lördagen den 3:e mars 2012

Can The "Greenhouse Effect" Be Detected?


The recent exhange with Roy Spencer and Fred Singer concerning the "greenhouse effect" and "backradiation" identifies three groups in the climate debate with the following standpoints:
  1. Alarmists: There is a greenhouse effect and it threatens to overheat the globe.
  2. Skeptics: There is a greenhouse effect, but it is so small that it cannot be detected.
  3. Deniers: As long as no greenhouse effect has been identified, one can act as if there is no greenhouse effect.
Roy and Fred belong to 2. and myself to 3. The discussion gets complicated by the fact that "the greenhouse effect" is not clearly described in the literature, but it is somehow connected to the radiative properties of the atmosphere:

Both alarmists and skeptics assume as a starting point that doubled CO2 will cause global warming by 1 C, which is referred to as no-feedback climate sensitivity. Alarmists then inflate it to 3 C with positive feedback and skeptics to about 0.5 C with negative feedback.

Both alarmists and skeptics thus firmly believe that science says that increasing the absorptivity of the atmosphere a little by doubling CO2, will cause warming.

Deniers are not so sure about that referring to the following argument:
  • Earth surface temperature is determined by the lapse rate.
  • Lapse rate is determined by thermodynamics with radiative forcing.
  • Fully transparent atmosphere may be isothermal with zero lapse rate.
  • Fully opaque atmosphere may be isothermal with zero lapse rate.
  • Reality is somewhere in between with a certain lapse rate.
  • It is not clear if more CO2 will increase or decrease the lapse rate.
  • It is thus not clear if more CO2 will cause warming or cooling.
  • There is no convincing evidence that any effect of doubled CO2 can be detected.
The dividing line goes between alarmists on one hand and skeptics/deniers on the other hand.

The quarrel between skeptics and deniers, about the existence of an effect which cannot be detected, seems to be of minor scientific importance compared to the main question of significant global warming or not.

14 kommentarer:

  1. A transparent atmosphere, for example, 100% N2, is isothermal and static. You have Tt (TOA temp) = Ts (surface temp) = Tef (effective temp).

    Adding 300 ppm of CO2, as for Earth, the troposphere still remains transparent except that for the CO2 bandwidth at 15 micron, which becomes completely opaque below the TOA, whereas it returns transparent at the TOA. The radiative balance becomes
    xTt^4 + (1-x)Ts^4 = Teff^4
    where x is the % of CO2 band emission respect to total spectral emission that can be statistically measured by satellites.

    Notice that because of the cooling TOA the troposphere becomes adiabatically convective and then Tt/Ts = (Pt/Ps)^(R/Cp). Assuming x = 0.04, you obtain Ts = 1.01Teff, Tt = 0.63Teff and a mean temp about 0.82Teff. That’s, the CO2 causes a tiny worming at the surface and a strong global cooling. In other words, if Earth had a dry atmosphere it would be unlivable as the GH effect of the sole CO2 is negligible.

    Michele

    SvaraRadera
  2. I despair for physics, with such "teachings". The lapse rate is not dependent upon a particular mode of energy input (such as convection). The atmospheres of Earth and Venus are not transparent, rather both directly absorb about 20%--both of them, the SAME PORTION--of the total incident solar radiation, and are fundamentally warmed in that way--NOT from the planetary surface (heat from the surface is thus only involved in the WEATHER, not the fundamental warming of the atmosphere). When Michele and Claes speak about an isothermal atmosphere, they obviously do not know what they are talking about, because as long as there IS a gaseous atmosphere (enough energy/molecule--and therefore temperature--to BE A GAS), the temperature lapse rate structure MUST form as the equilibrium distribution of the available energy. To have an isothermal atmosphere, you would have to have an isobaric (same pressure) atmosphere, but the atmosphere is NOT WEIGHTLESS, so the pressure increases with depth, and in reality you get the hydrostatic condition and the hydrostatic temperature-lapse-rate structure of the well-known Standard Atmosphere. Forget "adiabatic" and "convection", that is unreal, falsely constraining, dogma, from those who have been deluded into believing the planetary surface warms the atmosphere. Remember instead, direct absorption of solar IR, and "hydrostatic equilibrium". You are incompetent--if you are a physical scientist--to think otherwise. My Venus/Earth temperatures comparison demonstrates the simple, definitive facts I have just given, for those two, detailed planetary atmospheres. The entrenched incompetence in climate physics is not a minor problem, it is an unsupportable abomination.

    SvaraRadera
  3. The argument with an isothermal atmosphere was only made to indicate that it is not sure that
    more CO2 would cause (small) warming, that it could as well cause (small) cooling.

    SvaraRadera
  4. Thanks for sharing the information.I am doing a research and your article will surely help me a lot.Thanks

    SvaraRadera
  5. The isothermal atmosphere is a very effective starting hypothesis if you want to understand the physics of the heat transfer from the surface to outer space. I’m considering only the vertical gradient without the horizontal ones, then the weather has nothing to do.
    Convection isn’t a “particular mode of energy input”, it is simply the particular mode of heat transfer put in place by mass transfer which requires the minimum temp gradient for a large heat flux. It makes sense to exist if somewhere, above, the heat carried up can be radiated to space.
    The lapse rate shows the existence of the heat transfer between surface and TOA, then, the surface supplies heat to radiating TOA: no radiating TOA no lapse rate.

    Michele

    SvaraRadera
  6. Yes, a possible trivial stationary state of a fully transparent or fully opaque atmosphere is isothermal with no weather and no climate. Only of interest in a discussion about the effect of a bit more CO2: warming or cooling or nothing?

    SvaraRadera
  7. The Venus, Earth and Mars spectra, when compared between each other, show that the width of the CO2 15 micron band is very similar despite the CO2 of Mars is 25 times the terrestrial and that of Venus is 300000 times. It seems that a bit more CO2 should not cause anything quantifiable.

    It is interesting the fact that adding few ppm of CO2 to initial transparent atmosphere you obtain a strong global cooling and only a slight warming of the surface.

    The sole CO2 doesn’t cause a significant gh effect, as evidenced by Mars that despite its high content of atmospheric CO2 has not at all gh effect.

    Michele

    SvaraRadera
  8. Michele, interesting that you mention mass transfer. When the Schmidt number (Sc= viscosity/(density*diffusivity)) was mentioned in comments on a post on another blog, Gavin Schmidt (of NASA GISS & Real Climate) obviously had to refer to Wiki but could not figure out its relation to mass, heat and momentum transfer. But then so-called climate scientists and physicist do not appreciate measurement, real experimentation and empirical relationships. Not sure where Harry D H fits in with his criticism of Nikolov & Zeller's interesting empirical relations see here http://tallbloke.wordpress.com/2012/02/16/unified-theory-of-climate-objections-and-replies-so-far/
    cementafriend
    (my wordpress profile does not work here)

    SvaraRadera
  9. Cementafriend,

    some time ago, I argued with Kevan Hashemi at

    http://homeclimateanalysis.blogspot.com/2011/03/surface-cooling-part-vi.html

    and many other his post of the blog, that the atmosphere thermal behavior was almost completely explained by fluid dynamics assuming the presence of radiating layers at the two sinks of the Earth’s atmosphere: tropopause and mesopause.

    The conclusion on that topic are also in my comment on SkS

    http://skepticalscience.com/news.php?p=1&t=54&&n=803#56489

    I would like to know your opinion.

    Michele

    SvaraRadera
  10. For those who visit this site open to new, definitive facts: The lapse rate, as a basic concept, does NOT require the surface heating the troposphere. The latter is just a naive assumption and, as my Venus/Earth temperatures comparison has revealed, such surface heating exists only as weather, overlaid on the fundamental equilibrium state described by the Standard Atmosphere (which climate science incompetently turned its back on over 40 years ago). That comparison clearly and simply shows that the troposphere is fundamentally warmed only by direct absorption of solar IR radiation; there is no other physical explanation (given the great differences in the CO2, albedo and planetary surfaces of Venus and Earth) for my factual finding that the observed Venus/Earth atmospheric temperature ratio, over the range of Earth tropospheric pressures, is due only to the ratio of the two planets' distances from the Sun. From that finding (completely unexpected by defenders of consensus climate theory, although it should have been discovered 20 years ago), logic dictates that both atmospheres MUST be warmed by the SAME portion of the incident solar, diluted in each case only by the planet's distance from the Sun; and furthermore, this can only be through direct absorption of that portion of the incident solar, not by heat from the surface. Like it or not, this is elementary and inescapable reasoning, and a definitive, fundamental correction to the common belief of scientists--and insisted upon here, dogmatically and without factual support, by Michele, and unquestioningly accepted by Claes Johnson--that the surface warms the atmosphere; the latter has simply been disproved by my Venus/Earth comparison. So vertical heat transfer from the surface does not fundamentally warm the troposphere; that which does not simply follow the lapse rate up through the atmosphere, without heating it, and on out to space, must only manifest locally and/or transiently, as weather (including the observed variations in the general circulation of the atmosphere). All of the posturing by the miseducated and thoroughly deluded scientists of today will not keep my Venus/Earth findings from forcing the fundamental rethinking of climate science, and the rethroning of the stable Standard Atmosphere. It is just a matter of time.

    SvaraRadera
  11. Michele, I had a quick look at your second reference. I saw that the blog is hosted by Chris Colose who is reported as a postgraduate student with no understanding of physics (or has been badly educated) and from his comments, which I have seen on Climate Etc, has no experience or knowledge of heat transfer. That put me off from reading further.
    I will look at your first reference when I get some time
    cementafriend

    SvaraRadera
  12. Michele, I had a quick look at your first reference. A positive for Kevan Hashemi is that he has some engineering qualifications (which should normally give him a wider perspective on technology), a good knowledge of mathematics & some experience in modelling. Negatives however include: no qualifications in chemical or mechanical engineering which could lead him to understand heat transfer, no evident experience with heat transfer processes, an acceptance of the false concepts thermodynamics expounded by so-called climate scientists.
    From my quick look it appears that Kevan only recently realised that evaporation and condensation of H2O play an important part in the atmosphere. By having no background in chemistry (or chemical engineering) the climate scientists and their followers ignore the formation of ozone and its absorption of UV. They do not understand the mass transfer at the water surfaces (which make-up about 70% of the earths surface. They not not understand particle mechanics etc.
    Climate assessment is very complex. As I see elsewhere (may have been WUWT) there has been no progress in understanding in the last 30 years inspite of 100's billions dollars of climate "research" and a huge progress in the development of computing and measuring techniques.
    cementafriend

    SvaraRadera
  13. Cementafriend, you have been very polite, thanks very much.
    Michele

    SvaraRadera
  14. "Yes, a possible trivial stationary state of a fully transparent or fully opaque atmosphere is isothermal with no weather and no climate."

    No, adiabatic gradient is per definition independent from any form of energy exchange,
    but dependent of gravity and mass of the atmosphere.
    So it cannot be isothermal.
    If you want to switch off the gravity too, you will not have an atmosphere any more
    Paul

    SvaraRadera