By Steve Goddard
The classic cure for hyperventilation is to put a paper bag over your head, which increases your CO2 levels and reduces the amount of Oxygen in your bloodstream. Global warmers have been hyperventilating over CO2 on Venus, ever since Carl Sagan made popular the idea of a runaway greenhouse effect. That was when he wasn’t warning about nuclear winter.
Sagan said that marijuana helped him write some of his books.
I bought off on the “runaway greenhouse” idea on Venus for several decades (without smoking pot) and only very recently have come to understand that the theory is beyond absurd. I explain below.
The first problem is that the surface of Venus receives no direct sunshine. The Venusian atmosphere is full of dense, high clouds “30–40 km thick with bases at 30–35 km altitude.” The way a greenhouse effect works is by shortwave radiation warming the ground, and greenhouse gases impeding the return of long wave radiation to space. Since there is very little sunshine reaching below 30km on Venus, it does not warm the surface much. This is further evidenced by the fact that there is almost no difference in temperature on Venus between day and night. It is just as hot during their very long (1400 hours) nights, so the 485C temperatures can not be due to solar heating and a resultant greenhouse effect. The days on Venus are dim and the nights are pitch black.
The next problem is that the albedo of Venus is very high, due to the 100% cloud cover. At least 65% of the sunshine received by Venus is immediately reflected back into space. Even the upper atmosphere doesn’t receive a lot of sunshine. The top of Venus’ atmosphere receives 1.9 times as much solar radiation as earth, but the albedo is more than double earth’s – so the net effect is that Venus’ upper atmosphere receives a lower TSI than earth.
The third problem is that Venus has almost no water vapor in the atmosphere. The concentration of water vapor is about one thousand times greater on earth.
Composition of Venus Atmosphere
0.965 CO2
0.035 N2
0.00015 SO2
0.00007 AR
0.00002 H2O
Water vapor is a much more important greenhouse gas than CO2, because it absorbs a wider spectrum of infrared light – as can be seen in the image below.
http://www.globalwarmingart.com/images/7/7c/Atmospheric_Transmission.png
The effects of increasing CO2 decay logarithmically. Each doubling of CO2 increases temperatures by 2-3C. So if earth went from .04% CO2 to 100% CO2, it would raise temperatures by less than 25-36C.
Even worse, if earth’s atmosphere had almost no water (like Venus) temperatures would be much colder – like the Arctic. The excess CO2 does not begin to compensate for the lack of H2O. Water vapour accounts for 70-95% of the greenhouse effect on earth. The whole basis of the CAGW argument is that H2O feedback will overwhelm the system, yet Venus has essentially no H2O to feed back. CAGW proponents are talking out of both sides of their mouth.
So why is Venus hot? Because it has an extremely high atmospheric pressure. The atmospheric pressure on Venus is 92X greater than earth. Temperatures in Earth’s atmosphere warm over 80C going from 20 kPa (altitude 15km) to 100 kPa (sea level.) That is why mountains are much colder than the deserts which lie at their base.
The atmospheric pressure on Venus is greater than 9,000 kPa. At those pressures, we would expect Venus to be very hot. Much, much hotter than Death Valley.
http://en.wikipedia.org/wiki/File:Emagram.GIF
Wikipedia typifies the illogical “runaway greenhouse” argument with this statement.
Without the greenhouse effect caused by the carbon dioxide in the atmosphere, the temperature at the surface of Venus would be quite similar to that on Earth.
No it wouldn’t. 9000 kPa atmospheric pressure would occur on earth at an altitude many miles below sea level. No such place exists, but if it did – it would be extremely hot, like Venus. A back of the envelope estimate – temperatures on earth increase by about 80C going from 20 to 100 kPa, so at 9,000 kPa we would expect temperatures to be in the ballpark of :
20C + ln(9000/(100-20)) *80C = 400C
This is very close to what we see on Venus. The high temperatures there can be almost completely explained by atmospheric pressure – not composition. If 90% of the CO2 in Venus atmosphere was replaced by Nitrogen, it would change temperatures there by only a few tens of degrees.
How did such bad science become “common knowledge?” The greenhouse effect can not be the cause of the high temperatures on Venus. “Group Think” at it’s worst, and I am embarrassed to admit that I blindly accepted it for decades.
Blame CO2 first – ask questions later.
=============================
UPDATE: Lubos Motl has written an essay and analysis that broadly agrees with this post. See it here
stevengoddard! I know! I know! It’s one gaztillion frillian! That’s true cuz I heard Vice President Gore say it.
Ric,
The diagram in the article shows various wet and dry lapse rates.
http://en.wikipedia.org/wiki/File:Emagram.GIF
Some people will argue, no matter how obviously correct a concept is. Temperatures increase at lower elevations, and decrease at higher elevations.
stevengoddard wrote:
“Merrick
Thanks for the explanation about spectral broadening. Much appreciated.”
Of course I mistyped – sent that in using my blackberry while getting ready this morning. The second width should have been 1000 kHz or 1 MHz. As type, 1000 MHz makes the statement incorrect. The upshot is: if the peak is broadened by a factor, x, then the average absorption is decreased by that same factor, x, such that the area under the absorption feature remains contant. The absorption strength is simply spread out over a larger portion of the spectrum. No more or no less photons get absorbed per molecule.
In situations where the absorption is very weak (very low concentrations) the broadening effect is exactly cancelled out by the lower absorption strength. In situations where the absorption is extremely saturated (extremely high concentrations) the impact is only at the edges of the large absorption feature. In intermediate cases (like on Earth) the impact is at is greatest. So relatively to Earth, this has a lesser impact on Venus.
Hey Anthony, ask Michael Hammer to post one or more articles here. He’s a spectrosopist who knows what he’s talking about. He posted several informative articles on Jennifer Marohasy’s blog.
One thing I don’t get with supposedly rational and objective people is the inherent jumping of the bridge mentality of jumping through a zillion hoops just to prove an obvious ridiculous claim.
Is it because it was writ in pedia and is supposedly verified by NASA? If that’s the case then it’s the most daft thing ever since NASA didn’t change their stuff until after the greenies went ape shit on pedia pages with their crap.
But of course something has to be true just because it has been assumed to be true, especially if it has been assumed to be true for so long.
This article is on par with what NASA should’ve kept, especially on their pages that are directed at kids, instead of boiling the venutians like lead with their pot-logic.
Dear Steve,
I apologize but your statement that only the pressure matters is silly, and you haven’t provided us with any evidence. You make “back of the envelope” estimates, and then you pretend the results to be accurate at “tenths of a degree”. Moreover, you neglect – and claim to be zero about – many physical effects, the greenhouse effect in particular, but you never give any evidence that it is legitimate to neglect them. Because it’s not.
I am going to write an article to debunk you.
Best wishes
Lubos
Luboš Motl
Huh? You might want to read the article a little more carefully before trying to “debunk” it. You must have missed the table in the article showing how temperature increases with each doubling of CO2.
Where do you see a claim of accuracy to tenths of a degree?
Oh, I see, the sentence says “few tens”, not “few tenths”. I take it back. I actually agree with this estimate.
@Stevengoddard: You said this “The high temperatures there can be almost completely explained by atmospheric pressure – not composition.”
In other words, you say that the gas pressure above Venus is what causes the higher temperature. What I am telling you is that you are 180 degrees facing the wrong direction. Gases only become gases because they have heat energy applied. Therefore the CO2 is only a gas because there is heat from the sun (or elsewhere if you prefer). Therefore the pressure is a function of the applied temperature not the other way around.
Philip Foster:
B. NASA released a report recently of the temperature fluctuations of the surface of the moon. Just like the earth it too shows a ‘greenhouse’ temperature elevation of 40K about the theoretical surface temperature. In other words neither the earth nor the moon (nor Venus) is kept warmer by any greenhouse effect
This is why there must be a change of paradigm: No one dares even to utter a single word against “consensus”: OK! then, the moon is made from cheese and comets are made of icecream.
Is that what you want?…but be careful, common people is now realizing that New Age Scientists did a lot of “mistakes”, and if, based on wrong bedwetters science, someone menaces to radically change their way of life, they will react by not believing in them anymore and politicians will adapt rapidly to this new environment (as they smartly and intelligently respond to “market”) and the outcome may be as tragic as leaving all bedwetter babies to starve (No more “milk” babies!) and that would be bad,bad news.
And…there is an additional justification: In harder economic times as these, Post Normal Science’ s precautionary principle will make them choose “to cut all unnecesary expenses”.
Ryan says:
May 7, 2010 at 8:20 am
So, are we to understand you mean to imply that a brown dwarf and a proto-planet have and maintain atmospheres in the absence of a parent star only by heating from radioactive decay and none from gravitational kinetic energy?
” I am embarrassed to admit that I blindly accepted it for decades.”
Man it’s nice to hear a smart scientifically literate person admit this, I don’t feel so bad. I too blindly accepted this. What I have also noticed is the phrase ‘runaway greenhouse’ implies that at one time, C02 levels were lower than today and that they somehow uncontrollably rose to comprise 95% of the atomosphere. And if we aren’t careful, we could cause the same thing to happen here. I have never seen evidence to suggest that venus ever had lower C02 levels than they are today. My understanding is that Venus has always had high CO2 in the atmosphere. Do we have evidence for low CO2 in the past and what was that CO2 concentration?
Eneagram
re NASA report. Not quite sure of what you are saying? The moon data shows the 40K elevation exactly like the earth does. What this means is that the theoretical baseline (calculated – clearly wrongly – from the Stefan-Boltzmann law of BBR) by ‘warmists’ is just wrong. Ie there is no greenhouse effect at all – either on the earth or on the moon or anywhere. CO2 has nothing whatever to do with warming the atmosphere. Which is what most of us knew anyway.
Luboš Motl
Got ya. I thought about changing the wording of that sentence to avoid confusion. Guess I should have done that.
******
PJP says:
May 6, 2010 at 1:17 pm
The references to Boyle’s and Charles’ law are not correct here.
In both cases they describe changes that take place when one of the parameters change.
In the case of Boye’s law it shows the relationship between volume and pressure WHEN TEMPERATURE IS HELD CONSTANT.
Avogardro’s law is more appropriate, which is basically:
(P1.V1)/(T1.n1) = (P2.V2)/(T2.n2)
P = pressure
T = temp (K)
V = volume
n = amount of substance
This shows that as you increase the pressure of a fixed quantity of gas its temperature increases and its volume decreases.
You know this from blowing up tires = as the air compresses, it gets warm.
Does the air in your tires STAY hot? (Answer – no).
But that doesn’t mean that it STAYS warm. Just because a gas is compressed doesn’t mean its hot forever. That would equivalent to perpetual motion.
This is the principle of a heat pump and air conditioner.
Something with a thick atmosphere is not forcibly hot at the surface just because of pressure.
******
PJP is correct. The act of increasing/decreasing pressure does produce heat/cold, but only from the amount of work input. Once compression or expansion stops, work stops, and the heat or cold will dissipate to ambient. A static atmosphere (like a planetary atmosphere) doesn’t produce any heat from compression, any more than a close-valved 2000 psi air-cylinder would. On Earth, localized compressional heating does indeed take place — Chinook winds or under strong high-pressure systems of descending air. But since the total mass of atmosphere doesn’t change, an equal amount of rising, expansion & cooling has to occur somewhere else to balance it. The net effect, temp wise, is zero. Yes, there is work going on in the atmosphere like blowing winds, air-compression, etc, and no work process is 100% efficient, so some waste heat is produced from this, but I’m certain this amount is insignificant.
But pressure does influence the GHG effect. An imaginary Venus with 100 earth atmospheres but only 390 ppm CO2 (like earth) would still produce considerably more GHG effect than on earth ’cause the CO2 partial-pressure would be 100x that of earth.
It’d be nice if we could measure the spectral properties of the Venusian atmosphere thru its entire depth. It seems to me that Venus has few ways to cool its surface — almost complete opacity above from the dense air and sulfurous clouds, and from what I’ve read, little air movement or convection at the surface. Any geologic heat from below would be “trapped” at the surface & lower air. Eventually over billions of yrs it would get mighty warm under there….
michael hammer,
So what you are saying is that the high temperatures on Venus are the result of high pressure. I could have sworn that was the point of this article.
The Venus so-called “greenhouse” effect started all this AGW bull.
Jim Hansen spread this erroneous idea.
Such is the limited amount of knowledge that this supposed Venus effect could ever be taken seriously.
Yet, it was taken seriously by many people.
This is a classic example where the scientists were wrong — and for many years maintained the fallacy — the thin “lab coat” line.
Indeed, some scientists still do maintain this idea — never admit you are wrong, just fade from the conference circuit and pass away from the picture.
Such is often the process of change in scientific circles.
Well, I tell you that kind of hide-bound process isn’t acceptable anymore.
Yes, I confirm the conclusions – that the greenhouse effect on Venus is just in dozens of degrees – independently, with many details about the lapse rates etc. clarified here:
http://motls.blogspot.com/2010/05/hyperventilating-on-venus.html
Thanks to Steve Goddard for pointing this interesting fact out, and sorry for my original criticism. I was selectively led to the independence of the composition statement, and both of us misread “tens” as “tenths” because we’re much more used to “tenths” than “tens” when degrees are discussed.
Cheers
LM
The 900 deg temps, the thick atmosphere, the dearth of craters, and its comet like tail (in dark mode) are all unique to Venus as a rocky body in our solar system. Perhaps it is not as old and does not have the same history as the other planets?
The runaway greenhouse effect and the periodic catastrophic resurfacing of the planet then would not be necessary theories in that case.
stevengoddard says:
May 7, 2010 at 9:06 am
michael hammer,
So what you are saying is that the high temperatures on Venus are the result of high pressure. I could have sworn that was the point of this article.
The high temperatures on Venus are the result of the high IR opacity of the atmosphere, due to CO2 and other gases such as SO2. The high opacity is the result of spectral broadening due to high pressure, high temperature and high concentration. Below is a figure showing a portion of the CO2 transmittance under the atmospheric conditions of Mars and Earth, the increased opacity on Earth is clearly seen, under the atmospheric conditions on Venus the transmittance is zero for that part of the spectrum indicating greatly increased opacity. The result of visible transparency and IR opacity gives rise to the ‘Greenhouse effect’.
http://i302.photobucket.com/albums/nn107/Sprintstar400/Mars-Earth.gif
There is one thing that hasn’t been mentioned here yet (afaik, I’ve read a lot but not all of the responses). Temperature is not a direct measurement of energy (heat) content, it is related to content through the specific heat (lambda) of the substance. This is why it takes less energy to bring ice to its melting point than it does to bring water to it’s boiling point. It’s because the greater degrees of freedom in liquid water vs ice means liquid h20 can store more kinetic energy before the temperature goes up. Perversely for water, when it becomes a gas it’s specific heat drops below it’s liquid phase. This means it takes less energy to make the same mass of water (as steam) go from 101C to 102C than it takes to go from 98 to 99C (as a liquid).
I couldn’t easily find any references/plots/data depicting what happens to the specific heat of gasses at Venus pressures, but I certainly do not believe it is static or within our human-weatherman-feeling of how our own atmosphere behaves. Does anyone have any information on this? I’d tend to believe specific heat would increase quite a bit, meaning the total ability of Venus’ lower atmosphere to store energy as heat would more resemble Earth’s oceans than it’s atmosphere.
Yes, it’s a lot more than pressure broadening. At one atmosphere the 4.3u symmetrical stretch of CO2 has an absorption length of 2 millimeters! The high pressure and temperature means that even transitions that are extremely weak will have absorption lengths that are tiny fractions of the atmospheric depths. It will radiate basically as a black body from the upper atmosphere, so there will be no pressure inversions, and consequently no convection cells.
Sorry, the greenhouse effect for Venus is real.
A thought experiment. Let’s create a fictional planet with no external source of energy. Drop in an atmosphere like that of Venus. Gravity would start bouncing all those little molecules around. Heat would be generated. However, eventually the heat would be dissipated to space by radiation. The molecules would slowly but surely fall to the surface where the gravitation energy would be transferred to the underlying surface. No more energy to heat the atmosphere. Eventually all the molecules would lie harmlessly on the surface.
Could someone explain what is wrong with this scenario.
If not, haven’t I just proven that the energy from the atmospheric pressure cannot, in and of itself, be the sole cause of the temperature of Venus?
Therefore, the energy comes from somewhere else. OK, we add the Sun and it gets the molecules moving again. However, the total heat energy should be exactly equal to what is provided by the Sun. If there is anything extra then it seems to me that must comes from something else, ie GHGs.
beng
What you are implying is that the temperature is the same in Death Valley and on Mt. Everest.
stevengoddard says:
May 7, 2010 at 9:06 am:
“So what you are saying is that the high temperatures on Venus are the result of high pressure. I could have sworn that was the point of this article.”
I don’t think the temperature is actually a RESULT of the high pressure; but the temperature is necessary to sustain the high pressure. Then the question goes back to “what sustains the temperature?” Is it a “greenhouse effect,” a “heat storage effect” or some combination. One cannot deny that the greenhouse gases absorb/emit IR. But since no empirical evidence seems to be available to demonstrate the greenhouse effect, one can only speculate about the impact of it. I happen to agree with those that accept the notion of greenhouse gas radiation, but think that convection overwhelms the effect. Otherwise, it should be a hell of a lot hotter in humid areas. In the end, perhaps the warmness of the Earth is due to storage of heat by water (mostly), and by the atmosphere.
Back to my Fiji question which nobody wants to touch: the water there is plenty warm to explain virtually all of the air temperature, without impacts from the copious amounts of greenhouse gases (water vapor) there. If you add the radiation from the water surface to any guestimate of “backradiation” from the air, it would have to be a hell of a lot hotter than the usual max. of about 33 C.