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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george e. smith says:
August 15, 2014 at 12:26 pm
“””””…..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) ??
Be my guest George:
http://www.physics.sfsu.edu/~lea/courses/grad/cog.PDF
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 ??
The log function is a result of the measurement for the concentration range present in the atmosphere.
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 ??
Our atmosphere includes the results of the linear phase as well as the log phase, graphs such as the one showed in the original post here get it wrong because they assume the logarithmic dependence for all concentrations of CO2 and are therefore wrong.
Phil. says:
August 16, 2014 at 7:06 am
george e. smith says:
August 15, 2014 at 12:26 pm
“””””…..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……”””””
Thanks for the math Phil; I have tucked it away for safe keeping.
One thing immediately stands out.
The entire outcome rests on the assumption of a unidirectional one dimensional path through a uniform slab of absorber, and presumes a Beer’s law Transmission.
Well, I think originally, Beer’s law was about absorption, and not transmission, so the transmission assumption, assumes that the photons, stay absorbed.
But they don’t, in the atmosphere. The absorbed photon is later re-emitted, perhaps frequency shifted, but in the same general neighborhood, and that re-emission is isotropic, not uni-dimensional, so the absorbed photons do not stay dead.
So it is the same case as a fluorescent absorbing medium. The incident spectral component, may be attenuated, but the net energy transmission is very much greater, because the photons are re-incarnated, and in the case of the CO2 and presumably other GHGs, the resurrection spectrum, is not greatly different from the incident one.
Which is why I say, the Beer-Lambert Law is invalid, for materials that re-radiate.
In the limit, where the absorbed energy is converted to heat (I don’t understand the QM of that ), some of the energy will propagate as thermal radiation due to the Temperature rise, and of course some of that heat would conduct or diffuse in all directions as well.
So the theory is pretty. It would be nice to know of any actual experimental observation, of a transmission conforming to that math, for ANY material example; even hydrogen. I can’t even imagine how one would experimentally verify such a transmission formula, in the lab.
But I do thank you for the paper. Sometimes I wonder what those line broadening expressions actually are.
For small values of (x), ln (1+x) = x , and also (1+x)^0.5 = 1+ x/2
So neither one is appreciably different from linear, for the range of x we have observed :
400/315 =1.27 ; ln (1.27) = 0.24 1.27^0.5 = 1.127
This is at least as close to linear as we can depend on data since IGY, 1957/58.
Kristian:
If you want to understand what effect something has, you need to understand what would happen without it. If you want to be able to start to analyze complex systems, you must be able to successfully analyze simple systems. This is why it is good to think about what would happen in a world with an atmosphere completely transparent to electromagnetic radiation.
You say:
“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).”
But for an atmosphere without radiatively active gases, there is no energy OUT. It has no way of transferring any energy out to space. This means, by absolutely trivial logic and calculation, this means that in the steady-state condition, there can be no energy IN.
You ask:
” How and why would the conductive/convective transfer of energy from surface to atmosphere just stop at some point? When is this point reached? ”
Do you really not know the answer to this? This point is reached when the temperature of the atmosphere, at the surface at least, reaches the temperature of the surface. When they are at the same temperature, heat transfer stops. If the atmosphere started out cooler than the surface, it would warm until it got to this temperature. If the atmosphere started out warmer than the surface, it would cool until it got to this temperature.
You then ask:
“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?”
Again, do you really not know the answer to this? It’s because the surface, unlike an atmosphere without radiatively active gases, has the ability to radiate power to space. Fundamentally, the surface under these conditions would rise to the temperature at which its output radiative power flux matches the solar input power flux.
Once again, you manage to get things completely backwards, believing that a radiatively inactive atmosphere has the ability to transfer power to space, but a radiatively active surface with close to blackbody emissivity does not!
Next you ask:
“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? ”
Have you never solved any coupled system of differential equations? Let’s review what goes on for this planet with a transparent atmosphere. The radiative power loss from the surface is (approximately) proportional to difference in the 4th powers of the surface temperature and the effective temperature of deep space. The conductive/convective power loss from the surface is (approximately) proportional to the difference in (the 1st powers of) the surface temperature and the atmospheric temperature at the surface.
A transparent atmosphere’s only power transfer mechanism is the conductive/convective one with the surface. If it is cooler than the surface, it will accept power from the surface, and its rate of change of temperature is this amount of power divided by its thermal capacitance. Because the power transfer is proportional to the difference in temperature, as the atmospheric temperature approaches the surface temperature, the rate of change of temperature decreases gradually, not “all of a sudden”. (As the solution to a first-order differential equation, it decreases on a negative exponential curve.) When atmospheric temperature reaches the temperature of the surface, there is no more power transfer and no more temperature change.
The surface has both the conductive/convective transfer with the atmosphere mentioned above (but any energy gain by the atmosphere is energy loss by the surface) and the radiative power transfer with space, so it is a little more complicated. But still, computing a steady-state temperature in response to a constant solar input is not difficult.
You continue:
“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.”
This state is maintained because the surface radiative losses to space match the incoming insolation and the atmospheric temperature matches the surface temperature. When this happens, the surface no longer “wants” to shed energy to the atmosphere.
Next you ask:
“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!”
The answer to your question is simply YES — no energy passes from the surface at 255K to the atmosphere at 255K. Why would it, when there is no temperature difference? You know the equations — USE THEM! This should be an absolutely trivial point, but you get it completely wrong. And yes, in the steady state it is “as if the atmosphere weren’t there at all!”
Then you assert:
“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.”
Now you’re just making s** up. The mass of the earth’s atmosphere keeps radiation from leaving like a black hole does???
You say:
“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.”
and go on to explain how convection cells form. And this would explain the behavior of an atmosphere that could NOT rid itself of energy just HOW????
I could go on and on and on, but there really is no point. Virtually every assertion of yours is based on a fundamentally flawed analysis. If you get the analysis of simple systems completely wrong, you cannot hope to start on the analysis of complex systems like the earth where many things are going on.
And yes, in the earth’s system, net convective/conductive power losses from the surface are highly significant. And analyzing how they might vary with changing radiative properties of the atmosphere is not at all easy or obvious, despite the claims of the alarmists.
But until you realize that these net transfers can only occur because of the radiative absorption of the atmosphere, and serve to lessen but not eliminate the temperature increase due to that radiative absorption, you cannot even get started on that analysis. And you allow the alarmists to say that skeptics don’t even understand basic physics. And that is what is so sad.
Curt says:
August 17, 2014 at 8:35 am
“If you want to understand what effect something has, you need to understand what would happen without it. ….. This is why it is good to think about what would happen in a world with an atmosphere completely transparent to electromagnetic radiation.
But for (a world with) an atmosphere without radiatively active gases, there is no energy OUT. It has no way of transferring any energy out to space. This means, by absolutely trivial logic and calculation, this means that in the steady-state condition, there can be no energy IN. ”
———————
Careful bout that now, ….. your above statement would only be true iffen the surface of said “world” was a perfect reflector of electromagnetic radiation.
But the earth’s surface is not a perfect reflector of electromagnetic radiation, but on the contrary, a pretty good absorber of said. Thus, there is energy IN and the surface temperature increases. And the surface is also a good emitter of IR, thus there is energy OUT.
Thus if the earth’s atmosphere was devoid of any radiatively active gases the aforesaid IR emissions would propagate directly into outer space. But the earth’s atmosphere will still “warm up” as a result of direct conduction of the thermal energy from the surface to the other gas molecules in the atmosphere (O2, N2). And those gas molecules in the atmosphere can “cool down” via conduction of their thermal energy back to the surface …… to be rid of via the aforesaid IR emissions. To wit:
———————-
“4. Conclusion
In summary, if there is no radiation source, CO2 approaches 0 K because of its emission;
absorption of the thermal radiation from the earth ground surface rises CO2 temperature from
-273.15°C to -78°C only. Carbon dioxide gains heat by molecular collision from nitrogen
and oxygen, and dissipate the gained heat by radiative emission. Considering gases are far
more effective than bulky objects in heat dissipation by emission, one would not surprise to
realise that it is non-radiative nitrogen and oxygen gases that award the Earth a warm liveable
near surface atmosphere”. http://www.tech-know-group.com/papers/JCao_N2O2GreenGases_Blog.pdf
Do we know why it is hot enough on the surface of Venus to melt lead?
Because of the planet’s extraordinary albedo, which makes it one of the brightest “stars” in the sky, less solar heat reaches the surface of that planet than reaches the surface of the Earth, per square foot.
The atmosphere of the planet, however, is over 90% carbon dioxide.
All this would seem to challenge that thesis that increasing concentrations of atmospheric CO2 have decreasing effects on global temperature.
“All this would seem to challenge that thesis that increasing concentrations of atmospheric CO2 have decreasing effects on global temperature.”
It would if Venus didn’t have such high atmospheric pressures. Model the earth’s atmosphere at 93 bar and see what happens 😉 oh, and add some nice 200MPH+ constant winds for some nice adiabatic forcing.
Warmists like to claim that Venus’s atmosphere was once like Earth’s but that a runaway greenhouse effect made the planet what it is today… but I know of not a single model that can account for that or that would say that Venus /should/ have had an earth-like atmosphere at any point. In science, after-all, the evidence is suppose to create the theories.
Samuel:
You misquote me by inserting the clause “a world with”, and then claim I am in error!
I said, “But for an atmosphere without radiatively active gases, there is no energy OUT.
The is no mechanism for energy OUT of the atmosphere to space. And that is correct.
Now that this thread has reached nearly 500 responses and has slowed down, I would like to ask my question again, as I’d really be interested in finding an answer.
Hoskins says this in his original essay:
“The recent IPCC report now admits that currently increasing CO2 levels are probably only ~50% man-made.”
Does anyone know where in AR5 (chapter, page) this 50/50 admission can be located?
@ur momisugly Curt:
I inserted that clause in parentheses therefore I was not misquoting you. My reason for doing so was to clarify your use of the word “atmosphere” for those spectators who might not be learned in/on the subject being discussed.
To wit:
at•mos•phere – noun: atmosphere; plural noun: atmospheres
1. the envelope of gases surrounding the earth (world) or another planet.
Jesse Fell says:
August 18, 2014 at 5:34 am
“Do we know why it is hot enough on the surface of Venus to melt lead?”
—————
“Yes”, we do know.
And one (1) of the primary factors responsible for the temperature of Venus’s atmosphere ….. to add to what ….. looncraz said: August 18, 2014 at 7:49 am
is the axial rotation of the planet Venus ….. Or the length of one (1) Venus day.
It takes 243 Earth days to rotate once on its axis ….. which means that +-50% of Venus’s atmosphere is being subjected to …. 121.5 earth days of continuous intense solar radiation.
Just imagine how “HOT” it would get in New York City or Miami iffen they were subjected to 121.5 continuous 24 hour days of intense bright Sunshine (solar radiation).
Samuel, I’m not sure I find that explanation convincing, for the following reasons:
1) While one side of Venus is continuously exposed to sunlight for 243 days, the other side is in darkness. If, owing to the length of Venusian days, one side of the planet is always smoking hot, wouldn’t the other be cold — and wouldn’t there be at least some exchange of temperatures between the day and the night of Venus? At any rate, the length of the Venusian day has no effect on the total amount of heat that it receives from the sun.
2) Owing to the density of Venus’ cloud cover, the amount of solar heat reaching the surface of the planet is a small fraction of the amount of heat that reaches the surface of the Earth — even though Venus is much closer to the sun. The albedo effect of Venus’ dense cloud cover — which makes it the brightest “star” in the sky — is extraordinary — like nothing on Earth.
3) Do you really think that the tremendous concentration of CO2 in the atmosphere of Venus (98%) can be dismissed as a factor in making Venus hot enough to make iron glow dull red?
At any rate, I kind of wish I didn’t know any of this stuff about Venus. “Perelandra” will never read the same again.
@ur momisugly Rick Cina
Sorry, but I can answer your question.
I have never read any of the IPCC reports …. and have no inclination of ever doing said.
@ur momisugly Jesse Fell:
“Climate and weather
Winds of about 224 mph (360 kph) keep the clouds of Venus in constant motion. Though the planet spins slowly, only once every 243 Earth days, the clouds zip around the top of the planet every four days. But wind speeds drop closer to the surface, where they only move a few miles per hour.
On Earth, seasons change based on the planet’s tilt; when a hemisphere is closer to the sun, it experiences warmer regions. But on Venus, most of the sun’s heat fails to make it through the thick atmosphere. As such, the planet not only doesn’t experience significant temperature changes over the course of the year, it also keeps things constant from night to day.”
http://www.space.com/18527-venus-atmosphere.html
Jesse, …… “most of the sun’s heat” …… doesn’t mean “all of the sun’s heat”, …. and “fails to make it through the thick atmosphere” means it doesn’t make it directly to the surface of the planet.
Samuel, That’s true. Midday on Venus looks like twilight here, so at least some light is getting through the atmosphere. But I’ve read that the amount of solar heat that reaches the surface of Venus per square unit of measure is a fraction of what reaches the surface of the Earth. If that is the case, how can it be hot enough to melt lead on the surface of Venus? The only explanation that I have read about — and it’s a very plausible one — is that atmosphere of Venus, being 98% CO2, creates a terrific greenhouse effect.
“The only explanation that I have read about — and it’s a very plausible one — is that atmosphere of Venus, being 98% CO2, creates a terrific greenhouse effect.”
The same reason only a portion of the sunlight reaches the surface is the same reason the surface is so hot. The surface can’t convect or radiate its heat away. This would be true of pretty much any 93 bar atmosphere, I’d think. Imagine our atmosphere at 1300 PSI (and also more mass). Sulfuric acid clouds are effectively opaque, so UV gets in, does its thing, downshifts in frequency, and can’t back get out.
I read a detailed examination once that normalized Venus to Earth pressures and couldn’t discern if CO2 was responsible for the heat (gases act differently as different pressures and concentrations). The lack of water vapor remaining prevents the positive feedback mechanisms claimed, and Earth’s wealth of water and magnetic field would prevent that from happening here, though many try to equate the two planets for their own agendas.
Curt says, August 17, 2014 at 8:35 am:
“But for an atmosphere without radiatively active gases, there is no energy OUT. It has no way of transferring any energy out to space. This means, by absolutely trivial logic and calculation, this means that in the steady-state condition, there can be no energy IN.”
Haha, I see Curt is still on with his magic pink dragons and unicorns climate physics.
How does he expect this particular (expandable) system to ever reach a steady state before it’s blown off into space, if it is not able to get rid of the energy constantly provided to it? Heat stops flowing (steady state) between two systems when there is only the two systems involved, Curt. When there ISN’T energy constantly being added from a third system, an external heat/power source, to the one system.
Curt is practicing the classical circular AGW way of doing ‘science’ by postulating his own premise as fact in order to show himself to be correct. Yup, there will be a steady state (because I say so), and FROM THAT you can see that I’m right. Priceless!
It’s not like the Sun stops shining, Curt. It’s not like the surface will all of a sudden find itself in a stable, purely radiative (BB) situation if you simply put a stop to conduction>convection. You can’t just set conductive/convective losses to zero and be rid of them. The real world doesn’t work like a mathematical equation; just strike out conduction/convection to get where we wanna be – radiation only. If you suppress natural conductive>convective transfer of energy from a constantly heated surface surrounded by a fluid, you will get warming, not cooling. Why? Because the energy from the heat source will accumulate at that surface until such transfer is restored. Naturally. Automatically. It’s what happens in the real world, Curt.
Energy from the surface could only completely bypass the atmosphere through radiation if it were much, much hotter than the atmosphere. It could hypothetically do this because conductive/convective loss grows linearly while radiative loss grows exponentially. But such a situation could never occur. The Earth couldn’t reach a state where its surface is at say 1000K and its atmosphere at a mere 300K. Because the two are directly convectively coupled. There would naturally be a gradual temperature gradient between them. Either there wouldn’t be an atmosphere in this case or the surface would have to be much, much cooler.
The surface energy, however, could not completely bypass the atmosphere through radiation if it were cooler, at the same temperature, or just a little bit warmer than the atmosphere above … In these cases the conductive/convective mechanism would be way too significant. The first two conditions would be highly unstable and could not be maintained, the latter one is similar to the one we have on our real planet, where our surface could at most let 52-53 W/m^2 bypass the atmosphere through radiative heat loss directly to space.
Kristian says, August 20, 2014 at 6:57 am:
“The Earth couldn’t reach a state where its surface is at say 1000K and its atmosphere at a mere 300K.”
Or 255K vs. 75K for that matter.
Hehe, sorry, forget about my two last posts (not the third last!). They refer to the situation where the temperature of an object’s surroundings can be ignored in a radiative exchange.
No, a heated surface surrounded by a fluid simply needs to be very hot, period, for radiative loss to dwarf conductive/convective loss to such an extent that it can be considered a pure radiator. Compare to a bonfire or a candle flame.
Jesse Fell says:
August 20, 2014 at 1:20 pm
The surface pressure of Venus’ atmosphere is about 93 times Earth’s. Mars’ atmosphere is also mainly CO2, but only with 0.06% Earth’s mean atmospheric pressure, so it’s a lot colder there, more than just lower insolation can account for.
At the point in Venus’ atmosphere where its pressure is one bar, its temperature is about the same as Earth’s average.
sturgishooper 1:33pm: “At the point in Venus’ atmosphere where its pressure is one bar, its temperature is about the same as Earth’s average.”
As the top post indicates, there is a diminishing influence of increasing ppm CO2.
And it is well known for long time, there is a big difference in general temperature between Earth & Venus at 1bar. Check out the 1 bar T difference shown in Fig. 1 here, T profile defined in papers cited in SI S.6 as early as 1997.
http://faculty.washington.edu/dcatling/Robinson2014_0.1bar_Tropopause.pdf
IGL P=density*R*T can be used further since the local density v. height was measured by Venus satellite radio occultation experiments. If input the measured density differences at 1bar, then find the same T since ideal gas law (IGL) works close approximation at both sites as should be expected, no big surprises.
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Jesse 1:20pm: “The only explanation that I have read about — and it’s a very plausible one — is that atmosphere of Venus, being 98% CO2, creates a terrific greenhouse effect.”
The above paper should add factors to your “only” explanation for Venus optical depth increased over that of Earth.
The paper explains that an atm. optical depth tau is increased by density, mass extinction coefficient, and mass mixing ratio of the atm. constituents, eqn. S14. Venus’ optical depth becomes so thick at surface due these factors, find Venus’ DWIR net of UWIR ~15,000 W/m^2 at surface pressure; generally Venus has no true atm. windows at IR wavelengths > 3 microns.
A greenhouse effect is taking place on Venus; the question is simply what causes it.
The article cited seems to imply that the composition of the atmosphere on Venus is relatively a matter of indifference; it is the density, mass extinction coefficient, etc. that render the atmosphere opaque to outgoing IR.
Granted, the extraordinary density and pressure of the atmosphere of Venus create a situation radically different from that on Earth. Still, can density, pressure, etc. be the only effective circumstances that bottle up the heat the reaches the surface of the planet?
In other words, other factors can be ruled in; but how is it that the properties of CO2 with respect to IR can be ruled out — especially given that the atmosphere is Venus is CO2 and very little else?
“In other words, other factors can be ruled in; but how is it that the properties of CO2 with respect to IR can be ruled out — especially given that the atmosphere is Venus is CO2 and very little else?”
They’re certainly not ruled out, but CO2 on Venus isn’t always even a gas, but a super-critical fluid exceptionally good at conducting heat with poor convective/radiative cooling from the atmosphere keeping that fluid nice and toasty no matter which side is facing the sun. Near-surface winds are very low as a result (effectively non-existent, since the surface is actually a super-critical fluid, no wind, more like a gentle current). This situation means there is very little convective cooling, and the sulfuric acid clouds mean there is very little radiative cooling.
Mars’ total warming as a result of having a nearly pure CO2 atmosphere: 5C. But that, of course, is without positive feedbacks.
@ur momisugly Jesse Fell says: August 20, 2014 at 1:20 pm
“If that is the case, how can it be hot enough to melt lead on the surface of Venus?”
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Jesse, the simple answer is, ….. the “mass density” of Venus’s atmosphere … and it actually has nothing to do with the type of gases in the atmosphere ….. as long as it isn’t H2O vapor.
Just kinda think of Earth’s atmosphere as being a cubic yard (meter) of fluffy feathers …. and Venus’s atmosphere of being a cubic yard (meter) of solid steel.
Or better yet, …. just read-up on ….. the effect of Urban Heat Islands, to wit:
http://www.epa.gov/heatisland/about/index.htm
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@ur momisugly Jesse Fell says: August 21, 2014 at 1:22 am
“but how is it that the properties of CO2 with respect to IR can be ruled out — especially given that the atmosphere is Venus is CO2 and very little else?”
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Now Jesse, me thinks you are assuming that all of the IR being emitted by the CO2 in Venus’s atmosphere is being DIRECTED toward outer space. Well now, … sorry bout that, …. said IR is being radiated in all directions …. plus the CO2 molecules are CONDUCTING thermal energy between each other, …. up n’ down n’ sideways throughout the entire atmosphere.
Thus, with a 98% CO2 concentration and a 93 bar atmospheric density ….. only the high altitude CO2 is radiating a portion of its absorbed IR into space.
And ps, Jesse, kinda ferget about that “greenhouse affect” because it doesn’t actually exist anywhere except within the confines of the enclosure of an actual greenhouse.
@looncraz 8/21 6:34 am
…. CO2 on Venus isn’t always even a gas, but a super-critical fluid exceptionally good at conducting heat with poor convective/radiative cooling
Thanks for that. I didn’t realize CO2 a Venus surface was in the super-critical phase.
An interesting phase diagram showing CO2 and H2O from 0K to 650 K, 1 mbar to 1 kbar
http://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Comparison_carbon_dioxide_water_phase_diagrams.svg/1280px-Comparison_carbon_dioxide_water_phase_diagrams.svg.png