What temperature would Earth’s surface be without greenhouse gases?

Posted: June 6, 2011 by tallbloke in Astrophysics, climate, Energy, Solar physics, solar system dynamics

This thread is open to all who can stay on topic. Comments containing off topic grandstanding, name calling etc will hit the bottom of the bit bucket. So don’t start bellyaching afterwards. 8)

I came across this webpage which offers a set of calculations which says that without greenhouse gases, Earth’s surface temperature would be about 9 or 10C lower than it is. This is clearly a lot smaller difference than that asserted by the IPCC scientists, who say it would be about 33C lower. They have been known to exaggerate though.

As a side issue of interest, this page says that Mars is cooler than it would be without its carbon dioxide (co2) atmosphere. How does that work? Or is this a clue that the page is just wrong?

If so where is this page incorrect? Or is it the IPCC that is incorrect? How well constrained is the calculation for Earth anyway?

Where are the error bars? 8)

Now this page is obviously a personal effort, and we don’t know who wrote it, so all the usual caveats apply.


Planets have surface temperatures above absolute zero because they exist in the solar system, at the heart of which is the sun which radiates energy from its surface at the rate of:

Ls = 3.86×1026 Watts (or Joules per second)We now need to consider how much of this energy is intercepted by a planet of radius R at a distance r from the Sun.

Solar Radiation to Planet

Consider the hypothetical sphere surrounding the Sun with a radius r and centred on the Sun. The radius of this sphere is the same as the radius of the planetary orbit.

Now all the energy radiated by the Sun has to pass through this hypothetical sphere, which has a surface area of 4 p r2 . Thus the amount of solar energy that passes through an area of one square metre of the sphere is given by the formula:

S = Ls / ( 4 p r2 )

where S is termed the solar constant for that planet. The table below lists the results from this formula for the four terrestrial planets Mercury, Venus, Earth and Mars.

Solar Constants

Mercury 9159 W/m2
Venus 2623 W/m2
Earth 1373 W/m2
Mars 591 W/m2

The total energy that is intercepted by the planet is the solar constant times the projected area that the planet presents to the solar radiation. This is essentially the area of the planetary disc which is p R2. Thus the energy input to the planet is given by the formula:

Ein = S p R2

Now this energy input is balanced by the energy that the planet radiates back out into space. The energy radiated by an ideal (black-body radiator) planet with no atmosphere is given by the Stefan-Boltzmann equation:

Eout = s A T4

where A is the area of the planet that contributes to the reradiation of the energy, and T is the mean temperature of that surface area. If the planet is not rotating, then the only area that radiates any significant energy is the hemisphere that faces the sun. However, if the planet rotates with a reasonably short period, then the energy received from the sun will be distributed over the entire surface area of the planet, and the entire globe will thus participate in the reradiation of energy back out into space. This area is given by A = 4 p R2. By equating the energy radiated out into space to the input energy received from the sun, we can obtain an expression for the mean temperature of the planetary surface. This temperature is given by:

T = { Ls / ( 16 p s r2 ) }1/4

It is interesting to note that this temperature depends only upon the distance of the planet from the Sun and not upon the size of the planet. The table below lists the mean planetary temperatures expected for the four terrestrial planets if they had no atmosphere, were ideal radiators and were rotating with a period measured in no more than a few tens of hours.

Computed Mean Planetary Temperatures

Mercury 448 K (175 C)
Venus 328 K (55 C)
Earth 279 K ( 6 C)
Mars 226 K (-47 C)

Deviations of actual planetary surface temperatures from these computed temperatures are due to:

  • Inadequate planetary rotation
  • Non black-body radiator (radiation efficieny <>1) or high albedo
  • Presence of an atmosphere

However, the computed temperatures give us a baseline to indicate what we need to do, or rather what it may be physically possible to do to change that planet’s surface temperature.

Thus for humans, the ideal Martian temperature is much colder than what we would like, and so we must look to implementing a substantial greenhouse effect via an atmosphere.

For Venus (disregarding the actual temperatures at present), we need to increase the albedo (reflectivity) of the planet from the ideal to reduce the surface temperature.

The Earth already has a very slight greenhouse effect through the existence of atmospheric greenhouse gases, and thus its mean surface temperature is just slightly higher than the ideal temperature we have computed above.

The actual mean surface temperatures of Venus, Earth and Mars are given below.

Actual Mean Planetary Termperatures

Venus 740 K (467 C)
Earth 288 K (15 C)
Mars 220 K (-53 C)

Thus we see that both Earth and Mars are reasonably close to their ideal temperatures, with Earth being slightly higher and Mars slightly lower than that predicted for a planet with no atmosphere. We might thus be tempted to conclude that the atmosphere of both these planets has only a second order effect on the surface temperature.

In the case of Venus however, the surface temperature is substantially higher than what our ideal equations predicted, and indeed the very thick Venusian atmosphere has a controlling effect on the surface temperature of this planet. To reduce the temperature of Venus we thus either need to get rid of a substantial fraction of the atmosphere of we need to change its composition.

  1. tallbloke says:

    This page is worth a read too:

    The solar constant for Earth on this page looks high – 1373W/m^2
    This might account for a big proportion of the discrepancy if the solar constant used by the IPCC of around 1366W/m^2 is correct. Maybe Leif can tell us how it is calculated/calibrated.

    The calculation idealises the average orbit of the planet to be circular. Should the fact that it is elliptical make a difference to TSI at the TOA? I can see it might, because Earth moves slower when it is further from the Sun. This means Earth spends a bigger proportion of the year at a distance where the TSI is less than it does where it is more. Can anyone provide a formula to deal with that?

    Google has over 7 million hits for the 3.86×10^26 watts figure for solar output, so we can take that as read I think.

  2. Stephen Wilde says:

    I think my previous guest post is highly relevant here.

    On a water planet greenhouse gases make no difference to the equilibrium temperature, merely the speed of the water cycle which then dictates the surface air distribution (subject to modulation from top down solar effects) so as to achieve a matching thermal equilibrium at the top of the atmosphere.

    The significant point of equilibrium is therefore not TOA (Top Of Atmosphere) but TOO (Top of Ocean) more specifically the point where the cooler 1mm deep surface layer of water is in contact with the ocean bulk below.

  3. Stephen Wilde says:

    Essentially you have to treat the Earth as having two very different atmospheres, one of water and the other of air and the former controls the latter.

  4. tallbloke says:

    Hi Stephen,

    May well be, but none of that affects the basic Stefan Boltzmann equation, so we can try this out for fun and interest. What I’m actually after is the change in the top-down energy inputs caused by orbital changes, so we can plug that into a discussion of the Milankovitch cycles and how they relate to ice ages in the next post. Hence my comment about the difference between a circular orbit and an elliptical one.

    Whether or not eh S-B eq is appropriate is of course another question. 🙂

  5. Stephen Wilde says:

    The SB equation remains valid under my scenario.

    The oceans set the equilibrium then if the surface air temperature starts to diverge then the surface pressure distribution changes to adjust the speed of the water cycle.

    That change in speed keeps the TOA in line with the TOO and satisfies SB.

    The point being that because the thermal properties of ghgs canot affect the ocean their effect on the system equilibrium is negated by a changed rate of energy loss from air to space.

    It is that flexibility of the water cycle that keeps the system in balance with SB obeyed and energy out equalling energy in for the system as a whole at ALL times DESPITE short term albedo variations temporarily altering the amount of solar energy that gets into the oceans.

    Of course a permanent or long term change in solar input to the oceans would affect overall system temperature but in the short term the variability of the water cycle maintains the energy in/energy out balance and satisfies SB.

    So after a while an elliptical orbit could have a noticeable effect but only if it changes the energy content of the oceans for a longer period of time than the longest of any underlying oceanic variations.

    The longest oceanic cycle I know of is the thermohaline circulation at 1000 to 1500 years.

    So, for your calculations to be useful, you would need to separate the orbital effects from internal oceanic effects which I don’t think we can do at present.

    What we really want to know is what would the Earth’s temperature be without oceans. I think you would find that that would account for ALL the so called discrepancy between the blackbody calculation and reality.

    The oceans also suppress the greenhouse effect so until you get rid of the oceans the greenhouse effect has no relevance other than contributing to a tiny change in surface pressure distribution.


  6. tchannon says:

    I have strong views on the subject and usually walk away.

    I’ve only scanned the post, read it later. Looks like a calculation attempt based on Boltzmann.

    The maths most often used can be seen on the wikipedia pages, without actual calculations, hand waving. The talk pages are highly illuminating, including Connolly and cronies, the interest though is how a number of individuals have pointed out a fatal problem with the math and shown how it does not work for elsewhere. Still no movement on position. (I kept silent)

    I’ll leave that one for the moment, will be similar math to the article here.

    A different way of deducing body temperature is from basic physics, no radiation is sight.

    In a simple radiative system body temperature comes from temperature/size of heat source, temperature of cold sink and distances. Most factors cancel out to one.
    Cold is easy, deep space, ~4K
    Hot is more difficult, the surface of the sun but that is not the centre of the sun, circa 5500K, also the sun varies in radius.
    And the rest is inverse square law.
    No figures given.

    That is the ratiometric approach and why I say that a proportionate change applies to all bodies. Change the sun by 1%, all other bodies change by 1%, trivially simple. Note: be very wary of time constants, these are all steady state conditions and tend to very long times indeed.

    I think the massive elephant in the whole thing is emissivity and it’s inverse.
    In my view and for any uniform body this cancels, vanishes from the math, applies to any method.

    Deviation from the normal temperature of the body in a radiative system will occur if the emissivity (albedo, whatever name you want) is different heat side from cold side.

    Also important is the conductivity or other method of heat transference from hot side to cold side: copper sphere is different from plastic. This also gets into what exactly is meant by the temperature of a body, where and how is it measured.
    If we have a sphere shiny one side and matt black the other it can deviate from basic temperature, there is a differential. However, spin the body and it averages.

    At this point lets go back to time constant. The true temperature is for the whole body to it’s core: it is the core temperature which matters. The time constant will depend on the materials, the conductivities. Earth, radioactively heated core (etc.) and an insulative atmosphere, is going to be mighty complex. Venus, goodness knows and temperature of what exactly? The temperature inside a complex system and where?

    Finally, for reasons that I find sinister there is a widespread con-trick played on people, abuse representation of the Boltzmann situation for the solar system.
    The correct way to plot the emission vs. wavelength for a body is log/log, both axis. The usual is long/lin and with a very restricted linear range.

    Plotting the sun and earth at the same time is trivial with log/log but log/lin is not reasonable. Tricks abound, such as using split scales, offsets and very often chopping off most of the data.

    Why? Perhaps there is fear of showing the truth that for a black body the sun emits more at *all* wavelengths, more radiation arrives from the sun at so called ghg emission wavelengths.

    log/log looks like this, sun only.

    There we are no figures, no math. Shuffles along wall. Maybe later when I have read the article properly.

  7. Malaga View says:

    What temperature would Earth’s surface be without greenhouse gases?

    Nobody knows… and nobody will ever know precisely.
    This is because we cannot perform a controlled experiment…
    There is only one earth.
    We cannot remove greenhouse gases to see what happens.

    Therefore, any answer is based up theory, guesses and beliefs systems.

    If you look at the standard theory then we get into the black body calculations… But these calculations are fraught with problems:

    1) The earth is not a black body.
    The albedo of the surface and atmosphere continually vary.

    2) The earth is not a greenhouse because it does not have a glass roof.

    3) The earth is not heated constantly on any timescale.
    Solar input varies from 1373 W/m2 when the sun is overhead
    down to 0 W/m2 during the night and polar winters.

    4) The earth surface is fractal in nature and is not uniform…
    plus the temperature varies with altitude.

    5) The primary greenhouse gas is water vapour and the concentration
    of water vapour in the air is variable… Wiki says: 1% to 4% at the surface

    5) The earth is also a cooling lump of rock in space but
    we have no idea how much energy is released geo-thermally.

    6) The climate system is so complex we cannot quantify how much heat
    is stored and distributed by the deep oceans or atmospheric winds.

    7) The weather system is so complex and variable that we cannot
    even accurately model the energy balance, heat transfers or the weather.

    Therefore, any theoretical calculations are fundamentally flawed..
    any calculations based upon averages are bogus and misleading.

    For example:
    The famous Trenberth energy balance diagram.
    How does this explain what happens at night?
    How does this explain 1373 W/m2 when the sun is overhead?
    How does this explain Hadley cell heat distribution.

    Personally, I am with E.M. Smith when he writes:

    Folk who have been reading here for a while will know I’ve got the general thesis that the lower atmosphere is dominated by convection. That it completely swamps Infrared. You can see this easily in any given day as the clouds form, water from the seas and trees evaporates, rises into the sky, forms clouds, then falls again as rain.

    However, the real kicker is E.M. Smith’s masterpiece: Ignore The Day At Your Peril

    So every day we have tons of air convecting and tons of water evaporating rising, dumping heat, and falling again. We have kilowatt scale impacts from changes of cloud cover. And all of it drops off each night as it finishes it’s job of dumping the 1,300 kW/m^2 of added heat back to space. And in that milieu CO2 counts for nothing. It does nothing.

    Put at it’s most basic: The decision to use a DAILY AVERAGE temperature hides the actual processes involved in dumping heat. Using a MONTHLY AVERAGE simply assures that all the interesting processes are completely hidden and their effects sterilized.

    From the very first step, the creation of a “monthly average temperature” for each place in the temperature data set, the “Climate Science” of “Global Warming” is broken and un-physical. They have their “time scale” all wrong.


    So the weather is dominated by WATER…
    And the green house gas effect counts for nothing.

  8. tallbloke says:

    OK OK, calm down everyone. This post is NOT about trying to deal with the entire co2 driven climate change debate. 🙂

    Let’s ignore changes in co2, and concentrate on the questions posed in the post. Imagine co2 is stable, and we’re interested academics, who want to know how much warmer the planet is with its cozy blanket of water vapour with the iddy biddy bits of co2 decoration along the edges than it would be without it.

  9. Nick Stokes says:

    The calculation is correct as far as it goes. But the Earth currently reflects about 30% of sunlight. This calc assumes that GHGs are removed and the albedo is removed – ie black body. The usual calc keeps it fixed.

    The thought experiment is artificial. If water vapor is to be completely removed, then the oceans would have to go too, which would probably increase the albedo. But also clouds would go. So who knows? But black body is a bit extreme.

  10. tallbloke says:

    Hi Nick, and thanks for that. So really, the co2 effect is less than the IPCC claim? Since most of the GHE is down to water vapour? Got any figures? 🙂 🙂

  11. Stephen Wilde says:

    ” how much warmer the planet is with its cozy blanket of water vapour with the iddy biddy bits of co2 decoration along the edges than it would be without it.”

    Zero because we cannot remove water vapour without removing the oceans and the extra iddy biddy bits of non water vapour GHGs just make the water cycle go faster.

    Otherwise you would have to have a fixed surface pressure distribution with no flexibility in the speed of the water cycle.

    You would then have to observe zero increase in the rate of evapopration when more energy is added to the air but that just doesn’t happen. Warmer air always gives more evaporation. Even warmists accept that but they don’t follow through. Since warmer air also increases the differential with space, condensation speeds up too so the net effect is faster ejection of energy from air to space.

    That is why there is no hot spot at the top of the troposphere. Instead of a hot spot forming the tropopause just rises a bit as part of the faster cycle.The lapse rate is what makes the troposphere rise instead of allowing a hot spot to form.

    Again it is back to atmospheric pressure which determines the lapse rate as well as the energy value of the enthalpy of vaporisation.

    The evidence is all around us.

    Some say that without GHGs no energy would be retained and we would descend into a snowball Earth.

    How could that be so when solar shortwave energy would still be going into the oceans and the oceans would still rise to their OWN equilibrium temperature and once that is achieved we still have a water vapour driven water cycle with or without any other GHGs ?

    Adding additional GHGs other than water vapour just speeds up the water cycle with a miniscule unmeasurable acceleration of that cycle.

    To affect ocean equilibrium temperature the GHGs have to add significantly to atmospheric pressure at the surface but they do not.

    Indeed Miskolczi suggests that in practice more non water vapour GHGs results in less water vapour with the optical depth of the atmosphere unchanged. In other words the water cycle speeds up to accommodate the extra GHGs.

    If it were not so the Earth could never have maintained liquid oceans since they were formed.

  12. Roger Andrews says:


    Could you clear up a point for me? When you talk about the “earth’s surface temperature” are you referring to surface air temperature or sea surface temperature? I ask because the two are about 4C different (mean global SAT is about 15C and mean global SST is about 19C).

  13. tallbloke says:

    OK, so we remove the oceans as well as the non water vapour GHG’s, and pick a suitable emissivity to plug into the S-B equation and we get a figure for the temperature of the Earth with no GHE or HWB effect.

    What would that temperature be?

  14. tallbloke says:

    Roger, lets go with SAT, since we just pumped the oceans into space so we can get on with our experiment.

  15. Doug Proctor says:

    Fellows of the Calculator:

    Without an atmospheree, the Earth’s average temperature is 379K or some such. What would the equator to pole difference be as a result of curvature, and what would the sunlit side vs the dark side?

    The averages are interesting, but the differences from some point to another and from noon to midnight are what we experience. These are most pertinent to our climate (and weather); it would be of great pertinence if we knew that.

    (I know it is a sinusoidal function equator to pole, noon-to-midnight plus T(4) re-radiation to sunrise. Our orbital excentricity is 19 W/m2 Jan to July, also sinusoidal. I just don’t have a clue how to graph it.)

  16. Stephen Wilde says:

    What would that temperature be?

    The Moon ?

    “mean global SAT is about 15C and mean global SST is about 19C.”

    That’s useful to know. I was aware of the difference but not the quantity.

    So any process that causes those two temperatures to diverge OR converge would result in a shift in the surface pressure systems.

    That temperature difference being set by the atmospheric pressure via the enthalpy of vaporisation. If pressure were higher the difference would be lower and vice versa.

  17. tallbloke says:

    Stephen, probably right. So what is the global average temperature of the Moon?

  18. Stephen Wilde says:

    Actually there are differences to the Moon but it wouldn’t be a lot different since Oxygen and Nitrogen don’t have strong thermal responses to solar radiation.

    Also the Earth has more internally generated heat but apparently not a lot.

  19. Anything is possible says:

    There seems to be a relationship, based on our limited knowledge of conditions on other bodies in the Solar System, that, the thicker their atmospheres (regardless of composition), the harder it becomes to explain their temperatures using radiative theory alone.

    The polarisation of the “Greenhouse effect vs. Gravity effect” debate never ceases to amuse me. They are not mutually exclusive, and I believe you need a combination of the two to properly describe temperatures of both the Earth and Venus (My take on this is that the thicker the atmosphere, the more important the “Gravity effect” becomes).

    A related thought experiment :

    Suppose we were to dig a hole in the Earth’s surface large enough to contain all of the atmosphere ( 1000km deep covering 1% of the surface would do the trick) : Adiabatic theory implies that the temperature at the bottom of the hole would be in the order of 10,000C. Sounds crazy, but I think it might just be true.

    What does everyone else think? I’d be really interested to hear all your views on this one.

  20. Malaga View says:

    we just pumped the oceans into space so we can get on with our experiment

    To make this experiment truly scientific should we also:

    1) plug up all the volcanoes, hot [air] geysers and hot [air] springs…
    2) return the earth to the stone age to remove urban heat island and airport heating effects…
    3) block off cosmic rays and ionised particles…
    4) paint the poles (and Greenland and mountain tops) white as we have no water for ice…
    5) fly lots of white kites to emulate clouds in a waterless sky…
    6) zap any meteorites so they can’t heat the atmosphere as they crash to earth…
    7) use electric fans to emulate warm ocean currents…
    8) get everyone to hose down their neighbour with petrol to emulate rainfall…
    9) get everyone to jump up and down to emulate waves and tides…

    Alternatively we can analyse the humour of Mr Wise by removing Mr Morecambe’s lines from the Morecambe and Wise scripts 🙂

  21. eilert says:

    What I do not get why people insist that the black body temperaure schould be calculated at the surface of a planet. The Stephan Boltzman equation only says that a black body will radiate with the forth power of its temperature. It does not say anything about the internal distribution of energy in the system.
    A planet system, which might include an atmosphere, solid surface and a liquid ocean, like Earth, is usually not a black body, but on average does behave like one. Thus the system as a whole and not only part of it, needs to radiate with the black body temperature. That is exactly what is found by observation.
    Thus it is totally wrong to determine the so called greenhouse effect by the difference between the black body temperature and the surface temperature. This difference is due to a number of different factors including thermo dynamic effects (conduction, convection, evaporation), heat sinks (expressed as heat capacity of the various solids, liquids and gasses), pressure differences, radiative processes etc, which determine the internal energy distribution of the planetary system.

  22. Malaga View says:

    REG: Yeah. All right, Stan. Don’t labour the point. And what have they ever given us in return?!

    XERXES: The aqueduct?

    REG: What?

    XERXES: The aqueduct.

    REG: Oh. Yeah, yeah. They did give us that. Uh, that’s true. Yeah.

    COMMANDO #3: And the sanitation.

    LORETTA: Oh, yeah, the sanitation, Reg. Remember what the city used to be like?

    REG: Yeah. All right. I’ll grant you the aqueduct and the sanitation are two things that the Romans have done.

    MATTHIAS: And the roads.

    REG: Well, yeah. Obviously the roads. I mean, the roads go without saying, don’t they? But apart from the sanitation, the aqueduct, and the roads–

    COMMANDO: Irrigation.

    XERXES: Medicine.

    COMMANDOS: Huh? Heh? Huh…

    COMMANDO #2: Education.


    REG: Yeah, yeah. All right. Fair enough.

    COMMANDO #1: And the wine.

    COMMANDOS: Oh, yes. Yeah…

    FRANCIS: Yeah. Yeah, that’s something we’d really miss, Reg, if the Romans left. Huh.

    COMMANDO: Public baths.

    LORETTA: And it’s safe to walk in the streets at night now, Reg.

    FRANCIS: Yeah, they certainly know how to keep order. Let’s face it. They’re the only ones who could in a place like this.

    COMMANDOS: Hehh, heh. Heh heh heh heh heh heh heh.

    REG: All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?


    REG: All right, but apart from the rain, the rivers, oceans, seas, clouds, weather, agriculture, fishing, and washing, what has CONVECTION ever done for us?

  23. tallbloke says:

    Lol, nice one Tim.

  24. T G Watkins says:

    Lubos Motl did an analysis of the Venusian atmosphere replacing the CO2 with a diatomic gas, nitrogen I think. There was only a relatively small fall in surface temp., his conclusion being that the high surface temp is due to its orbit and adiabatic effect of atmosphere rather than its composition.

  25. tallbloke says:

    TGW: Thanks for that. If you find a link, drop it in.

  26. Stephen Wilde says:

    Some sensible posts here.

    So we have two basic effects:

    i) Density which links to gravity to produce pressure and heat at the surface.

    ii) Composition whereby certain types of molecule add or subtract from the density effects by virtue of their individual thermal characteristics.

    As pointed out by ‘Anything is possible’ the outturn in any given planetary scenario is a combination of both.

    But then we have another aspect in terms of the layering of the atmosphere.

    I would contend that our oceans are just an extra layer of atmosphere but they behave very differently from the air above. Thus the physical properties of water become highly significant due to the huge energy exchanges involved in changes of state.

    The same would apply to any planet with a gas above a liquid, it doesn’t have to be water.

    Then the gas above the liquid can be layered too and respond differently to solar input at different levels. The Earth’s atmosphere seems to do just that with opposite signed solar responses above and below 45 km (approximately at the stratopause) as per the comments of Joanna Haigh.

    So with that degree of complexity what is it that arranges compliance with basic physica rules such as the SB equation and,( at equilibrium ) for energy in to match energy out ?

    Well the obvious answer is movements within the fluid components of the system whether gases or liquids sometimes offsetting and sometimes supplementing one another and so it is.

    And in the gaseous portion phase changes at varying levels to accelerate or decelerate upward energy transport as necessary to keep the system in overall equilibrium.

    Quelle surprise !!

    Scrap ALL the models and start again from those principles.

  27. P.G. Sharrow says:

    And soon the operations of the sun will also be plain. 😉 pg

  28. Two questions: 1)What is it the microwave length wave that heats up water? 2)What is it the wavelenght of a microwave oven?

  29. Nick Stokes says:

    tallbloke says: June 6, 2011 at 1:42 pm
    No, no figures. The difficulty is well known – it just isn’t additive. Remove CO2 and you still have a big GHE from water – not so much difference. But remove water – you still have a substantial GHE from CO2.

    What is clear is that adding CO2 increases retained heat. Which is what matters.

  30. tallbloke says:

    Hi Nick,
    you’re a fair bloke, and I don’t have figures either, so I was just joshing with you. I do wonder why Mars is cooler with its co2 atmosphere than without according to the calcs above though. Is that due to convection?

  31. Nick Stokes says:

    No, same deal. The calc shows that Mars would be warmer without its atmosphere and without albedo (ie black). The albedo cools more than the thin atmosphere warms.

  32. A matter of thinking it again from the start- as we have preconceptions on everything-:

    Temperature is a consequence not a cause, thus IR emission it is a secondary effect. What matters, then, are the reactants not the products of the reaction.
    Do we know, for sure, which part of the spectrum of radiations our earth receives accounts for the secondary production of IR radiation which we call “heat”?

    How is it so, as M.Vukcevic has shown, that NH temperatures correlate so well with changes in GMF? http://www.vukcevic.talktalk.net/

    Or….perhaps, it is more “cool” ,”nice” and “progressive” to relate temperatures with those pesky fossil fuels produced by too big and ugly capitalistic companies?

  33. Of historical interest, the Handbook of Climatology pub in 1903 references a calculation of the mean Earth temp without an atmosphere as 46 degrees (I assume in F or 7.8C) using SB.

    see pg 102:


    leaving only 7.2C to be accounted for by a “GHE,” or just the adiabatic lapse rate

  34. Zeke the Sneak says:

    It’s a step in the right direction to compare weather patterns/climate of the various planets in the solar system.

    However, the downside is that the discussion slouches so myopically into temperature (as Adolfo posted), and mean temp at that. I find this unhelpful and a sleight of hand, because the weather on the other planets include constant lighting storms, 1200 mph winds, twisters the size of mountains, auroras the size of earth, and clouds called “skooters” which travel in excess of 1000mph. There is clearly an electrical power input into the planetary weather systems.

    Now what is the meaning of mean temperature? What is the mean temp of the Sahara Desert? With a CO2 level of 0 – 160 ppm, all of the vegetation would die and the land would become a desert, answering our question, I think, about the temp of the earth without it. It would be in the hundreds during the day and freezing at night, and what rain clouds did manage to give rain upon the land would be few and the rain would be evaporated before it hit the ground.

  35. Tim Channon says:

    The reference to 272 degrees (0K) says it is C

  36. coldlynx says:

    There is a series of basic error in common heatbalance calculations.
    Basic calculation use solar constant of h – 1370W/m^2 at TOA and 1000W/m^2 at surface.
    With the wrong interpretation that only the difference is absorbed by the atmosphere.
    That is the first mistake. The radiation at surface are from sun direct and from the atmosphere itself.
    Direct shortwave and atmosphere longwave combined result in about 1000W/m^2 a sunny day.
    Yes that is the backradiation….
    That mean the surface is even less heated by direct solar radiation than even in the simple models.
    And here is basic mistake two. The radiative heat balance between system earth and space is not located at surface level. Cant be since the atmosphere do absorb and emit heat. And atmosphere are mainly heated by convection.
    The radiative balance point between system earth and space must be in the atmosphere.
    Then is the GHG question a matter on which altitude to calculate with.
    Below the balance altitude is the atmosphere mainly heated by convection, not radiation. Above system earth heatbalance altitude is system earth cooled mainly by radiation.
    IPCC 33 degrees K would then be indicating a radiation balance level of approx 5500 m or about 18000 ft.
    Such a coincidence that 50% of the atmosphere by mass is below an altitude of 5.6 km (18,000 ft).

  37. Zeke the Sneak says:

    Right, water is THE greenhouse gas, so no water allowed in this hypothetical. Sorry-orry. I will archive this post to make up for that.

    tallbloke says:
    June 9, 2011 at 12:06 am
    Solar: We have sunspot records since 1749, and they indicate the sun got more active in the C20th. However, there is a strong move from the mainstream to say the Sun hasn’t varied enough to be the cause of warming in the C20th. At the same time they have to invoke the sun to explain climate change before co2 took over so they are in a contradiction, and don’t like to discuss it. The only solar measure they will use is TSI, which doesn’t vary much (0.1% – enough to cause a ~0.07-0.15C change in surface temp over the 11 year solar cycle, without considering amplification caused by changes in humidity, cloud cover etc). They won’t consider the fact that various wavelengths within the TSI (total solar irradiance) vary a lot more, especially UV. UV variation has poorly known but large effects on ozone, plankton density and etc which have poorly understood but possibly large effects on the absorbance of energy into the ocean, cloud cover, and etc.

    Clouds: The elephant in the room. Simple calcs show that a 1% variation in tropical cloud cover could reverse or double the warming trend. We can’t measure cloud cover (and droplet size, density etc) accurately enough, so the models assume it remains constant. The empirical data (not without its problems) says cloud cover dropped in the tropics 1979-1998. Empirical study of the satellite data shows overall cloud feedback is negative. The modelers assume it is positive.

    Sea surface temp: There’s a pretty flat trend in the southern hemisphere. Co2 mixes fairly quickly from where it is emitted worldwide. How is it that global warming supposedly caused by co2 has warmed the northern hemisphere more than the south? The answer would seem to be that back radiation from greenhouse gases warm the land but not the ocean so much. Since the global ocean surface temp drives atmospheric temp, they don’t really want to go there.

    The fixation with global average surface air temperature masks the underlying important variables:
    Ocean heat content, which is only known with reasonable accuracy since 2004, and has been falling, according to people I trust who have managed to get the data.
    Outgoing longwave radiation: The error in measurement is three times the claimed co2 signal.

    There is a lot that those who call us deniers are in denial of. Especially true levels of uncertainty.

  38. Venus: No Greenhouse Effect

    CO2 concentration doesn’t enter in. Albedo doesn’t enter in (this is what the incompetent consensus refuses to see, that you can’t use the S-B equation except on the whole planet+atmosphere system). So the effective, or equivalent blackbody, temperature of the Earth system IS 279K, not 255K as so many think is fact. The Venus/Earth comparison I have done is the definitive evidence, and should be front page news worldwide. There is NO greenhouse effect as promulgated in climate science and planetary atmospheres physics.

  39. tallbloke says:

    Harry, I think your Venus argument is an interesting one. Would you like me to repost it here to help give it wider exposure to constructive criticism?

  40. malagaview says:

    TB: Would you like me to repost it here to help give it wider exposure to constructive criticism?

    And the comments please…

    Second, it is important for readers to understand that we know Venus receives, on average, 1.9 times the power per unit area that Earth receives, simply from their relative distances from the Sun, as my article discussed.

    What is truly remarkable is, a good portion of that power is reflected back into space by Venus’s thick cloud cover (which makes the planet particularly bright to Earth observers), yet the Venus atmosphere is still heated by 1.9 times the power that heats the Earth atmosphere, as the temperature data shows. Thus we know that the visible portion of the Sun’s radiation is not what heats the two atmospheres (because Venus doesn’t take in 1.9 times as much visible light as the Earth, it takes in substantially less).

    Both atmospheres do, however, absorb infrared, and the comparison I have made shows they both must absorb the same portion of the incident infrared from the Sun, thus preserving the 1.9 power ratio calculated from their distances from the Sun.

    Furthermore, they must absorb this portion directly, not after absorption and emission from the surface, since the surfaces of Earth and Venus are likewise very different (deep ocean vs. solid crust) and would take up different fractions of the infrared, which again would spoil the 1.9 power ratio that is in fact indicated by the Venus/Earth temperature comparison. That the atmospheres must both be warmed by direct absorption of incident infrared radiation, rather than by prior warming of the planetary surface, is directly counter to common scientific belief, and is just as important as the primary finding that there is no greenhouse effect observed on either Earth or Venus.

    Because I particularly like this punch line:

    This underscores how badly “consensus” science has erred in understanding the thermodynamics of planetary atmospheres.