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
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Here are a couple other links when we covered this 2 1/2 months ago at
http://wattsupwiththat.com/2010/02/22/bill-oreilly-hosts-bill-nye-the-science-guy-and-accu-weathers-joe-bastardi-in-fox-news-debate/#comment-325845
Julian Braggins (01:37:34) :
Ah, very good. I was going to say that too, but figured I’d see if someone else did already. The WUWT readership seems to be big enough so I don’t have to read everything any more to make sure my point of view or factoid gets heard. Maybe I can break my addiction to WUWT now!
Links to Venus atmospheric profiles:
http://www.esa.int/esaSC/SEM5A373R8F_index_1.html
http://www.datasync.com/~rsf1/vel/1918vpt.htm
Warning: the second one is a bit weird. Okay, more than a bit weird. However, the graphs are easy to read.
Misconception Number 1: That CO2 forcing is logarithmic at very high concentrations.
Reality: At very low concentrations CO2 forcing is linear. It becomes logarithmic when saturation of the central absorption line is reached, and increased forcing depends on the wings of the lines (and pressure broadening). However, as concentrations continue to increase, minor absorption lines become sufficiently important in comparison to the wings of the major lines that the increased absorption of CO2 is mostly dependent on the minor lines, and the forcing of CO2 increases linearly with concentration again.
Misconception 2: Lack of Energy Balance thinking.
Two examples have been presented: 1: Titan, despite high pressures, is very cold. A similar thought experiment would be what would happen to Venus if we turned the Sun off – I hope the obvious answer would be that Venus’ temperature would quickly drop to whatever could be supported by internal tectonic/volcanic heating (which wouldn’t be much).
2: Venus with a totally transparent atmosphere: the surface would radiate directly to space. As Nick Stokes pointed out, in such a case, in equilibrium the radiation out from the surface CANNOT be larger than the radiation the surface receives (plus any internal heating): therefore, it doesn’t matter how many atmospheres of the perfectly transparent gas there are, the surface temperature will be solely determined by that radiation.
A simple example of GHG forcing experienced in daily life: humid nights compared to dry nights: humid nights are warm, dry nights are cold. This has nothing to do with temperature, and a lot to do with outgoing radiation and GHG absorption (in this case, water vapor). (it is even more obvious with clouds, but clouds are sufficiently different from a gas that it isn’t as clean a comparison).
-Dave
I found this: “Even though a large percentage of heat radiation is reflected from the top of the clouds and never reaches the surface of the planet, the heat that does penetrate is captured by the thick cloud covering. Less than half of the infrared radiation is released back to space. the effect is to raise the temperature of the planet by a massive 500°C (900°F).” http://www.planetsalive.com/?planet=Venus&tab=B
Steve,
Much of what you stated is right. The comment that failed was to say that the 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” was completely wrong. Later you qualified this by using the statement: “if 90% of the CO2 in Venus atmosphere was replaced by Nitrogen, it would change temperatures there by only a few tens of degrees”. That last statement is correct. However if there were no CO2 or clouds (or other greenhouse gasses), the average surface temperature would only be ~55 degrees C or less (depending on albedo). The lapse rate due to adiabatic expansion at altitude would still hold but the only source of atmospheric heating would then be surface conduction and convection up, which would then eventually spread through the atmosphere. This makes the first quote correct, although somewhat misleading, as your second quote is also correct.
Mr. Goddard shows here how little he understands about planetology. On its face, yes, the “greenhouse effect” is not responsible for Venus’s temeperature at present. But this is complete buffoonery, akin to saying that a person lives a tax-free existence every moment he or she isn’t being handed a paycheck with taxes removed, and then going on to calculate that 99% of American citizens go untaxed 90% of the time. It is not only incorrect, but it shows a complete misunderstanding of process.
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. The “runaway” part, then, is not isolated to CO2 but involves how other consitiuents of the atmosphere respond to this initial increase in heat.
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. In fact, it likely started out quite similar to Earth’s early atmosphere, with no free oxygen, heavy in nitrogen with a smattering of CO2 and a decent amount of water and water vapor and nearly identical surface pressure (governed by the planet’s nearly identical mass and gravity). 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. As a result, hydrogen was separated from oxygen by ultraviolet light and lost to space, and the free oxygen quickly bound to plentiful carbon to make CO2. In this way, all of the planet’s water started being converted to CO2. Suddenly, this “greenhouse effect” vaporized more water, which meant it was vulnerable to UV disassociatio, and yet more CO2 was created, which warmed the surface even further, vaporizing more water, which was in turn disassociated and turned to CO2…. a runaway effect. At the end, we have a Venus as we know it today – completely devoid of water with an absolutely incredible surface temperature and pressure. The hellish end-result of a runaway “greenhouse effect.”
So, as a planetary geologist myself, I can only assume that Steve Goddard is aware of all of this and intentionally attempting to mislead his readers with this ridiculous and simultaneously well-researched farce. I can’t see how he could possibly have researched enough to produce the information he did about atmospheres and chemistry yet somehow manage to miss all information learned during the past 40 years about the history of the specific planet he alleges to describe. Either way, the production of this sort of catchy misinformation is why the US falls farther against other nations in science and innovation each year.
If you’re really interested, read a book, not a blog, people. I can suggest quite a few if you’re interested in how planetary atmospheres really work.
Steven Goddard:
“Smokey
There is essentially no difference in surface temperature between the day and night sides of Venus.”
I didn’t say there was, but from Willis’ link to Dr Hartwig Volz: “Day temperature at 65 km is about 300 K, night temperature slightly below 200 K…”
I don’t know if there’s a difference, myself. And I understand that 65 km is not the same as surface temps. Just commenting on it, that’s all.
I was all set to edit the Wiki, but then I saw the reference which is a Nasa Ames thing:
Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus
James F. Kasting
Space Science Division 245-3, NASA Ames Research Center, Moffet Field, California 94035, USA
Received 12 March 1987; revised 17 September 1987. Available online 26 October 2002.
Abstract:
A one-dimensional climate model is used to study the response of an Earth-like atmosphere to large increases in solar flux. For fully saturated, cloud-free conditions, the critical solar flux at which a runaway greenhouse occurs, that is, the oceans evaporate entirely, is found to be 1.4 times the present flux at Earth’s orbit (S0). This value is close to the flux expected at Venus’ orbit early in solar system history. It is nearly independent of the amount of CO2 present in the atmosphere, but is sensitive to the H2O absorption coefficient in the 8- to 12-μm window region. Clouds should tend to depress the surface temperature on a warm, moist planet; thus, Venus may originally have had oceans if its initial water endowment was close to that of Earth. It lost them early in its history, however, because of rapid photodissociation of water vapor followed by escape of hydrogen to space. The critical solar flux above which water is rapidly lost could be as low as 1.1S0. The surface temperature of a runaway greenhouse atmosphere containing a full ocean’s worth of water would have been in excess of 1500°K—above the solidus for silicate rocks. The presence of such a steam atmosphere during accretion may have significantly influenced the early thermal evolution of both Earth and Venus.
I don’t know enough to have an opinion, but to take the language out of the Wikipedia entry, I’d need some points that rebut that specific source.
Stevengoddard,
Thanks for your stimulating article!
With an Average temperature: 737 K (464 C) it has left me decadaly incredulous that it could be as a sole consequence of a greenhouse effect. However, I think it has to be part of the story from the following considerations:
1) A Soviet probe (s?) reported surprising brightness in visible light at the surface, including good quality photos. (Although there was some argument that they could not be genuine photos because of pronounced shadows around the rocks)
2) Regardless of the source of the energy, at 737K there would be significantly greater radiation from the surface compared with Earth, (as a consequence of T to the fourth power; moving towards near infrared in the Planck curve)
3) The CO2 at ~90 bars is not alone in high absorption capability. The PPMV of H2O at 20 is low percentage wise, but when amplified by 90 bars, that becomes significant.
4) Although ~40% of sunlight is near infrared, this appears to be absorbed high in the atmosphere, above around 60Km, as evidenced by diurnal variations; see below. This would have the effect of reducing the T gradient between the surface and the mid or upper atmosphere, which would slow heat escape a little. (See links below in item 9)
Other stuff:
5) If there is an internal heat source within Venus, (like on Earth), with such a high surface T and maybe an insulation effect of very dense high specific heat CO2, the rapid fall-off of underground temperature towards the surface as seen on Earth would be less pronounced. (also no H20 oceans with evaporative cooling)
6) One of the Soviet probes was reported to have picked-up unusual methane, part way through descent, that was suggested to have been a volcano plume.
7) Although currently reported as dormant, there is agreement on past volcanic activity
8) Khiel and Trenberth/IPCC have claimed that the greatest heat loss from the surface on Earth is from evapo-transpiration, which cannot occur on Venus.
9) This study shows that the temperature in the atmosphere is a nice comfortable 20C at 54 Km. Here’s something interesting and more recent from ESA.
10) There is even less known about Venus than there is of Earth, and I guess the dynamics in the atmosphere are largely speculative.
Pamela Gray
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.>>
My experience has been that an ultralight rod that short will frequently snap under the pressure of even a small trout, just not worth the aggrevation. Go with the length you want but in a stiffer rod. Put a thick rubber band between the leader and your rig to absorb the shock of the trout’s strike. The combination will give you the feel of a light rod in the length you are after and will stand up to a lot more punishment than the ultralight. You can even go down to about 5 feet to get the weight down and still have a very responsive set up. I know this is off topic but all that hyperventilating is messing with your CO2 blood index and we don’t want you over heating, you might be the tipping point!
Willis,
Volz makes the point, correctly, that effective thermal emission to space happens at a higher level of the atmosphere, and the adiabatic heat transport (dry adiabat) would produce a surface heat increment beyond that. That’s true – the greenhouse effect on Earth works somewhat similarly.
The dry adiabat creates a temperature difference, but is not a heat source. Consequently the actual temp is determines by some radiative balance requirement at a point where effective emission happens. On Earth, that is part surface (at ~290K, for atmospheric window frequencies), and part TOA (at ~225K, for GHG absorption.emission frequencies), and of course, some in between. The nett result is IR emission at the effective no-GHG temp of 255K, but with a warmer surface.
So you could say that Volz is arguing for a reduced GH effect, in that some mid-layer of the atmosphere acts like our ground surface, and below that there is little nett flux, and adiabat heat amplification. The IR is still part-blocked by the atmosphere, but by clouds, not GHG.
All true, and known – to work out what it really means, you have to identify the level of that effective layer, which Volz hasn’t done with any great precision.
So to qualify my earlier remark – you can’t have 700K on the surface with an IR-transparent atmosphere. You could get a high temperature from cloud blocking plus adiabat, even without selective IR absorption. You can also get it from a greenhouse effect, and there’s lots of GHG for that. Both effects seem to be at work here.
The “snowball Venus” temp, allowing for albedo, is about 390K. As with Earth, if you found that the outgoing IR spectrum corresponded to a BB that temp, you could say there was no greenhouse effect. I don’t have the information here, but I believe that, as with Earth, it is segmented into different regions of different apparent temperature.
I don’t think the supercritical fluid issue affects the IR considerations, except maybe by increasing opacity. Volz’ notion is that nett IR flux at low levels is zero or small. It probably reduces the adiabat gradient.
CodeTech says:
May 6, 2010 at 5:41 pm
Umm, I have doubts about some of the packing existing energy idea. I use the more technical description that compressing a gas requires adding energy (force x distance) and that’s what is converted to heat. (Springs don’t heat up because they store the energy in the strain in the spring, gasses accelerate as their molecules bounce off the compressing surface.)
You can give someone a good floor bicycle tire pump and tell them to pump up a car’s tire – that gives people a good idea of how much energy is stored in the compressed air!
Shucks, I guess no “radiation cartoons” for Fiji are forthcoming. It seems that the cartoons only work for “average” conditions?” What is really disconcerting is the silence on this subject. Can someone please put me in my place? LOL.
“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. Once all the water in the ocean has been transformed into atmosphere the temperatures will be high enough to start the outgassing of rocks wich raises the temperature and pressure even further. Eventually Earth would look like Venus with a high pressure and CO2 rich atmosphere.”
There isn’t enough [known] CO2 on earth.
Water vapor can not build up unless it’s over 100 C everywhere on earth.
There is enough carbon on earth but there isn’t enough oxygen to combine with the carbon to make say more than 4 atm of CO2.
If you split all the water in our oceans you would have enough oxygen. Or if were to somehow get the oxygen from rock on the the Earth surface there is also more than enough oxygen. Though “somehow” getting the oxygen from the water from the ocean seems easier than getting it from the earth’s crust.
So it’s more than two things- you also need to find or somehow make vast amounts of CO2- of the scale of roughly the mass of our oceans.
Basically I would say it’s too late to make earth into Venus- life has irreversibly shunned us from that little piece of heaven.
you don’t think it may have something to do with the fact that there are two phase transitions within Earths day/night temperature cycle?
Pump heat into the Earth during the day and you convert water from liquid to gas, and increase the air pressure. At night the gaseous water is converted into liquid water, dropping pressure.
Astrowright,
The present hot temperature of Venus is due to a combination of greenhouse gasses, clouds, and large atmospheric pressure. It would only take a relatively small fraction of greenhouse gasses at at the high surface pressure to make the radiation to space occur mainly at the outer edge of the atmosphere. The upper atmosphere temperature is determined by how much energy is absorbed by the atmosphere, surface, and clouds, and increases downward due to the adiabatic pressure increase effect. Even if there were only 1% CO2 and 99% Nitrogen, there would be little difference in surface temperature from the present. If there were 100% Nitrogen, the surface would be closer to Earth temperature (but with a hot side and cold side due to slow rotation). The thermal capacity of the CO2 is not important, its absorption of long wave radiation is.
Goddard: If you are gonna make this kind of post, I think you owe me an answer for my comment at : May 6, 2010 at 3:58 pm:
Just what is your take on the “greenhouse effect?”
Bob_FJ
There is no question that absorption of IR by greenhouse gases elevates the temperature on Venus. My point is that it doesn’t explain the very high temperatures, and particularly on the dark side of the planet.
I have been waiting for the appropriate time to post this NASA link. You have to read to near the end for the AGW propaganda. There is a slight change from the last time I looked at this (a week or so ago.) One of the byline authors name has been removed, probably the source of the moonbattery. It was for someone at that Arctic Ice Institute thingy of NASAs ( can’t remember the exact name). What she was doing writing up a piece about Venus is anyone’s guess. The NASA editors must have thought it looked suspicious, so removed her name.
http://www.nasa.gov/topics/solarsystem/features/magellan20100408.html
astrowright,
Please finish the excellent explanation of Venus and go on to explain that we on Earth are no where close to even being able to cause a similar fate on our home world.
Atmospheres are NOT static. It is constantly mixed by vertical and horizontal air currents, so that the energy content of one mole(6.023X10^23 molecules of gas) at 10,000 feet altitude is ~= to the energy content of one mole of atmosphere at sea level. When compressed the gas does not gain energy; the molecules merely strike each other more frequently, so the measured temperature goes up. No gain or loss of energy. These air currents also prevent the heavier molecules from drifting down so that we have a well mixed atmosphere at most levels.
Since Venus atmosphere is also well mixed, it too must have air currents to mix the air in both content and and molecular energy, so adiobatic warming will take place.
I question the extra atmosphere pressure as a reason for highVenus temps.
p1v1/t1 = p2v2/t2. plug in p1, v1, t1 =1, and you get
1*1/1 now put in a p2 of 90, a v2 of 1/90, and a t2 of 1, you still get 1. Nfr above got it right when he mentioned spectrum broadening. For more on that, look up “Voigt Profile”
Ric Werme
May 6, 2010 at 7:37 pm
You are goofy wrong. PVT, its simple physics, the basic gas laws, sheesh! Don’t they teach simple science in school any more? No wonder the greenies can promote their nonsense.
Actually Jonas, I had come to the same conclusions as cited in this post quite a long time ago while arguing about this with my father. Interestingly, after a considerable amount of Internet research, I have found a plethora of information across the web on this subject. Quite a large volume of information, even information gained from NASA websites, corroborates precisely what Steve has written here.
If you do a little research and gather the FACTS about Venus, and then apply a little dose of Occam’s razor:
The only plausible conclusion is again, precisely what Steve has illustrated here. Just do a little bit of “real” research and you will find this for yourself. It is undeniable.
– Cheers
“If I remember my basic physics: energy absorbed is an inverse square to the distance from the source. Mercury has no atmosphere, and I’ll bet it’s sunny side is a lot hotter than Venus.”
It isn’t.
Mercury:
Maximum surface temperature: 427°C
Minimum surface temperature -173°C
Venus:
Mean surface temperature 482°C
http://www.solarviews.com/eng/homepage.htm
So Venus is hotter and has a higher average temperature [whatever that means].
Of course you comparing apples to oranges. On Mercury the temperature is the surface temperature and venus is temperature is air temperature- though the Venus air would warm the ground to that temperature.
If Venus had an airless moon, obviously it’s surface temperature would be cooler than Mercury. If you gave Mercury a 1 atm of atmosphere [of whatever gas] you would get a lot of wind. The wind would so vicious it’s would beyond the minds of humans to grasp. And I suppose it would hotter, though the dust would make it quite dark on the ground.
While you’re all debating what is keeping Venus so warm, here on Earth, Arctic sea ice is now below the levels of both 2008 & 2009 for this same date according to JAXA…