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
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If Venus is hot because of the atmospheric pressure, Jupiter, Saturn, Neptune, and Uranu should be warmer shouldn’t they??
Venus is hot because it is either younger than the consensus claims, or had a relatively recent catastrophic impact.
They have found that Mercury has more atmosphere and is hotter than it should be based on their consensus science also. I don’t think atmospheric pressure enters into it there either.
@ur momisugly Duster says: May 6, 2010 at 12:19 pm
This agrees with the conclusions of Gerhard Gerlich (2007) Falsi cation Of
The Atmospheric CO2 Greenhouse Eff ects Within The Frame Of Physics of the Institut für Mathematische Physik in Braunschweig, Germany. It is 114 pages and refutes, from a Physicist’s point of view, the concept just as Nahle asserts: It is the hindrance of convection which heats the greenhouse, not radiation.
The math and the laws of physics Gerlich goes into are over my head, so I can’t myself claim to know one way or another.
But I’ve been waiting to post this link for a LONG time, because Sagan was wrong, and I wanted to have a venue for directing people to it. See my next comment somewhere below…
Great article.
For those asking about Earth’s pressure increasing in the future, that won’t happen. In fact, when Earth was young, the atmosphere was about 50 times as dense as it is at present. Largely made up of CO2. The sun was about 40% dimmer than at present.
Where did all that atmosphere go? Into the rocks. The marble, limestone, and other carbonates that make up large portions of our continental plates were created by life forms sequestering that CO2 in the atmosphere as rock, as well as acidic rainfall that reacted with volcanic, igneous, and sedimentary rocks to create carbonates. All that CO2 is permanently sequestered there. A smaller amount of that former CO2 is sequestered in coal, oil, and natural gas deposits as well as methane hydrate deposits under the sea bottoms. When we burn fossil fuels, we free up that CO2 to be resequestered as more permanent rock by corals as well as acid rain weathering rocks.
The Ice Ages we’ve experienced in the last several million years are a harbinger of permanent end of life on Earth. The interglacials have only been temporary interludes that enabled life to extract more CO2 from the landscape and sequester more of it as rock. Until and unless there is a major volcanic intrusion into fossil fuel deposits (for instance, an eruption of Yellowstone caldera intruding into coal and oil shale deposits elsewhere in Wyoming), the only force putting sequestered CO2 back into the atmosphere to keep life going on Earth is mankind.
rbateman says:
May 6, 2010 at 2:42 pm
How did Venus get such a dense atmosphere? It heated up over time to the point where all of it’s Carbon, Oxygen and Sulfur volatilized. No magnetic field means it lost it’s Hydrogen early on.
Why didn’t Earth do that?
It has life which aids in sequestering the elements that would lead to a denser atmosphere. a magnetic field which keeps the Solar wind from blowing away the lighter elements, and vulcanism to keep it regenerated.
Mars froze out because it has no magnetic field and no vulcanism.
The question is: Why does Venus still have vulcanism?
r, doesn’t distance from the sun have something to do with temps on Venus and Mars?
How did such poor science come to be common knowledge??
Ask our Venus probe modeler and physicist, who is in charge of GISS and thinks coal trains are the same as Holocaust Trains in the Third Reich, James Hansen!!!
HAHAHAHAHAHAHAHAHAHAHAHAHAHA
Dennis Wingo says:
May 6, 2010 at 3:22 pm
“The spectral absorption characteristics of CO2 are also pressure dependent. If you have an atmosphere that much more dense than the Earth, the “wings” of the absorption bands are much wider and taller.”
So Dennis, how about a little quantitative information, how much wider, how much taller? If you integrate the curve, do you really get a lot of area, or maybe just a slight spreading, but these are the tails of the absorption bands, and so how much matters a lot.
Sounds like more PNS to me.
“…Venus is hot because it was recently formed.”
Despite my earlier linking to a Velikovsky fan page, I don’t think the science shows he was correct. It would be more accurate to say that Venus is hot because its *surface* was recently formed (in geological timescales). Surface cratering (or lack thereof)indicates a very young surface. Due to the lack of tectonic activity (which allows gradual heat loss on Earth) the planet is believed to have been entirely molten within the last five hundred million years.
“PJF says:
May 6, 2010 at 12:08 pm
It would be interesting to know what the atmospheric temperature on Venus is at the height equivalent to one Earth atmospheric pressure.”
One commenter on another thread at some other time had said it was within 1-2 deg C of Earths temperature. Sounded like he knew what he was ralking about, and it makes sense.
Heck, even the temperature of the earth at increasing depth and higher pressure increases, it reaches over 100 deg C where water boils at 300 deg C, so obviously at a pressure of 92 atmospheres it’s going to be hot. CO2 does make it hotter though, since I would expect some mixing of the atmosphere from top to bottom
For some reason, deep ocean temperatures 2.5-5 miles deep is only 3 deg C and does not increase. But who knows, if NASA and their scientists can lie (distort) about the cause of the temperature on Venus surface, maybe this is not true as well. Maybe that’s the corrected temperature after adjusting for pressure, like they do with the atmosphere where the potential temperature (corrected for lower pressure and lapse rate) is much higher than the actual temperature (down to -100 deg C)
Yes, To compare the surface temperature of Venus to the Surface temperature of Jupiter you would have to go down about 57000km (trough Jupiter’s “Atmosphere” to reach the mostly solid/liquid surface at which point the temperature is as high as 24000K. A good deal warmer than Venus and a bit more pressure too.
Hmmm, aren’t you now agreeing that the atmospheric pressure explains why the Earth’s temperature averages about 16 C, rather than -18? I thought that conventional wisdom says that the greenhouse effect is the reason.
Core size of Venus would have a great deal to do with magnetic field and speed of rotation. No core like the moon is no more rotation. Small core on a big planet would slow faster with the frictional load.
stevengoddard:
Good article.
This substantiates it.
The Venusian atmospheric temperature at the 1000 mb level (about 50 km above the surface) is right around 100 deg F.
Which, considering how much closer Venus is to the sun, is scarcely any different from the Earth’s temperature at sea level.
Ian L. McQueen says:
May 6, 2010 at 3:00 pm
Steve-
Interesting article. But I wonder why the pressure is so high.
* * * * * * * * * * * * * *
I also wondered why the pressure is so high. I found that the mass of the atmosphere of Venus is larger than that of the Earth by a factor of 100. Venus has about ~4.8X10^20kg whereas the Earth has about 5.1X10^18kg. The compression of the gas would be higher with more mass and gravitational attraction, thus the higher pressure. Similarly, the atmosphere of Earth has more mass than the Mars by a factor of 100. Again Earth has about 5.1X10^18kg whereas Mars has about ~2.5X10^16kg. With less compression on Mars, its pressure would be less than the Earth’s pressure.
Warren
Is La Nina about to arrive?
http://www.osdpd.noaa.gov/data/sst/anomaly/2010/anomnight.5.6.2010.gif
Chad Woodburn says:
May 6, 2010 at 2:12 pm
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?
________________________________________________________________________
Take a look at the graph in the post. The red curve is the incoming solar radiation and the blue curve is the energy bouncing off the earth’s surface as transmitted by the atmosphere. The purple, blue and black lines are the radiation transmitted from the earth into space; they are calculated using a blackbox assumption based on temperature. The 3 lines represent 3 different temperatures from 210–310 K (–63 to +37 °C) due to the variation of the surface and atmospheric temperature over the earth. The blue area is what escapes into space. Next look at the gray curves. The third one down is CO2. The absorption bands are not in the solar energy curve area except for one. Also note by looking at the top curve that ALL the energy bouncing off the earth’s surface has already been absorbed in the CO2 absorption bands. (that is the logrithmic thingy Steve is talking about) There is a bit of room left at 2um but that is in the sun’s part of the spectra. Adding CO2 is not going to do a darn thing.
One look at that graph convinced me (a chemist) this was nothing but a political money making scheme. If the CO2 already in the atmosphere has already absorbed all the radiation adding more CO2 just isn’t going to matter much. There is a convoluted explanation about one molecule re-radiating and the additional molecules absorbing the same energy a second and third time. However think about it. The actual curve shows the energy is not getting transmitted from the atmosphere at those wavelengths at all. How can more CO2 effect that blue curve???
It is not quite as simple as that. Here is one explanation http://www.udel.edu/Geography/DeLiberty/Geog474/geog474_energy_interact.html
And the other side of the debate: http://landshape.org/dokuwiki/doku.php?id=introduction
Hope that helps.
I tried to comment, but no show. Try again:
“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.”
Hmmm, are you saying that the reason the Earth’s avg. temp. is something like 17 C, instead of -18 is because of atmospheric pressure? The experts keep telling me that the difference is due to the greenhouse effect!
Could the pressure be an effect of the heat rather than the heat being caused by the temperature?
With regards to Jupiter, wikipedia says: ” The amount of heat produced inside the planet is nearly equal to the total solar radiation it receives.[26] This additional heat radiation is generated by the Kelvin-Helmholtz mechanism through adiabatic contraction. This process results in the planet shrinking by about 2 cm each year.[27] When it was first formed, Jupiter was much hotter and was about twice its current diameter”
There’s no mention of pressure itself generating heat, only absorbed solar radiation and heat generated through the planet shrinking.
Steve Goddard,
Great post.
Every small debunking of nonsensical horse**** helps.
So te ultimate solution to CAGW is to liquify a bunch of the Earth’s atmosphere and lower the atmospheric pressure!
Pressure and temperature are dependent only in a constrained adiabatic system. For black box systems like planets, temperature is independent of pressure because heat is freely exchanged. Venus’s albedo likely pertains more to visible light than heat; I expect the opaque atmosphere absorbs most impinged solar heat. Venus receives 2x the solar radiation intensity as Earth, and its temperature (K) is about 3x; the excess 50% probably retained by atmospheric opacity. It just takes the heat a bit longer to escape. Superpressurized CO2 may play a big role in that, but Earth has nothing like that, and never can.
The temperature profile on Venus stays very close to the adiabatic lapse rate of CO2, which has nothing to do with IR radiation, just the coefficient of specific heat and constant pressure. In Carl Sagan’s 1967 paper on the surface temperature of Venus, prior to any measurments of it, he got it right to within 50C or so just based on the cloud top temperature and the depth of the atmosphere. He also showed that the surface temperature would be hotter if the atmosphere was nitrogen instead of CO2, due to the differing coefficient of specific heat at constant pressure.
The EPA Endangerment Finding Comment Response contains a relevant comment on this question about pressure:
Comment (3-49):
A commenter (2210.1) states that Venus is not an example of the greenhouse effect but is merely warmer because it is closer to the sun. Another commenter (2210.5) attributes Venus’ warmth to higher atmospheric pressure because compression causes temperature increases (for example, this occurs when inflating a bicycle tire, due to the proportional relationship between pressure and temperature represented in the ideal gas law, pV=nRT, i.e., pressure times volume equals amount of gas times temperature times a constant), and that a 95% CO2 atmosphere is actually cooler than a 100% biatomic atmosphere would be.
Response (3-49):
Venus is warmer than the Earth both because of the greenhouse effect and because of its distance to the sun; in contrast, Mercury is cooler than Venus despite being even closer to the sun. Were Venus’ atmosphere to be transparent to radiation, then the surface temperature of Venus would be determined only by the blackbody radiation of the surface, and the pressure of the atmosphere would not change this equilibrium temperature. There is a large body of literature on Venus’ climate; one example is Bullock and Grinspoon (2001)—all of which show that CO2 is a significant contributor to the planet’s warmth. Because volume is not held constant, it is not appropriate to use the ideal gas law to determine the temperature on the surface of Venus based only on knowledge about its pressure. Therefore, the scientific literature shows clearly that the temperature of Venus is an example of a greenhouse effect, in contrast to the assertion by the commenters.”
Almost exactly ten years ago, Dr. Hartwig Volz made what I think is the best analysis of this on the late and greatly missed John Daly’s website. His analysis is here. By and large it agrees with what Steve Goddard says, only with more detail, more math, and a curious twist.
The twist is that on the surface of Venus, CO2 is no longer a gas but a “supercritical fluid”, which behaves very differently than a gas.
In any case, another excellent post, Steve.
Dennis Nikols says: May 6, 2010 at 12:20 pm
We know them as Sagan and Velikovsky.
In Worlds In Collision (1950), Velikovsky asserted that the surface temperature of Venus would be found to be between 800F and 900F. Velikovsky set off such a absolutely thunderous reaction among astronomers that they threatened the publishers, Macmillan, which published many school textbooks, with being blackballed if they didn’t cease and desist. Macmillan capitulated, even though the book was #1 on the best sellers list. Doubleday took over the publishing.
Be it known that the consensus (ever had of that term?) in 1950 was that Venus’ surface temperature was approximately 200F-300F. It was one of the reasons the astronomers were so furious with Velikovsky.
While I completely disagree with Velikovsky’s mechanism, a few of his observations and piecing of facts have subsequently been seen to hold water. But I disagree with the scientists and their reaction even more than I disagree with Velikovsky.
A latecomer to the brouhaha was Carl Sagan. When in 1962 the NASA Mariner probe flew by Venus and determined that the surface temperature was approximately 428C (802F), the LAST thing the astronomers were going to do was admit that Velikovsky (whose book, combined with the UFO furor of the late 1940s and early 1950s, started the Hollywood era of catastrophes from space) was correct. They had to come up with an explanation, and they had to do it NOW.
Along came Sagan and his runaway greenhouse speculation.
It is a constant of scientists that when they run across something they can’t explain – but they can’t deny, either – they throw out a speculation and then turn on their heels and exit, stage right, leaving everyone to assume that, since the scientist has now spoken, the issue is settled.
The world as assumed ever since that since Lord Sagan hath spoken, that what came from out his mouth must be true. The runaway greenhouse effect went down in the records as THE truth about Venus. Hell, they needed SOMETHING. Otherwise they would have to have admitted that Velikovsky might have been right – which would mean that they were wrong. Heaven forbid.
It was similar to the period in the early 1800s when scientists finally could put the beliefs in Noah’s Flood to rest. Noah’s Flood – the last bastion of religion which science had not been able to bury – had all the evidence going for it. All round, everywhere, there was well-documented evidence of a great catastrophe – striated rocks; overturned layering of the earth; erratic boulders on top of the Alps and other high peaks; foothills made up almost entirely of mammoth; elephant, hippopotamus and rhinoceros bones (in the Arctic Ocean), caves filled with the shattered bones (100%, BTW) of every sort of animals, both prey and predator. Then along came Agassiz and Lyell and then Darwin, to provide a framework that allowed for Ice Ages and seemingly limitless eons for the changes that had appeared to Cuvier and his predecessors as diluvian, meaning flood-caused. The Bible was overthrown by geologic ages.
But then 100 years later, along came Velikovsky, whose efforts threatened to let the beast of the Bible back into the discussion. And even though Velikovsky’s work was related to accounts in religious writings, it had nothing religious about it. But they couldn’t let even a hint (deny the decline) that there was anything but slow Uniformitarianism and Darwin’s survival of the fittest. So Velikovsky had to be destroyed in 1950 – even as the world was listening to him. And then in 1962, Velikovsky had to be dstroyed again. He had to be trumped by scientists, so that he couldn’t claim that manna hadn’t fallen from the sky (a literal claim in Worlds In Collision). That was WAY too close to bringing religion back.
Sagan’s speculative runaway greenhouse effect saved the day. The scientists could turn on their heel, exit left, and leave everyone assuming that St Carl had saved the day.
It was left to another decade and one James Hansen to really put the greenhouse effect – the one that hadn’t YET runaway, BUT THAT MIGHT! – together with Arrhenius’s CO2 concern (at a time when it was aerosols in the form of coal dust that was the real issue) and VOILA! BE SCARED! BE VERY SCARED!
Sagan took a 96.5% CO2 Venus atmosphere, and he made assumptions. That became a dogma.
Then that dogma was taken by Hansen to apply to Earth’s atmosphere, which was only 0.3% CO2 – 320 times less – and created another dogma. We had dogma-squared, and without any science behind it. The greenhouse mechanism was assumed to be real, because SAGAN said it was real.
I’ve been screaming about this for three decades now. I am SO happy to see someone else questioning it.
Velikovksy WAS right, but for the wrong reasons.
Sagan was WRONG, but – in his mind – for the right reasons.
Hansen was WRONG, and for the wrong reasons.
P.S. Velikovsky’s other main book, Earth In Upheaval delineates MUCH that argues against Uniformitarianism. So did Comet Shoemaker-Levy’s impacts on Jupiter in 1994. Only after that did science wake up to the real possibility of catastrophic events in the time of man – which was Velikovky’s main point in the first place. Since 1994, not one nouveau-catastrophist has credited any of their plagiarized concepts to their father, Immanuel Velikosky. To do so would be to admit that the consensus was wrong for the last half century. But it would also give religion a foot in the door – and well, that will never do…
If Velikovsky was right, what chance would Ice Ages and limitless eons have? Who would stop our schools from teaching all kinds of non-Darwinian things? What would happen to the consensus?
re- kuhnkat says:
May 6, 2010 at 3:32 pm
“If Venus is hot because of the atmospheric pressure, Jupiter, Saturn, Neptune, and Uranu should be warmer shouldn’t they??”
Jupiter is blazin’ hot. Some info on Jupiter-
top of atmosphere is at -145 C
50 km thick layer of clouds, followed by 21000 km of H2, He, transitioning to liquid, followed by 40,000 km of metallic liquid H2, followed by possible solid rocky core (surface).
Surface pressure of several million atmospheres.
Surface temperature estimated at 24,000 – 30,000 C. Nowhere near the Gorian crustal Earth temperature of a few million degrees (C, F, K, R, take your pick), but still pretty hot.
Adiabatic lapse rate of Jovian atmosphere is about 2 C/km.
Earth is 6 – 10 C/km.
Venus is 10 C/km.
Mars is 4.5 C/km.
Steve Goddard is simply repeating the standard lapse rate calculation, given for adiabatic case as Gamma=g/Cp, where g is gravitational constant and Cp is the specific heat of the atmosphere.
If you want a runaway Greenhouse here on Earth, you need to somehow boost the atmospheric pressure by a factor of 20 or more. Good luck with that.
Its simply stunning that Venusian expert Hansen continues to spout runaway Greenhouse drivel due to anthro emissions as being remotely possible here on Earth.