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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Steve Goddard,
My previous comments are not clear enough. The lapse rate (drop in atmospheric temperature with increasing altitude) due to the very high surface pressure on Venus would exist with a greenhouse atmosphere or one totally transparent to both incoming light and outgoing long wave radiation. The greenhouse gas as you pointed out does only cause a few degree effect directly. However, without a greenhouse gas, the surface is where the outgoing radiation has to match the energy of the incoming that was absorbed, and thus this is where the surface temperature is determined. In that case, the lapse rate results in the atmosphere getting very cold as altitude increases. If there is any reasonable amount of greenhouse gas, the location of much of the source of radiation to space moves up in the atmosphere. Even less than 1% CO2 in Venus’s atmosphere results in almost all of the radiated energy to space occurring at very high altitude. Now the added temperature from the CO2 is still small, but the location of the temperature is very high altitude, and the increasing temperature (adiabatic compression) as you go lower still holds. It is the movement of the location of the source of radiation to space from the ground to high altitude along with high pressure that makes the surface hot on Venus, and this is not a runaway effect but straight Physics given the present conditions.
astrowright says:
May 6, 2010 at 7:18 pm (Edit)
Astrowright, a fascinating post. A few questions:
1. You say that in the early days, the atmosphere of Venus was similar to that of the early earth, mostly nitrogen. What evidence is there for that?
2. At present, the atmosphere of Venus contains very little nitrogen (~ 3.5%). What happened to all the early nitrogen?
3. You say that the cause for what you call the “runaway greenhouse effect” is the stronger ionizing radiation at the the top of the Venusian atmosphere. If that is the case, wouldn’t a much more accurate term be the “runaway ionization effect”, and as such, be something that could never happen on earth?
4. You say that the ionizing radiation at the very top of the atmosphere dissociated the water vapor and that the “free oxygen quickly bound to plentiful carbon to make CO2”. Why would carbon be plentiful at the very top of the atmosphere? And why would the oxygen not reform as O2?
5. Why is there still water vapor in the Venusian atmosphere (20 ppmv)? What has prevented the ionization of the last of the water?
Many thanks,
w.
A wonderful and thorough analysis, I cannot find anything in here to disagree with. I think it safe to say that probably 99.999% of the population is quite happy to accept things blindly, simply because a well-known personality says it is so. This is why the Hawkings of the world must be very careful about what they say.
PS
Before the readings of the Venus probes became erratic the pressure/temperature readings were well within normal adiabatic paramaters.
astrowright says:
CO2 is a heat-storing molecule. More CO2 present in a planet’s atmosphere will store more heat as shortwave radiation has a harder time escaping the planet.
Typo there, yah mean long wave radiation o course.
“However, Venus’s slightly closer proximity to the Sun meant that more ionizing radiation was available to disassociate the water vapor in the upper atmosphere.”
And obviously the water vapor on mars suffered a similar fate, so wouldnt the lack of a magnetic field be more of a candidate over location? Considering mars is further from the sun than us. And initially wouldn’t the water vapor feedback, disassociation theory have resulted in an ozone layer? As well with corresponding albedo feedback’s from increased cloud cover from the increased GHG forcings? (id imagine we arnt going to fare to well when our core cools, and our atmosphere gets blasted by plasma. )
End o the day, it is speculation, i see there was a paper printed recently that challenged the traditional early earth faint sun paradox/high atmospheric co2 compensating, with a theory, backed with evidence that atmospheric co2 was low, that cloud cover at the time was greatly reduced, as a result of the absence of life, that it self was responsible for the nuclei creation for cloud formation through biological processes. So if this paper stands up to time, it would also bring into question, whether life it self could be a factor.
I dont think there is anything wrong with the open discussion of competing idea’s, even if i dont agree with them.
Also, I have not heard anyone here mention the fact that Venus has not magnetosphere either. It has NO magnetic shielding from the sun as we do. Any idea how hot Earth might be without a magnetosphere?
Unfortunately, what you have declared so adamantly as fact is, by it’s very nature, what is under dispute currently. In fact, what you have described is, in effect, what the whole argument of global warming is and consequently, people who do not agree that we understand fully the processes by which this plant achieves its temperature balance, are even less than willing to accept that you (or anyone else) can then ascribe said theory – with another planet altogether – and expect to be 100% correct.
I note you were particularly blunt with your critisms and so shall I – I can only assume that the complete lack of uncertainty relating to process we know only partially how they work and arrogance in assuming you do was a result of your Planetary Geology degree being …. honorary?
Pamela Gray says:
May 6, 2010 at 6:57 pm
Wrap your own rod, that’s what I do.
Read about blanks here.
http://www.onorods.com/calhist.htm
Steve,
What a great post.
You got everyone thinking. Bravo!
Willis Eschenbach says:
5. Why is there still water vapor in the Venusian atmosphere (20 ppmv)? What has prevented the ionization of the last of the water?
If the stripping of the water vapor was due lack o magnetic field, and solar winds, the water vapor in the atmosphere would be the result of the resultant thicker atmosphere becoming charged, and acting as a magnetic field itself . And the later vented H2O not being stripped. As id imagine would also be the case with astrowrights hypothesis.
Just thought id throw it out there;-)
Ahhh, Mike, you beat me with a “magnetosphere” topic reply … a good reply and a topic of Venus I would be interested in learning more about.
astrowright
May 6, 2010 at 7:18 pm
One big difference between the Earth and Venus; the Earth has a whopping big atmosphere stripping moon!
@ur momisugly Duster May 6, 2010 at 12:19 pm & Feet2thefire
The problem I have with Professor Nasif Nahle’s work was put forward on another blog (unknown poster), quote:
“This suggests that the atmosphere transers no photons to the surface of the Earth at night. This is not the case, as the flux of longwave radiation from the atmosphere has been measured, and even occurs during the polar night (the months of darkness the occur at the poles each winter). See http://journals.ametsoc.org/doi/full/10.1175/JCLI3525.1
It’s perfectly reasonable to state that at night the surface cools by radiation – that’s true. But if there were no back radiation from the atmosphere, it would cool faster at night! This is not a takedown of AGW – it’s attempting to take down the very notion of a greenhouse effect! (Well, as far as I can tell anyway). “
Sea ice is within 1 SD of the mean. All predictable due to weather. Moving on.
Venus versus Mars. Sounds like a WWF fight. The winner must battle Earth for the belt. Will there be chairs involved?
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.
Troll scratches head….. doesn’t know where to turn…… watches ‘An Inconvenient Truth’….. goes to bed happy….. dreams of dead polar bears and cannibal grandpas….
Pamela Gray
May 6, 2010 at 9:00 pm
Would that be the Asteroid Belt?
Pamela Gray says:
May 6, 2010 at 6:57 pm
Can I have your number Pam? hehe
As many folks have pointed out, your analysis is thoroughly flawed. Some sunlight gets in, but the IR is trapped by the extremely pressure broadened infrared absorption lines. I’m sorry, but the Venus greenhouse effect is real.
This is all over my head, but I’ll point out something anyway:
1) CO2 only absorbs radiation at certain wavelengths. Those wavelengths belong to black bodies below 50 deg C and above 300 deg C. It doesn’t absorb anything in-between.
2) Earth has very few places – outside of the upper atmosphere – at those temperatures, so very little radiation is produced by the earth that is absorbed by CO2.
3) Venus has lots of things at those temperature – including mostly the atmosphere, so CO2 is much more relevant to Venus than to earth.
James
Oops – in previous comment, I meant CO2 obsorbs energy from black bodies below -50 deg C. Not 50C. My bad.
James
astrowright says:
May 6, 2010 at 7:18 pm (Edit)
… Venus has not always had a thick atmosphere, as evidenced by by circumstantial conditions of the early solar system as well as Venus’s geologic history.
And how much of Venus’ geologic history do we have an evidence for? My understanding was that for decades we had about exactly 1 picture of the surface, and only recently have we revealed the entire planet surface through long-range-radar studies. Exactly what evidence on our radar maps and single picture tell us that the atmosphere used to be thin?
About the nitrogen in the atmosphere in venus, its 3.5% of 4.8 × 10^20 kg. On earth its 78.08% of 5 × 10^18 kg.
So guess what, there is even more nitrogen in the atmosphere of Venus then there is in the atmosphere of Earth. In fact there is about 4 times more nitrogen on Venus compared to Earth so i guess it is still there if both atmosphere started out equally, the better question would be, where is our nitrogen?
As for water still being a trace element in the Venusian atmosphere, it has a lot of sulfuric acid and hydrogen sulfide. Carbon Dioxide will split into Carbon Monoxide and Oxygen under UV light, Oxygen reacts with Sulphur to form Sulphuric Trioxide wich then combined with water will lead to Sulphuric acid.
Volcanism (although not yet proven on Venus) could add all the needed gases into the atmosphere. On Earth watervapour is the most abundant gas that comes from vulcanos. That could well be the source for the water on Venus, not much but enough.
Lon Hocker
This article is pointing out that it is pressure, rather than composition which causes Venus to be hot.
You responded with a statement saying that I am wrong, because it is pressure that makes Venus hot.
You might want to think that line of argument through a little bit.
DesertYote says:
May 6, 2010 at 8:17 pm
I am quite aware of the gas laws, thank you, physics was my favorite high school course in 1967/68. Laws say what, they don’t say why. Compress a gas, the temperature goes up. Temperature is a measure of kinetic energy, so something has accelerated the gas molecules. Why is that goofy?
I like physics because it explains how the natural world works. The derivation and meaning behind the equations of motion, gravity, etc are more important to understanding the world than slavishly plugging in numbers into equations.
You might want to check out my web site, I don’t think you’ll find much AGW support there.
Pamela Gray says:
May 6, 2010 at 6:57 pm
No, no, no!!! I’m not talking about a lure spinner. I am taking about the rod. A baitcasting rod has a trigger on it (a place for parts of your hand so you can use other parts to slow down the line as you land that fat worm just where you want it). A spinning rod doesn’t have this thorn like feature under the rod. But most baitcasting rods are made for bass fishing (a fat heavy fish) and are usually made for 8+ pound test weight (think log size girthy rod, not twig size skinny rod). I want an ultralight baitcasting rod (twig size skinny and flexible) with the trigger and I want it to be short (less than 7 ft), not the usual length for such a rod. I want to use 4 to 8 lb test. Any baitcasting rod I have found is too long and too telephone pole stiff for trout.
See???? I am hyperventilating again!!!!! Come on you guys!! You’re GUYS! You should know this stuff!!!!
I’d make my own, it’s easy, you can buy a baitcasting rod butt and it sounds to me like 7′ fly rod blank would work well (try Cabelas). I built myself a 9′ noodle rod for steelhead using 3lb test using a fly blank, the biggest I caught with it was 18 lb. Good luck.
Lon Hocker
One more thing. Please explain how the dark side of Venus (which is dark for months on end) manages to keep the same temperature as the other side of the planet which is light for months on end.
If you can invent a greenhouse which stays as warm at night as it does during the day, you should get very rich.