferring 79 W^2 to the surface (so there would be a temperature inversion in the atmosphere).”
Despite my very careful practice to quote you precisely, you accuse me of not doing so.
And now you have the unmitigated gall to accuse ME of making the mistake YOU made and I called you on. You said in your comment of August 14, 2014 at 8:21 am:
“If the atmosphere absorbs say 100 W/m^2 from conductive/convective heat transfer on a daily basis from the surface, but cannot radiate any of it away to space, how do you suggest the Earth system gets rid of it?”
Re-read the top quote of your comment in this post. YOU made the claim that a transparent atmosphere could absorb a steady flux of conductive/convective heat transfer from the surface even though it would have now way of rejecting that power anywhere, not ME. I pointed out how erroneous this analysis was, and now you accuse ME of the error!
Last year at Jeff Id’s blog, I made this comment about arguing with folks like you:
” You point out an inconsistency in their arguments, and they treat it as your inconsistency.”
You’ve just provided another example of this. You have brought this down to the level of the Monty Python “argument” sketch.
“You are completely missing the very elementary fact that if the atmosphere cannot transfer any energy to space (which it could only do by radiation), it cannot on any ongoing basis get transferred to it energy from the earth’s surface.”
Are you saying that the atmosphere can’t get heat from the surface by any means other than radiation? Because that is axiomatically false. The only reason the atmosphere can only lose energy to space in the form of radiation is because it is effectively a vacuum so no meaningful convection can occur… but I’d wager that some actually does occur (along with outgassing).
Alec M 1:57pm: No. The reflectivity of a polished brass tube is near unity – most of the incident photons live on, the rest of the photons are absorbed ceasing to exist, their energy living on, none are transmitted, none are “thermalised” in the lab.
rgb 3:31pm: “Um, you (Trick) do know about phase transitions, right?”
Yes.
“The melting ice is indeed being heated…”
Um, you do know heat doesn’t exist, right? Have you missed the events of the demise of the caloric theory? Heat is deceased, it has ceased to exist in modern natural science. Though like Monty Python’s dead parrot, some portray heat as being alive to make a sale. Energy & enthalpy live on.
“its temperature does not change because heat is not the same thing as internal energy!”
Um, you do realize per what you wrote 3:09pm this really is in modern science:
…temperature does not change because internal energy is not the same thing as internal energy!
You will want to re-think & restate that after thoroughly consulting with a thermo. prof.
“In particular, you are ignoring the change in entropy.”
True, as it is well known entropy increases as ice melts; I did not ignore the change in conserved enthalpy which is the explanation needed.
“Maybe you should take a thermo course at some point?”
Done. Passed. I recommend you catch up on your study by reading Bohren 1998 Atm. Thermo. text for thermodynamic internal energy and the 1st law with regard to demise of heat & follow-up on ice/water mixtures p. 22-28, p. 221-2 for ice-water equilibrium, then apply your learning to the freezing of lakes p. 355 for the thickness of ice with time. Very interesting and informative thermo.
looncranz: You ask: “Are you saying that the atmosphere can’t get heat from the surface by any means other than radiation?”
No! Please read what I said carefully. It was said in response to Kristian’s claim upthread that with a transparent atmosphere, the surface would still have a “mean conductive/evaporative energy loss rate of 97 (98) W/m^2” to the atmosphere.
I was pointing out that if the atmosphere had no way of rejecting an equivalent power flux, it could not continue to receive this from the surface. (If it started out colder than the surface, it could do so for a while, but eventually it would become as hot as the surface and these transfers would stop.)
In our atmosphere, the (poorly named) “greenhouse gases” have the ability to radiate power to space, so the atmosphere in general stays cooler than the surface and can absorb power from the earth’s surface conductively/convectively on an ongoing basis. But these same radiatively active gases keep the earth’s surface from radiating directly to space at many wavelengths.
Okay, so you are saying surface directly to space, the /other/ way of interpreting the quoted statement 😉
Very well, carry on good sir.
Curt says, August 14, 2014 at 7:43 pm:
“You have gone beyond ridiculous now.”
You always have to start out with an insult, don’t you, Curt? Just to try and establish some kind of superiority. Your game here is pretty transparent, you know that?
You have no case. You studiously avoid reading what I’m saying, the substance of my argument, rather picking small parts here and there that you feel you can argue against and stick to that, so as to divert from the main thrust of what I’m saying as much as possible.
You clearly know all the alarmist tricks.
Curt says, August 14, 2014 at 8:51 pm:
“In our atmosphere, the (poorly named) “greenhouse gases” have the ability to radiate power to space, so the atmosphere in general stays cooler than the surface and can absorb power from the earth’s surface conductively/convectively on an ongoing basis. But these same radiatively active gases keep the earth’s surface from radiating directly to space at many wavelengths.”
No, this is exactly what I’m pointing out to you that you seem completely blind to. It’s the very presence of the mass of the atmosphere that keeps the Earth’s surface from radiating its entire flux directly to space, Curt. Because it prevents the surface from ever reaching a purely radiative equilibrium with its heat source, the Sun. Because a large portion (the main portion, in fact) of the surface energy is transferred away through conduction/evaporation > convection. The surface energy is automatically brought up into the troposphere by convective processes. This is why Earth’s surface itself cannot radiate the final system flux to space.
The IR-active gases are just there, to do the job.
“It was said in response to Kristian’s claim upthread that with a transparent atmosphere, the surface would still have a “mean conductive/evaporative energy loss rate of 97 (98) W/m^2″ to the atmosphere.
I was pointing out that if the atmosphere had no way of rejecting an equivalent power flux, it could not continue to receive this from the surface. (If it started out colder than the surface, it could do so for a while, but eventually it would become as hot as the surface and these transfers would stop.)”
Yes, this is one of the great, poorly concocted fairy-tale stories of ‘Climate (Pseudo)ScienceTM’: If the atmosphere can’t cool by radiation to space, then this means in the end that the Earth system will become cold, not hot, because, because, at some point conductive>convective transfer from the surface will just stop – gone into thin air – and it will rather simply start radiating it all directly to space, cooling back to a steady-state temperature of 255K. Yippee!
This is what is beyond ridiculous, Curt! This story makes so many un-physical, unreal assumptions to get where it wants, that even a schoolchild should have no problems spotting them.
Addressing a few of these assumptions:
# How and why would the conductive/convective transfer of energy from surface to atmosphere just stop at some point? When is this point reached? And, more importantly, how do we stay there? You know that the atmopshere is free to expand, don’t you? That the air away from the solar-heated surface gets progressively thinner and therefore naturally colder the higher you go? You know also that the Sun never stops shining down on the surface? Why would the transfer stop before the surface had grown so hot and the atmosphere had grown so far as to start eroding into space?
# At the point where this peculiar non-conductive situation is seemingly reached, does the Earth system simply switch to full radiative loss from the surface? Does this situation all of a sudden turn into a pure radiative situation? Conductive/convective transfer to the fluid is forever eliminated as a mechanism for transfer of energy? How does this work? How is this maintained? The atmosphere is still there. The Sun is still shining. The surface still naturally ‘wants’ to shed energy to the atmosphere.
# So when the surface now all of a sudden is able to radiate the entire solar flux to space, does the enormous surplus of energy already in the atmosphere slowly convect/conduct back down, initially turned into a second heat source for the surface, by being warmer than the directly radiatively cooled surface, then finally reaching the same isothermal temperature of 255K? So at this point NO energy from the Sun passes from the surface at 255K to the atmosphere at 255K? As if the atmosphere weren’t there at all!
You can’t just block conductive/convective energy loss from a constantly heated surface surrounded by a fluid and expect to be rid of it, simply set it to zero and say “Now it’s gone, out of business.” and that now this situation is suddenly a purely radiative one, like a BB radiating directly into space, as if the massive atmosphere itself were gone all of a sudden, Curt.
You seriously don’t see the absurdity in this story? It’s just a story you throw out without even thinking it through. You’ve created a hyothetical bubble world, Curt, where even for the surface in the end nothing matters but radiation. Because the CO2 story NEEDS for this to be the case. It’s not. Reality doesn’t work like this. It’s all about convection. The mass of the atmosphere. You cannot ignore it. Come down from your pink little radiant cloud, down to Earth.
I explained to you how the world really works, Curt, here:
http://wattsupwiththat.com/2014/08/10/the-diminishing-influence-of-increasing-carbon-dioxide-on-temperature/#comment-1708851
I’d rather you address this. A much more interesting (and hopefully fruitful) discussion. Rather than your convenient dabbling in hypothetical scenarios that you clearly have no grasp of, but which can never be fully resolved because they can never be properly tested, so you can just go on and on with your nitpicking.
Listen. Energy is released from the solar-heated surface into the surface air layer through three different mechanisms: conduction, radiation and evaporation. But when the energy in this way is transferred to the air, convection takes over and transports it up through the tropospheric column towards the tropopause, from where it can be radiated to space. It’s as simple as that.
Curt, meet reality.
For a fluid in a gravity field and heated from below: Heating at the bottom (energy IN) > energy moving with the fluid up > cooling at the top (energy OUT).
Curt says, August 14, 2014 at 8:51 pm:
“In our atmosphere, the (poorly named) “greenhouse gases” have the ability to radiate power to space, so the atmosphere in general stays cooler than the surface and can absorb power from the earth’s surface conductively/convectively on an ongoing basis.”
You clearly don’t even understand the corollary of what you’re saying here.
Here’s the gist: Since convection is the ultimate cooling mechanism of a solar-heated surface beneath a massive atmosphere, somehow blocking for it will cause heating, not cooling. The IR active gases strengthens the convective cooling of the surface by radiating the surface energy at altitude to space. If you then take out these gases, efficient convective cooling of the (still) solar- heated surface would be impeded, and solar energy would thus automatically accumulate, making the surface warmer to reestablish (maintain) the temperature gradient. It wouldn’t respond by simply letting radiation take over. Even worse, by cooling below the original temperature (with convection working) as it did. No, the surface would naturally get hotter and hotter in order to strengthen convection to prevent the temp gradient from buckling, the atmosphere progressively expanding in the process. You see, the surface will automatically work this way, desperately trying to cool conductively/convectively to the atmosphere directly on top and will therefore accumulate the solar energy coming in until it can.
This ongoing nonsense about blocking for convection, the ultimate cooling mechanism of a heated surface surrounded by a fluid, and then get this surface to COOL (not heat) by just switching to radiation through the fluid instead, no more convection needed, is quite frankly sad to behold. It’s the perfect radiative delusion.
AlecM says:
August 13, 2014 at 10:29 am
“@Samuel C Cogar: there is an appalling lack of knowledge about radiative physics.”
—————-
I agree with your above, …… but I also think you really should have addressed the rest of your commentary to, … to wit:
matayaya says:
August 12, 2014 at 12:48 pm
Matthew R Marler says:
August 14, 2014 at 10:43 am
“That’s not so different from “trapping and releasing”. When I release animals back to the wild, I expect most of them get eaten by predators and few survive”
—————
Don’t be talking silly at me.
The Manager would throw that baseball player outta the game like “lickety split” iffen he held onto that baseball glove’s “absorbed” ball for more than a “New York instant”.
“HA”, and probably do the same iffen that baseball player emitted a “wild” throw or wildly threw it into the “wild”.
Kristian says, August 14, 2014 at 3:44 am:
“#8) The absorptivity of the air + the natural mechanism of buoyant/convective uplift upon warming (relative to surroundings) precludes ‘back radiation’ from ever having a noticeable influence back down towards the surface. The [radiative energy] is ‘forced’ to leak upward towards space, because that’s the way the convective conveyor belt moves. This is a fine-tuned machinery designed for the Earth to be able to rid itself of as much energy as it gets in.”
“#5) 4a+b automatically and naturally initiates convective uplift. In other words, the [energy originally transferred from the surface] is brought up and away from the surface air layer, into the atmosphere at large, by the process of convection – the bulk movement of air. This is, in simple terms, how energy is transported through a fluid: Heating (energy in) at the bottom > energy moving with the fluid from bottom to top > cooling (energy out) at the top.”
“[52.4 W/m^2 is] all the energy [radiative transfer from the solar-heated surface] has at its disposal. [None] of this energy returns to the surface. It is absorbed by the surface air, brought up by convection and emitted at altitude to space. Just like the conductive heat and the latent heat [from the surface]. That’s the way the energy from the Sun moves through the Earth system.”
Consider a pot full of water heated externally from the bottom and assume that the only way this body of water could ever rid itself of energy is through radiation.
How would this work?
The energy is coming IN from the external heat source at the bottom, absorbed by the lowermost layer of water in the pot, which would automatically warm, get slightly less dense and rise as a result. An upward convective current would thus naturally be established through the water column. The external energy originally brought into the volume of water from the heat source at the bottom would be – after initial absorption – transported up and away from the lowermost layer to spread through (mixed into) the volume at large, creating a temperature gradient in the process. In this way, the total volume of water would slowly be heated, not just the lowermost layer.
From wikipedia:
http://en.wikipedia.org/wiki/Natural_convection
“In natural convection, fluid surrounding a heat source receives heat, becomes less dense and rises. The surrounding, cooler fluid then moves [in] to replace it. This cooler fluid is then heated and the process continues, forming a convection current; this process transfers heat energy from the bottom of the convection cell to top. The driving force for natural convection is buoyancy, a result of differences in fluid density.”
But, you could say, there is also radiation going on all the time. All matter with a temperature radiates according to this temperature. And this radiation would be emitted in all directions – sideways, back, forth, up and down.
So the actual heated bottom of the pot would not just conduct energy as heat to the water. It would also radiate energy as heat.
Sure. The point is, the water would always absorb this radiation immediately. Liquid water is practically 100% opaque to IR (yes, it can move a bit further if the source is red hot, but certainly not much).
So what happens?
Yes, the water molecules always try to radiate (and they do it too), but as soon as the radiation is emitted, it’s reabsorbed and moved a bit higher through the parallel convective uplift going on. It can’t get anywhere by itself, either to the sides, down or up. Likewise the water molecules will try all the time to conduct energy away through collisions, to the sides, up and down. And they indeed do it. But it amounts to nothing. Conduction doesn’t manage by itself to actually move the energy anywhere, because as soon as it’s transferred from one molecule to the next, both molecules are moved higher no matter what happens, by the parallel convective uplift through the water column.
In other words, the actual movement of energy through the volume of water, away from the heating at the bottom, is done by bulk movement – convection. That’s a specialty of fluids. Microscopic radiative and conductive attempts at propagating some energy back down against this steady upward flow are futile. The natural and automatic process of convection simply sees to it that even these microscopic energy transports are always biased towards a relentless ‘leaking’ upwards, away from the source of the heating. Only the heating rate at the bottom and the cooling rate at the top ultimately matters to how fast the fluid/energy moves.
At the top of the water column, the convective current can’t move any further up. The radiation (and conduction) has simply been along for the ride up until this point. But here we’ve finally reached the ‘top of convection’. There is no more liquid water above to immediately absorb the radiation emitted by the water molecules. So the radiation being emitted UP from this level will be able to escape the volume altogether, out from the top surface. Into ‘space’.
As the water thus ‘dumps’ its energy at the top surface, it cools and sinks back down to the sides as a result, making way for new warm water coming up from below, becoming part of the already established convective cell.
This is in principle exactly how our atmosphere works also. Only the IR opacity is less complete (a fair share goes through the atmospheric window directly from the heated surface to space). AND, the atmosphere is 1) gravitationally getting less dense the higher up you go, and 2) capable of expanding upon heating, the body of water hardly at all.
I would once again encourage curious readers to peruse this article by the Chiefio – an excellent, empirically based exposition of how the atmosphere really operates, what matters and what doesn’t inside the troposphere:
http://chiefio.wordpress.com/2012/12/12/tropopause-rules/
I would also like to repeat what Sir George Simpson of the Royal Meteorological Society pointed out to Guy Callendar in 1938. It’s quite pertinent to what I’ve been saying here (and to Chiefio’s post above) about radiation vs. convection in the troposphere:
“…but he would like to mention a few points which Mr. Callendar might wish to reconsider. In the first place he thought it was not sufficiently realised by non-meteorologists who came for the first time to help the Society in its study, that it was impossible to solve the problem of the temperature distribution in the atmosphere by working out the radiation. The atmosphere was not in a state of radiative equilibrium, and it also received heat by transfer from one part to another. In the second place, one had to remember that the temperature distribution in the atmosphere was determined almost entirely by the movement of the air up and down. This forced the atmosphere into a temperature distribution which was quite out of balance with the radiation. One could not, therefore, calculate the effect of changing any one factor in the atmosphere …”
(Thanks, Konrad.)
Kristian says:
August 14, 2014 at 6:28 am
Kristian says, August 14, 2014 at 3:44 am:
“So you see, Curt, the 52-53 W/m^2 (or your 63) is the amount of energy that goes out from the surface by radiation to begin with. No more, no less. That’s radiation’s contribution to the surface energy balance between IN (from the Sun) and OUT (to the atmosphere/space). That’s all the energy it has at its disposal. Nothing of this energy returns to the surface. It is absorbed by the surface air, brought up by convection and emitted at altitude to space. Just like the conductive heat and the latent heat. That’s the way the energy from the Sun moves through the Earth system.”
The nonsense about the Earth’s surface having to radiate directly according to its temperature is based solely on a fundamentalist – and ultimately flawed – interpretation of the Stefan-Boltzmann equation: P/A = es*T^4. This equation specifically describes a situation where a black (gray) body is radiating into a perfect heat sink at 0 K. It is only applicable when the object radiating can be considered a ‘pure radiator’; either it faces no temperature at all or it is much, much hotter than its surroundings so that surrounding temperatures can be ignored (approximated as zero). In this case all we need to know is the temperature (and the emissivity) of the object radiating. Output (P/A) and temp is directly related.
Output and temp is NOT directly related when the object radiating is surrounded by temperatures fairly close to its own. Then the radiative heat transfer equation applies: P/A = es*(Th^4 – Tc^4). The energy (radiative heat) output from the radiating (hot) object in this case (like with Earth’s surface) is directly related rather to the temperature DIFFERENCE between it and its surroundings.
No the full equation is:
P/A = es*(Th^4 – To^4)+kconvection.s(Th-Tc)+kConduction.s(Th-Tc)
To and Tc aren’t the same, Tc would be the temperature in contact with the object, To could be at a distance. In the case of the Earth Th^4-To^4 is much larger than Th-Tc
A classic application of this is a thermocouple in a flame in a furnace, Tw=Th.
The thermocouple measures a lower temperature than the gases it is immersed in because of the losses, convection to the gases and conduction to the support wires both depend on the diameter of the wire and so the true temperature is approached as the wire diameter is decreased so one way to assess the error is to measure with different sized thermocouples in close proximity and extrapolating to zero diameter. That still leaves the radiative losses, these are dealt with by putting a radiation shield around the TC(a quartz tube for example), this reaches a much higher temperature than the distant wall and the error is much reduced.
In the case of the Earth there is only radiative loss so direct application is possible, the complication is that not all wavelengths are emitted from the same ‘surface’, that is the role of the GHG. The losses from the actual surface are more complicated.
“In short, they forgot to identify what actually happens before they made their ‘mental model’ and played with it.”
Curt. That’s you he’s talking about.
AlecM says:
August 14, 2014 at 1:57 pm
@trick: the IR absorptivity of a polished brass tube is ~1.0.
Try again.
PS Thermalisation of absorbed EM energy can only occur at heterogeneous surface. it can never take place in a gas. The reason is that the IR density of states in a gas is determined solely by its temperature; the Law of Equipartition of Energy.
No, for a gas molecule in equilibrium when it absorbs a photon it becomes out of equilibrium and then collisionally gives up energy to its neighbors thereby returning to equilibrium i.e. thermalizes
george e. smith says:
August 10, 2014 at 10:08 pm
If the CO2 effect (on surface / lower tropo temperature) is logarithmic, the going from 280 ppm to 560 ppm should give the same temperature rise, as going from 1 ppm CO2 to 2 ppm; or for that matter, from one molecule of CO2 per cubic meter, to 2 molecules of CO2 per cubic meter.
CO2 temperature response IS NOT logarithmic.
Maybe it id “non-linear” ; but it ain’t logarithmic.
The logarithm function is very specific.
As I’ve explained here several times before the CO2 effect is not logarithmic at all concentrations, at the range we see in the present atmosphere it is a good approximation. At low concentrations CO2 is a weak absorber an has a linear response, as the concentration increases it becomes a moderate absorber and the effect is approximately logarithmic, a further increase to a strong absorber and you have a square root effect (as in the case of methane now). That’s one reason why the graph in the original post is misleading because it shows an asymptote instead of the transition to square root (steeper) dependance.
“””””…..Phil. says:
August 15, 2014 at 11:18 am
george e. smith says:
August 10, 2014 at 10:08 pm…..”””””
I know you have explained it several (many) times Phil.
Al low ? concentrations, linear (roughly), at medium concentrations logarithmic (roughly), and at high concentrations, square root (also roughly).
So in the transition zones between low, medium, and high; just what mathematical functions does it follow (roughly) ??
And over the presumably reliable period of the Mauna Loa recorded data, the CO2 has gone up about 26-27% of one doubling, for which the logarithm function is not appreciably different from linear, and the recorded data is not capable of discerning which.
I’ll agree it is non-linear, and follows (accurately), no known elementary function.
What purpose is served by asserting ANY function, which is not followed by measured data ??
We don’t have any observed atmospheric “low” abundance data, nor do we have any observed atmospheric “high” abundance data. So what relevance are those non existent regimes ??
“””””…..August 14, 2014 at 7:55 pm
Alec M 1:57pm: No. The reflectivity of a polished brass tube is near unity – most of the incident photons live on, the rest of the photons are absorbed ceasing to exist, their energy living on, none are transmitted, none are “thermalised” in the lab……”””””
The reflectivity of a polished brass tube, is nowhere near unity. Freshly evaporated silver, with a quartz overcoat is about 98% reflectivity, for central visible wavelengths, and 2-10 micron IR.
Protected Gold is around 97% from 0.8 to 2.0 microns, and only 94% at 0.7-0.8 microns.
Protected Aluminum, is 85% for 0.4 to0.7 microns.
Copper is worse than Aluminum, and brass mimics copper (polished). Both tarnish rapidly in air.
george e. smith 12:47pm: “The reflectivity of a polished brass tube, is nowhere near unity.”
No. Various sources put emissivity of polished brass tested at 0.03. Since no photon is transmitted, the reflectivity is 0.97 which is near unity not “nowhere near unity” as you write. Reflectivity + absorptivity + transmitivity = 1.0. .97+.03+0.0=1.0
Kristian 9:04am: For some reason you leave out Callendar 1938 replying to Simpson in agreement with the top post:
“..in replying (Callendar) realized the extreme complexity of the temperature control at any particular region of the earth’s surface and also that radiative equilibrium was not actually established, but if any substance is added to the atmosphere which delays the transfer of low temperature radiation, without interfering with the arrival or distribution of the (energy) supply, some rise of temperature appears to be inevitable in those parts which are furthest from outer space.”
@george e. smith 8/15 12:26 pm
We don’t have any observed atmospheric “low” abundance data, nor do we have any observed atmospheric “high” abundance data. So what relevance are those non existent regimes ??
We have evidence of “high” abundance regimes in the geological history of the Earth. Depending on your definition of “low” we have evidence of low abundance regimes, too. Getting a handle on the uncertainties associated with different extrapolations of a variety of potential functions of CO2 absorption strength might benefit work in paleoclimate studies. It would at least be a reminder of how much we don’t know.
@ur momisugly Kristian’s quoted statement: August 15, 2014 at 9:04 am
“that it was impossible to solve the problem of the temperature distribution in the atmosphere by working out the radiation”
———–
Which is pretty much exactly what I have been saying for the past 10+- years, which is, to wit:
“I do not believe it is possible for anyone to measure the heating (warming) effect of the lesser quantity of gas (CO2) in a mixture of two different gases when the quantity of the greater volume of gas (H2O vapor [humidity]) is constantly changing from hour-to-hour, day-to-day and/or month-to-month.
Especially when said greater volume of gas (H2O vapor [humidity]) has a potentially 100+ times greater “warming” potential (40,000 vrs. 400) for said mixture than does the lesser volume of said gas (CO2) in said mixture”
——————-
@ur momisugly Kristian — I really don’t have a problem in reading and understanding your commentary and/or your verbiage use therein simply because I read it “in context” as to what I perceived your intent was when you penned it …… and not “in context” of what I think you should have written nor the exact verbiage that I think you should have used when writing it.
Everyone knows the meaning of the words “hot”, ”cold”, “warm” and ”heat” simply because they are four (4) of the first six (6) words that they were nurtured the meaning of before they quit wearing diapers. The other two (2) are “ma-ma” and ”da-da”. And all of those words and their meanings are still “written” in the DNA of their brain’s neurons and the person still uses them quite frequently “in context” depending on who they are conversing with.
Anyone who dislikes and/or objects to the use of the word “heat” ….. should also dislike and/or object to the use of the word “greenhouse” …… because they are “two peas in the same pod”.
To the majority of the populace the word “greenhouse” means the same thing as the word “heat”.
george e. smith says:
August 10, 2014 at 10:08 pm
If the CO2 effect (on surface / lower tropo temperature) is logarithmic, the going from 280 ppm to 560 ppm should give the same temperature rise, as going from 1 ppm CO2 to 2 ppm; or for that matter, from one molecule of CO2 per cubic meter, to 2 molecules of CO2 per cubic meter.
That is what I was pointing out to Nick Stokes way upstream in this thread.
CO2’s effect may be close to logarithmic from approx. 20 ppm to, perhaps, 2560 ppm and then begin to trail off.
This appears to be just one more item of “settled science” that is not settled.
Moreover, this CO2 effect is being described in a purely hypothetical, perfect laboratory environment. Can the effect ever be totally realized in the ever churning, swirling gaseous atmosphere while under varying levels of cloud cover and cloud reflectivity, solar fluctuations, orbital variances, cosmic radiation, etc.?
I’m not saying there isn’t some effect, but it simply will not stand still long enough for us to measure it.
@ur momisugly george e. smith says: August 15, 2014 at 12:26 pm
“Al low ? concentrations, linear (roughly), at medium concentrations logarithmic (roughly), and at high concentrations, square root (also roughly).
So in the transition zones between low, medium, and high; just what mathematical functions does it follow (roughly) ??”
—————
Keep asking those “good” questions, george e., ……… cause I enjoy watching them “wiggle n’ squirm” when attempting to think up an actual, factual and/or intelligently logical “answer” ….. to justify and/or explain the mimicry of their nurtured “religious” beliefs.
Saw this only now:
AlecM says, August 12, 2014 at 9:18 am:
“@davidmhoffer: to use your analogy with a resistor, ‘back radiation’ is a measure of potential, equivalent to the potential at one end of the resistor. It does not generate electric current. To do that you need a potential difference.
In the case of the Earth’s surface, the resistance is the process by which its heat is converted to electromagnetic energy. The rate of conversion of heat to EM energy is set by the difference of opposing radiative emittances (potential difference) at the surface plane.
Just remember this: ‘back radiation’ is like measuring a voltage. By itself it can do no thermodynamic work.”
Very well put.
And Hoffer’s response?
davidmhoffer says, August 12, 2014 at 11:04 am:
“It wasn’t an analogy. It was an example of something that Kristian claims doesn’t exist.”
Where do I claim that the POTENTIAL doesn’t exist, David? That’s exactly WHAT exists. The DWLWIR flow, the DWLWIR transfer of energy is what doesn’t exist as a real entity. Because, as Alec points out, you need a potential DIFFERENCE to generate flow. Just like an electric current. Or like wind. And the flow in the case of surface/atmosphere thermal exchange will then be the HEAT – the net of the opposing potentials. But you didn’t read this last part, did you David? Too much cognitive dissonance to handle for one day, I guess …