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.
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UPDATE: Lubos Motl has written an essay and analysis that broadly agrees with this post. See it here
Venus is not volcanic like the Earth or Io is volcanic.
Something about this pressure = temp explanation does not fit correctly, with all due respect.
Clearly the energy reaching Venus is going into something, except for that which is reflected.
But the heat content of the atmosphere, at the massive levels on Venus, means it is much higher, no?
Consensus accepted post normal science can’t explain it. Holy Nasa neither. Only HE who explains how the interior of the earth reaches 2 million degrees can explain it.
Be highly praised our nefarious prophet!
ShrNfr
Good point about pressure broadening of spectral lines.
One more reason why pressure is the problem, not atmospheric composition – and why the Venus analogy doesn’t work on earth.
Peter Pan
The relationship between pressure and lapse temperature is exponential, not linear. Please look at the Y-axis on the left side.
http://upload.wikimedia.org/wikipedia/commons/1/12/795px-Emagram.gif
Wait! Has anybody seen if there on Venus cows live?….you know, all that cow farting can provoke such an elevated temperature. Gotto send some texan cowboys up there!
EPA should issue a ban on all venusian gases!. Big business ahead for Cap&Trade.
I did some back of the envelope figgerin’ about Venus here a year or two back. I don’t recall the numbers, but using the adiabatic lapse rate formula, I ran our N2,O2 atmosphere down to 90 atm, and got about a 100 degrees hotter than Venus. I ran Venus’ CO2 atmosphere up to 1 atm, and got around 20 or 30 degrees warmer than Earth, despite being so much closer to the sun.
NASA has a different adiabatic rate for Venus, however.
http://atmos.nmsu.edu/education_and_outreach/encyclopedia/adiabatic_lapse_rate.htm
which didn’t seem to fit from the lapse rate equation.
We don’t have a runaway greenhouse effect anywhere in the solar system, despite what dead tv personalities said.
I’m not buying it, did you read any scientific literature at all?
Bullock, Mark A.; Grinspoon, David H. (March 2001). “The Recent Evolution of Climate on Venus”. Icarus 150 (1): 19–37. doi:10.1006/icar.2000.6570.
Check for more:
http://plutoportal.net/~bullock/
http://plutoportal.net/~bullock/Homedocs/SciAm99.pdf
BTW The CO2 spectrum is completely saturated in the infrared at 90 atm.
http://members.casema.nl/errenwijlens/co2/lambertvenus.gif
Steve, my question is still whether when that russian spacecraft is at the bottom of an ocean or an atmosphere. Since the CO2 there is neither gas nor liquid but supercritical fluid, I’m not sure how you say. Remember that our space capsule, Liberty Bell Seven landed on the bottom of an ocean – like the Venera spacecraft. The difference was that Liberty Bell made a short bobble at a liquid gas phase boundary while Gus Grissom panicked and flooded the thing. Sure, light doesn’t penetrate but I am quite confident there was just rock where that space capsule landed at the bottom of the ocean. What do you suppose the density of CO2 is at the surface of Venus? I don’t know, but I suspect that it is much closer (on a percentage basis) to the density of liquid water than the density of air at sea level.
Even the greenhouse effect based on “common knowledge” for our earth is fundamentally misunderstood.
Imagine a atmosphere completely without any greenhouse gas and clouds.
That atmosphere would still be heated and cooled by our sun.
Heated by energy from the surface of the earth. Cooled by? Yes the same surface.
You can heat the entire atmosphere column from the bottom but not cool it from the bottom. It is a fluid where cooler air is denser. A cooling from the bottom is not efficient and THAT cause a greenhouse effect. The atmosphere will have a higher temperature than average surface temperature. Of course with consideration for the lapse rate in height.
If You then add greenhouse gases in this inert atmosphere is the cooling of the atmosphere enhanced…..
How did we get here?
With this kind of logic:
If a witch floats, she must be made of wood…
and what do you do with wood?
Burn it!
If Venus has 90% CO2 and is hot…
and Earth has .035% CO2?
It must mean APGW!
My apologies Carl Sagen, loved your show anyway.
@stevengoddard
Despite your explanations involving non-ideal gases, I still don’t find the pressure argument convincing. Apart from that the debunking of the runaway greenhouse effect is very good.
If I compress a set volume of air in a bicycle pump I can feel it get warmer. This is essentially the conversion of the molecular kinetic energy into sensible heat as a result of the decrease in entropy of the system. But as others have commented above, that heat dissipates out of the system quite rapidly. In order for this to be the mechanism of heating the Venusian atmosphere, there needs to be a constant cycling of (high level) low pressure gas down to the (lower level) high pressure atmosphere. The corollary to this thermal release in downward moving gas is that there needs to be upward moving gas to maintain the cycle.
This upward moving gas will expand as it rises, drawing the necessary energy from the surrounding gas and cooling it. I’m not sure that this has been demonstrated and, to be fair, you haven’t claimed any of this – it’s just implied by the physics I’ve assumed to be going on.
What you seem to be discussing in some your responses is the specific heat capacity of the gases which will increase with pressure. However, this relates to the themal capacity of the gas, not the thermogenic ability of the gas which is what is implied by your responses.
I like most of what you’re postulating, but maybe you can discuss the temperature question so more. I don’t think the analogy of a tall mountain stacks up. Pressure is a component in the thermal capacity of air at altitude but I’m struggling to see it as a thermogenic component.
“The effects of increasing CO2 decay logarithmically. Each doubling of CO2 increases temperatures by 2-3C. ”
Hang on here — so the climate sensitivity really *is* 2-3 degrees C? From everything I’ve seen at WUWT, I thought CO2 didn’t affect the climate. Or that increased CO2 followed increased temperature. Huh.
I have two questions. Not being a scientist, I am well aware that my two questions might be silly, but I’d really like to know the answers.
1. Why, if CO2 keeps certain wavelengths of radiative heat inside our atmosphere (creating a positive feedback) does it not also keep an equal amount from coming into the atmosphere in the first place (creating a negative feedback like clouds)?
2. It is my understanding that CO2 only traps radiation within a narrow spectrum of radiation. While measurements of the total heat coming into the atmosphere from the sun are measured in total watts per meter squared, does the composition of that radiation vary? If the amount of radiation that can be trapped by CO2 varies as much as the solar dynamics vary (active sun, passive sun, solar wind, cooling stars, etc.), do the models track for that in making their calculations for heat trapping by CO2 and the rest of the variations in global temperature?
Hans Erren
I made the point that it is the pressure, not the concentration of CO2 that is important. You seem to be agreeing with me, without realizing it.
In defense of HankHenry’s reference to an “ocean”, I believe he was talking about an ocean of CO2, not of water; and he made the interesting point that since the pressure and temperature at Venus’s surface exceed the critical pressure and temperature of CO2, it is just as valid to call it liquid as gas.
to stevengoddard
http://en.wikipedia.org/wiki/Supercritical_fluid
HankHenry,
The density of the atmosphere of Venus is 65. kg/m3 which is about one fifteenth that of water.
http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html
To stevengoddard
http://en.wikipedia.org/wiki/Supercritical_fluid
“Even worse, if earth’s atmosphere had almost no water (like Venus) temperatures would be much colder – like the Arctic. ”
And if earth’s atmosphere had no CO2, we would indeed be in that very state, since the earth would be a ball of ice.
In the case of Venus, if one presumes that Venus is a terrestrial planet and not a very small star, there is no other explanation for the surface temperature than the greenhouse effect, since greenhouse gases are the only gases capable of trapping heat. And naturally a very dense greenhouse atmosphere traps more heat than a very thin greenhouse atmosphere.
Johnny D
I have written a number of articles here discussing the greenhouse effect and the relationship of CO2 to temperature. Perhaps your preconceived notions about WUWT are not correct?
@Zeke
Mentioning Carl Sagans cannabis use is not a cheap shot or ad hom attack of any sort. It’s just simply stating facts according to Sagans biographer and others who knew him.
Biographer: Sagan Smoked Marijuana
Many people, like myself, treat a variety of medical conditions, like glaucoma, with cannabis. Check out a list of well known people that have/do use cannabis here at Very Important Potheads. Note that Al Gore is on the list. Actually the current and previous US presidents are on the list. Clinton should be listed but he’s in denial although Hillary makes the cut. The “founding fathers” of the USA were big time hemp farmers and pretty much stoners too.
R. Gates
Your ad hominem attack on Lord Monckton evidences the vacuity of your position. It appears you have neither scientific basis nor argument to address the substance of Monckton’s evidence and logic. For further evidence see:
Climate Change Reconsidered
By far the greatest immediate danger is the peaking of light oil and urgent need to provide alternative fuels to keep from a massive global deep depression. See:
World Liquid Fuels Supply, slide 8, in Meeting the World’s Demand for Liquid Fuels, G. Sweetnam, EIA, AEO2009.
World Oil Exports [00] Introduction Luis de Sousa
See discussion etc at The Oil Drum.
The most serious danger from “Climate Change” enthusiasts is that they divert the global community’s attention from the critical issue of the peaking of light oil and urgent need to develop alternatives on a war time footing.
The following values are from the NASA fact sheets as referenced from Steve Goddard’s link to “Composition of Venus Atmosphere”. This may help to explain the high pressure of Venus.
The comparison of the masses of the atmospheres:
Venus= ~4.8X10^20kg
Earth= 5.1X10^18kg
Mars= ~2.5X10^16kg
The comparison of the surface pressure of the atmoshperes:
Venus=92 bars
Earth=1.014 bars or 1014 mb
Mars=0.0087 to 0.0040 bars depending on season or 8.7 to 4.0 mb.
“”” Robert says:
May 6, 2010 at 12:04 pm
As far as i understood it would take two things to turn Earth into a seccond Venus, and that is enough time, and about twice the amount of energy from the Sun.
And this all to start building up the atmospheric pressure which needs a lot of time, more energy means more watervapour, more watervapour means higher pressure wich in result in an atmosphere wich is beter suited to hold an higher temperature. “””
Well where did you get the idea that water vapor increases the density of the atmosphere. H2O has a molecular weight of 18 versus 28 for Nitrogen or 32 for oxygen. So water vapor is way less dense than the rest of the atmosphere. CO2 on the other hand has a molecular weight of 44 which is more than double what H2O is.
Seems to me that on earth approaching storms are signalled by a pressure drop; not a pressure increase; not that I am suggesting that is simply due to the amount of moisture in storms.
does it not occur to anybody that Water alone, in the earth atmosphere forms clouds in its liquid and solid phases; and clouds always cool the surface in the shadow zone; by reflecting sunlight back into space (albedo) and blocking further sunlight from the ground due to the optical density of the cloud.
It was reported, that Professor Stephen Schneider of Stanford; the apparent inventor of Climate sensitivity, and the myth of a lgarithmic surface temperature connection to CO2 abundance; in his criticism of the recent “Climategate” book by Meteorologist Brian Sussman; in which Schneider is reported to have dismissed Sussman as “misfiring on all cylinders” and pooh poohed Sussman’s statement that H2O was the principal cause of greenhouse warming on earth; not CO2.
Scneider is reported to have said that H2O is a very weak GHG whereas CO2 is a strong GHG, and that counts for more than sheer abundance.
So question (1) is; if H2O is a weak GHG compared to CO2; then what is all this crap about H2O being a feedback factor that amplifies CO2 caused warming. We know that more warming of the oceans leads to the escape or lack of take up of CO2 in the oceans; so one could argue that is a positive feedback factor of CO2 cause and effect. Of course any H2O warming of the oceans would lead to the same escape of CO2.
But actually there is very little warming of the oceans due to either CO2 or H2O greenhouse effect; because that long wave Infrared radiation from the warmed atmosphere; whether CO2 or H2O caused, simply warms the top few microns of the surface, and leads mainly to evaporation of more water; along with massive Latent heat cooling of the surface.
Neither one of these things is a “feedback”. Both simply reflect a change in the system parameters from one state to a different state based on some other change.
For example, if you have a mass hanging from a spring, with gravity acting on it to stretch the spring; and you increase that amount of mass, the spring will start to stretcvh further, and that plus the spring compliance will set up an increasing counter force to try and stop the spring from stretching further.
Climatologists would therefore call that a NEGATIVE feedback. The stretching of the spring sets up an opposing force to stop the spring from stretching. Balderdash ! The system is simply readjusting itself from one stanle state to a different state that too is stable so long as the increased mass remains in place.
Same thing with the ocean; if you change its temperature; the equlibrium distribution of both H2O and CO2 in the atmosphere in contact with the surface; will change in accordance with Henry’s Law, in the case of the CO2, and the Clausius-Clapeyron Equation in the case of the H2O vapor. Neither one of these adjustments is a FEEDBACK; and furthermore neither one could care less what it was that caused the ocean surface temperature to change.
but back to Schneider’s rather silly statement that H2O is a weak GHG compared to CO2. Does he dispute the general validity of those absorption spectra for CO2 and H2O that Steve posted above ? Is it not true that H2O absorbs much more of the LWIR energy spectrum than CO2 does; not to mention the absorption of incoming Solar radiation ; where H2O has a very significant absorption (which warms the atmosphere) but CO2 does not (it has some; but nowhere near what water has (molecule for molecule)).
You can’t have it both ways; you can’t proclaim H2O to be a feedback effect that amplifies a weak CO2 atmosphereic warming; and then turn around and call H2O a weak GHG compared to CO2. What’s more both of them are equally permanent constituents of the atmosphere, and H2O virtually always exceeds CO2 even over the most arid of deserts.
There’s one more Venus/Earth CO2 discrepancy, that you should throw into your mix Steve.
Earth mean surface temperature is 288 K which corresponds to a BB radiation spectrum peaking at 10.1 microns. CO2 affects this spectrum mostly due to the 15 micron absorption band of CO2. The next higher energy CO2 band at around 4 microns has little effect on earth since it is less than half of the 10.1 micron peak LWIR spectrum peak; so somewhat less than 1% of theat earth emission acts on the CO2 4 micron line. On the other hand 4 microns is also 8 times the peak of the solar spectrum; so less than 1% of the solar spectrum energy is present beyong that 4 micron line; so the CO2 4 micron line has negligible influence on eather solar insolation or outgoing LWIR.
Now Venus has a surface temperature of 485 deg C (I’ll use you figure Steve); so that is 758 Kelvins compared to Earth’s 288.
So the surface BB spectrum emission from the surface of Venus would be expected to lie at 288/758 x 10.1 microns; whchi is 3.84 microns.
So the earth inactive 4 micron CO2 line is the principal active line on Venus; whereas the 15 micron bending mode line is at 3.9 times the wavelength of the Venus surface emission; and only about 6-7% of the Venus surface emission lies at 15 microns or longer.
For Earth to go Venus, due to CO2, the temperature would have to somehow travel through a region where the CO2 absorptance was less than 10% of the peak LWIR emission, and somehow get hot enough to activate the Venus 4 micron line of CO2.
Ain’t gonna happen; no way; well no way under current general earth orbiat and othe major conditions. Anthropogenics isn’t going to do it.
How about those clouds on Venus Steve; they certainly aren’t H2O; and how could they be CO2 at those temperatures. Aren’t they due to some sulphurous component of the Venus atmosphere?
A couple additional points. The radiation chart atop this page shows black, blue, and lavender black-body curves for earth at roughly our min to max temperature. Venus’ curve will be shifted significantly left due to the 400+ degree hotter surface. That affects the CO2 absorption, shifting from the fat band up to the narrower bands.
The clouds may be transparent to some regions of IR. However, the very depth of the cloud cover could negate that, and produce effects of its own that alter the adiabatic lapse rate. Without weather, Venus should have a much simpler atmospheric model, but one very different due to its composition.
Both Venus and Mars have CO2 atmospheres, but at opposite extremes to what Earth is used to. I don’t see how either of them can be useful to the AGW case.