The greenhouse effect is real. If there were no greenhouse gases in the atmosphere, earth would be a cold place. Compare Mars versus Venus – Mars has minimal greenhouse gas molecules in its’ atmosphere due to low atmospheric pressure, and is cold. By contrast, Venus has a lot of greenhouse gas molecules in its’ atmosphere, and is very hot. Temperature increases as greenhouse gas concentration increases. These are undisputed facts.
outgoing radiation = incoming radiation – changes in oceanic heat content
The image below from AER Research explains the radiative balance.
http://www.aer.com/scienceResearch/rc/rc.html
About 30% of the incoming shortwave radiation (SW) is reflected by clouds and from the earth’s surface. 20% is absorbed by clouds and re-emitted back into space as longwave (LW) radiation. The other 50% reaches the earth’s surface and warms us. All of that 50% eventually makes it back out into space as LW radiation, through intermediate processes of convection, conduction or radiation. As greenhouse gas concentration increases, the total number of collisions with GHG molecules increases. This makes it more difficult for LW radiation to escape. In order to maintain equilibrium, the temperature has to increase. Higher temperatures mean higher energies, which in turn increase the frequency of emission events. Thus the incoming/outgoing balance is maintained.
Click for larger image
http://www.aer.com/scienceResearch/rc/m-proj/lbl_clrt_mls.html
The important greenhouse gases are: H2O, CO2, O3, N2O, CO and CH4. The reason why the desert can get very cold at night is because of a lack of water vapor. The same is true for Antarctica. The extreme cold in Antarctica is due to high albedo and a lack of water vapor and clouds in the atmosphere, which results in almost all of the incoming radiation returning immediately to space.
An earth with no CO2 would be very cold. The first few tens of PPM produce a strong warming effect, and increases after that are incremental. It is widely agreed that a doubling of CO2 will increase atmospheric temperatures by about 1.2C, before feedbacks. So the debate is not about the greenhouse effect, it is about the feedbacks.
Suppose that the amount of reflected SW from clouds increases from 20% to 21%? That would cause a significant cooling effect. Thus the ability of GCM models to model future temperatures is largely dependent on the ability to model future clouds. Cloud modeling is acknowledged to be currently one of the weakest links in the GCMs. Given the sensitivity to clouds, it is perhaps surprising that some high profile climate scientists are willing to claim that 6C+ temperature rises are established science.
So the bottom line is that the greenhouse effect is real. Increasing CO2 will increase temperatures. If you want to make a knowledgeable argument, learn about the feedbacks. That is where the disagreement lies.
foinavon:
“Now we know that this interpretation was incorrect. We can measure the water content of the troposphere (upper and all) and determine that in the real world the upper troposphere is moistening (as models predict in fact)[*****]. So we reject Lindzen’s failed hypothesis in this particular respect, since it is shown not to be correct. There’s no problem with that. It’s part of science. However what we shouldn’t do is to retain analyses that we know to be incorrect because we happen to like their implications.”
Oh, yeah? http://www.drroyspencer.com/
And why is it not warming?
John Galt (08:08:54) :
I’ll also repeat my assertion that the GC Models forecast global warming because that’s what they are programmed to do.
just like the computers producing the accurate astronomical ephemeris used for navigation on Earth and in Space, they just do what they are programmed to do.
“An earth with no CO2 would be very cold. The first few tens of PPM produce a strong warming effect, and increases after that are incremental.”
I need help understanding this.
10 ppm = 1 part per 100,000 = one molecule of CO2 in every 100,000 molecules of atmosphere.
1 degree Celsius = a change of about 1 per 300, given that absolute zero in about -272 degrees. This ratio is 3,333 times greater than above.
Therefore how is it that just one molecule of CO2, when added to 100,000 molecules of an atmosphere containing various other gases, will have the power to raise the temperate by a factor of 3,000?
I suspect I am violating a few thermodynamic laws in my questioning, but if someone could explain this in a common sense fashion, then perhaps I would be less of a doubter.
Joel
Thank you. I’m certain that there’s some good science in all of this and the truth will out someday but many of the papers I’ve read seem to base their case on an inadequately proven assumption and just let that assumption lead them to a conclusion. More often than not, the poor quality data doesn’t support either the assumption or the conclusion. Yet this ragtag bunch of reasonable estimates is often misrepresented as being “overwhelming evidence” based on observations. In fact though, the majority is of these papers are chock full of caveats. And when the data doesn’t fit the theory then sometimes an accommodation is made by adding some unknowable factor which is then also estimated – aerosols for example. Or sometimes the data is processed by a statistical filter which gives the desired correlation. Yes I well know this is how science advances but does this conglomeration of unproven, faltering science really constitute sufficiently adequate knowledge to make one 90% certain of anything?
I’ve heard the argument before about a lower actual CO2 effect giving a higher CO2 sensitivity and I took the trouble of asking Wm Connelley how this seemingly perverse notion was arrived at. He produced a simple equation based on an electric circuit feedback view of the world’s climate. I argued that if the climate was actually slightly more complex (as indeed several independent peer-reviewed papers listed on one of Roy Spencers presentations had argued) then this claim of higher sensitivity for a lower CO2 effect was then wrong. He didn’t respond. Again it’s about the assumptions leading the conclusions. If you can’t think of another amplifier then let’s say it’s CO2. I find it to be a pretty lame argument.
Fools rush in where angels fear to tread.
My last message suggested that the 20C maximum temp of the surface of Mars would have 0C as the base line. Therefore CO2 adding 5 or 10 deg C would be an increase of 25 to 50 percent.
This is wrong as the notional base temp would be 0 Kelvin and the max surface temp 293 K. Therefore if +10 deg C was the total added to the surface temp it would be closer to 3.5%.
CO2 and other “GHGs” don’t produce warming; they prevent cooling, which is a very good thing.
Joel Shore (17:20:42) :
“Well, I count a few things. First of all, your numbers are confused. The fractional amount of CO2 in atmosphere by volume is ~0.000385, which is 0.0385%. Since it was ~0.0280% in pre-industrial times, we have raised the level by ~0.010%.”
Before getting to the radiative capacities of CO2 – can you explain what part of the chart created from IPCC data I’ve misinterpreted? The data clearly show that “Global annual man-made CO2 emissions” are .00053% by mass, or .000348% by volume.
Of course Beck and Slocum both dispute your claim that pre-industrial was ~0.0280%. Beck averaging 90,000 accurate chemical analyses of CO2 levels in the air recorded from 1812 through 1961, shows a peak of .0440% in 1820-1825, long before industry made its contribution, and another .0440% peak in 1945.
My calculation of radiative energy man-made CO2 (.000348) will absorb and radiate (in either direction) should coincide with observed global temperature rise – .000348 * .08 (percentage IR that CO2 absorbs) or 0.00002785. My understanding is that thermodynamics of a number this small has no statistical or measurable effect on global climate.
“I need help understanding this.”
Actually, we all do. The original model for this problem using the Stefan-Boltzmann constant comes from Arrhenius, a chemist of note at the end of the 19th century.
His calculations put the temperature of the earth without GHGs, particularly CO2, at 255 degrees C, where the real average temp was thought 283 degrees for a 30 degree difference. The result seemed to fit reality.
His model however did not include the oceans, and his calculations included 30% of TSI reflected back into space. Beyond 7th grade Science the model is worthless. We don’t really have a good model to date.
AJ Abrams says:
Having a certain pressure does not get you around having to obey radiative balance. That is, you have a certain amount of energy coming from the sun to the planet and a certain amount escaping from the planet into space and (barring there being some extreme source of heat in the planet itself) the two have to balance. The amount escaping from the planet into space is determined by the Stefan-Boltzmann Law, i.e., that the power radiated is proportional to the 4th power of the temperature If the temperature of the planet’s surface is higher than what that Law implies it must be to maintain radiative equilibrium, that must mean that the effective location from which the emission into space is occuring is not the surface but rather some other altitude where the temperature is cool enough that the radiative equilibrium holds. This in turn requires that the atmosphere must be IR-active, i.e., that it must be absorbing and re-emitting electromagnetic radiation, that is, essentially that there must be a greenhouse effect.
I’m a science writer and a fan of science. I’ve read all the posts to this point and I’d like to say I appreciate the conversation immensely.
I’d also like to say, to anyone wandering through the mix, to search for a post by ‘cal’ which very clearly states the issue in a basic fashion.
Oh, and thanks for all the material, I have bills to pay.
Bill
gary gulrud (09:08:28) :
His model however did not include the oceans, and his calculations included 30% of TSI reflected back into space.
This is an enduring myth. The 255K comes about this way:
He equates incoming and outgoing energy. Incoming energy at the surface [incl. the oceans] is Fi = S/4 (1 – A) where S is TSI [1361 W/m2] and A is the albedo [=0.3]. For an average blackbody outgoing energy is Fo = aT^4. Equating Fi and Fo gives for temperature T: T=((1-A)S/(4a))^(1/4). Inserting values, gives T = 255K.
Substandard… That’s the description on Steve’s article. The article is full of assumptions which don’t draw a parallel with reality. For example, experimental results show that increases of the mass of CO2 in the atmosphere lead to decreases of ΔT. The algorithm is not complicated and it is intelligible:
ΔT = Δq / m (Cp)
If we increase mass, without increasing q, i.e. incident Solar Irradiance on the Earth’s surface, delta T would be lower. For example, if the concentration of atmospheric CO2 increases x2, the change of temperature would be:
ΔT = 0.0786 J / (0.00138 Kg) (841 J/Kg K) = 0.07 K
If we apply the modified Arrhenius’ Equation, the preferred algorithm of IPCC, the things don’t run better:
ΔT = α (ln 2) / 4 (σ) (K3)
ΔT = 0.423 (W/m2) (0.7) / 4 (5.6697 x 10-8 W/m2 K4) (300.15 K3) = 0.3 W/m2 / 6.132 W/m2 K = 0.05 K
These calculations clearly show that the assumption on that higher changes of temperature obey to higher concentrations of atmospheric CO2 is absolutely false. I didn’t include L and m in Arrhenius’ equation because I opted to compare my equation with the equation from AGW proponents. The difference is that I have used real data, parameters and constants.
Trust me, the physics on which AGW proponents base their “greenhouse” effect is odd; I would say it is out of this world and this Universe… 🙂
Correction: ΔT = 0.423 (W/m2) (0.7) / 4 (5.6697 x 10-8 W/m2 K4) (300.15 K)3 = 0.3 W/m2 / 6.132 W/m2 K = 0.05 K
Concerning the downwards LW radiation and its interaction with surface. There are apparently 5 possible mechanisms:
1/ One mechanism is for the activated molecule to collide with another molecule, and to drop back into a lower energy state; the energy thus freed becomes kinetic energy of the molecules and corresponds to warming the gas. This is absorption. The photon is permanently lost or attenuated from the radiation field.
This is not the case as surface is warmer than atmosphere.
2/A second mechanism for release of the energy increase is the spontaneous transition of the molecule [in the surface] (in about one nanosecond) into its original state by emitting a photon which is identical to the absorbed one except for its direction of propagation. This is scattering, where the photon remains part of the radiation field but the direct beam is attenuated.
This means the LW photon is absorbed and instantaneously re-emitted upwards. Clearly possible. The atmosphere is transparent to this LW radiation.
3/A third mechanism is the activated molecule releases its energy spontaneously but in two stages. Two photons with different lower energies result; the sum of the energies of the two photons equals the energy of the absorbed photon. The direct beam is attenuated; the original photon has been replaced by two photons at longer wavelengths and is no longer part of the radiation field. This is Raman-scattering.
Don’t know if this occurs, but seems identical to 2/. The 2 re-emitted photons are LW radiation and again atmosphere is transparent.
4/Other mechanisms for energy release are fluorescence and phosphorescence. These occur when the energy is not released spontaneously, but after relaxation times of nanoseconds to hours.
Is it possible? Additional informations needed.
5/Another basic type of interaction involves the conversion of molecular kinetic energy (thermal energy) into electromagnetic energy (photons). This occurs when molecules are activated by collisions with each other and the activation energy is emitted as photons. This is emission.
This is the mechanism of radiation emission by surface after solar irradiation. It is not possible to occur for the downwards LW photon as it has first to be absorbed by surface and 1/ prevents this absorption.
It seems that the only possible mechanism of interaction of the downwards LW photon with surface is the instantaneous re-emission of an identical LW photon. The atmosphere is transparent for this LW photon meaning that it escapes directly in space.
Feel free to add information or correct.
Bye,
TMTisFree
Joel,
“If the temperature of the planet’s surface is higher than what that Law implies”
You skipped my question. I know that the greenhouse theory is about time lag for escaping energy, that wasn’t my question.
I asked this in essence: What is the expected temperature of earth given it’s 14.7 psi at sea level? Your comment about altitude temperature is a bit of a red herring here because in atmosphere there are other mechanisms to explain that easily.
However….if, as I have read that the earths, venus’, mars and even jupiter’s temperatures at 1 atm are within expectation given the pressure it would mean that pressure is the regulator. You could have some variance due to other mechanisms like TSI, latent ocean heat + circulations etc just as we see on earth, but there would a cap of the lower and upper boundaries of those boundaries because of PV = nRT . To get above or below expected temperatures you’d have to add or reduce drastically the mount of gas on earth which isn’t going to happen internally. It would have to be from the sun via a large change in solar output or from a collision with a forgein body that either added matter, or blew off atmosphere.
Since that isn’t likely, you are constrained from any sort of run away temperature change on earth.
People often give Venus as some example of “run away” greenhouse, but as I see it Venus suffered from run away increase in pressure. The overall temperate from what I’ve read over the last few days seems to be almost completely explained by it’s pressure at surface, and internal heating from a thin crust as well as some other minor influences. The “greenhouse” effect might be an influence, but not, by far, a dominant one.
And before someone says it was the CO2 increase that increased temperatures that in return increased pressure, I highly doubt that. For one Venus never had a fast rotation given it didn’t have a giant collision with a planet sized object like earth did -i.e the moon. Given it’s slow rotation added to it’s closer proximity to the sun, it was only a matter of time before H2O disappeared. Once that happened CO2 pressures would go up (because it would have no sink). Once CO2 started gathering in numbers the pressure went up creating more heat which caused more CO2 to gas out.
Poor Mercury never had the size or magnetic shielding to gather an atmosphere.
This scenario isn’t possible here on earth for numerous reason (rotational speed being one of them and total TSI being another) until our sun starts to grow some and seeing that is out of human control, I think I’m ok.
Am I missing something here people not named Joel?
Arg, missed the end of tag. It would be cool to have a preview on this blog.
Concerning the downwards LW photon and its interaction with surface. There are apparently 5 possible mechanisms:
1/ One mechanism is for the activated molecule to collide with another molecule, and to drop back into a lower energy state; the energy thus freed becomes kinetic energy of the molecules and corresponds to warming the gas. This is absorption. The photon is permanently lost or attenuated from the radiation field.
This is not the case as surface is warmer than atmosphere.
2/A second mechanism for release of the energy increase is the spontaneous transition of the molecule [in the surface] (in about one nanosecond) into its original state by emitting a photon which is identical to the absorbed one except for its direction of propagation. This is scattering, where the photon remains part of the radiation field but the direct beam is attenuated.
This means the LW photon is absorbed and instantaneously re-emitted upwards. Clearly possible. The atmosphere is transparent to this LW radiation.
3/A third mechanism is the activated molecule releases its energy spontaneously but in two stages. Two photons with different lower energies result; the sum of the energies of the two photons equals the energy of the absorbed photon. The direct beam is attenuated; the original photon has been replaced by two photons at longer wavelengths and is no longer part of the radiation field. This is Raman-scattering.
Don’t know if this occurs, but seems identical to 2/. The 2 re-emitted photons are LW radiation and again atmosphere is transparent.
4/Other mechanisms for energy release are fluorescence and phosphorescence. These occur when the energy is not released spontaneously, but after relaxation times of nanoseconds to hours.
Is it possible? Additional informations needed.
5/Another basic type of interaction involves the conversion of molecular kinetic energy (thermal energy) into electromagnetic energy (photons). This occurs when molecules are activated by collisions with each other and the activation energy is emitted as photons. This is emission.
This is the mechanism of radiation emission by surface after solar irradiation. It is not possible to occur for the downwards LW photon as it has first to be absorbed by surface and 1/ prevents this absorption.
It seems that the only possible mechanism of interaction of the downwards LW photon with surface is the instantaneous re-emission of an identical LW photon. The atmosphere is transparent for this LW photon meaning that it escapes directly in space.
Feel free to add informations or correct.
Bye,
TMTisFree
Richard says:
Oh…Okay. Now I understand. This is the number for the amount by which we are ANNUALLY adding to the level of CO2 in the atmosphere. Yes, CO2 levels are increasing by somewhere around 1.5 ppm per year. (The number you quote is about double this because only about half of our emissions are accumulating in the atmosphere, with the other half being absorbed by the oceans and biosphere.) However, note that the amounts accumulate over time and what I was giving you was the total amount by which CO2 levels have changed as a result.
No serious scientist believes this garbage. It is based on measurements that are known to be bad…and involves believing that the carbon cycle behaved totally differently until Keeling started his measurements and then miraculously settled down. You are welcome to believe Beck if you want but you will not be taken seriously by anyone in the scientific community.
I don’t know what to tell you except that your calculation is completely and utterly meaningless. It is just numerology with absolutely no physical basis behind it.
Joel Shore,
“Having a certain pressure does not get you around having to obey radiative balance.”
Quite correct. The temperature at the top of the atmosphere is controlled by radiative balance, Stefan-Boltzmann, etc.
The difference between the top of the atmosphere and the surface temperature at the bottom of the atmosphere, however, is caused by pressure. It is the difference between the temperature predicted by pure radiative heat balance (about -18 C) and the actual observed temperature (about 14 C) that we refer to as “the greenhouse effect”. The emission to space is from the troposphere, and in the troposphere convection dominates, forcing the profile towards the moist adiabatic lapse rate. The lapse rate is because of pressure.
Without convection, and treating the atmosphere as a series of layers opaque to IR, then the business about each layer radiating at much up as down would mean that for each layer (~ 1 optical depth) you descend, the heat radiated would have to increase by an amount equal to the amount emitted to space at the top. With the increasing density making the layers thinner, this would rapidly lead to a ginormous temperature gradient. But in real air, the moment the gradient exceeds the adiabatic lapse rate, it becomes hydrostatically unstable, and turbulent convection quickly arises to correct the situation.
The absorption of IR and all the complicated MODTRAN quantum calculation of absorption/emission spectra is relevant to the question, because it determines where the IR radiates from. But because all this goes on in the convection-dominated troposphere, the mechanism by which a temperature difference arises is down to the pressure difference (modified by the heat carried by moisture) between the altitude at which IR radiates to space and the surface.
See here for Held and Soden 2000, look at figure 1 and the discussion just above and below it, to see the IPCC-cited version.
http://www.gfdl.noaa.gov/reference/bibliography/2000/annrev00.pdf
AJ Abrams,
Thanks for listening. It’s appreciated.
AJ Abrams says:
I didn’t skip your question. I just answered it at a more fundamental level. The question that you now ask is not well-defined. PV = NRT has four variables in it. Just specifying P does not allow you to uniquely determine T. The more fundamental physics determining T is that the planet must be in radiative balance with its surroundings.
Your talk about the pressure somehow explaining the high temperature makes no sense at all unless you are trying to suggest that the temperature on Venus is not governed primarily from the energy it received from the sun but is instead governed by radioactivity or continual gravitational collapse or some other form of energy. Good luck with that hypothesis! Such a notion was already dismissed in the mid-70s; see this 1975 paper linkinghub.elsevier.com/retrieve/pii/0019103576901573 entitled “Can internal heat contribute to the high surface temperature of Venus” that concludes:
“Fi = S/4 (1 – A) where S is TSI [1361 W/m2] and A is the albedo [=0.3].”
I stand corrected on the detail of energy input to the calculation.
Joel
Now you are being deliberately obtuse and condescending. Nobody, in their right mind could read what I wrote/asked and think :
“Your talk about the pressure somehow explaining the high temperature makes no sense at all unless you are trying to suggest that the temperature on Venus is not governed primarily from the energy it received from the sun but is instead governed by radioactivity or continual gravitational collapse or some other form of energy.”
In fact…the person that wrote back right above you had no problem at all understanding my question.
Thanks for not answering my question Joel. Please refrain from responding to my posts in the future.
To Stevo – Thank you. What you’ve said about convection made perfect sense and I’ll read your link shortly.
Leif Svalgaard @ur momisugly 09:27:52
Leif, if he accounts for albedo in the IN direction, why not for the OUT direction. Yes, I realise this is opening up a can of worms.
Global Warming Is A Hoax – Quick and Dirty
February 26, 2009
The facts that Al Gore’s carbon tax collection company doesn’t want you to see.
CO2 is 3.168% of the total greenhouse effect. Around 0.117% is man-made CO2 greenhouse gas effect. CO2 is an insignificant greenhouse gas, especially in terms of man-made contribution. Water is the only significant greenhouse gas
Furthermore, you leave out that oceans and volcanos release more CO2 than humans.
Furthermore, you leave out that CO2 is part of the life cycle.
Futhermore, you leave out that CO2 levels tend to follow warming rather than cause warming.
Furthermore, you leave out the impact of the sun spot activity, which is thoroughly studied, and it’s impact of warming/cooling on the solar system as a whole.
Furthermore, you leave out that the solar system as a whole had been warming.
Furthermore, you leave out that the solar system and earth has cooled down due to lack of sun spot activity this past year.
Furthermore, you leave out that carbon taxes will not solve the problem but will be used to fund global government and bombing of nations.
Furthermore, you leave out that big corporations, especially big oil, actually support the global warming hoax because it helps them eliminate their competition who can’t afford the taxes while big oil gets the big grants from the tax payer to reduce and meet emission standards.
Furthermore, you leave out that carbon taxes will do nothing but hurt the poor.
Furthermore, you leave out that polar bears can easily swim over 100 miles and swim as much as 300 miles. They hunt for seals and buluga whales.
Furthermore, you leave out that the ice caps are always melting and refreezing with the seasons.
Furthermore, you leave out that the government was caught making up temperature data to make it seem the planet was warming rather than cooling this past year.
Furthermore, you leave out that scientistics receive tons of funding by promoting global warming scares while skeptics don’t receive funding.
Furthermore, you leave out that the Al Gore hockey stick graph was generated using a statistical analysis computer algorithm that weighted data towards the mean the further out in history you go.
Furthermore, you leave out all the various drastic cooling and warming trends throughout the history of the Earth.
Furthermore, you leave out that global warming is actually preferred over global cooling because food production increases, namely because CO2 helps plant growth, absorbing that 0.117% man-made CO2 like candy. Not to mention that you’re more likely to freeze to death than die of heat stroke.
Furthermore, statistics are lies, lies, and damned lies. Scientific models don’t represent reality. Any decent college professor in scientific modeling and statistics classes will tell you these things on the first day of class.
In conclusion, you’re being scammed by the New World Order with this global warming hoax to pay carbon taxes to them, and you should be mad as hell.
Following up on my previous post, shouldn’t this 255K then represent the TOP of the atmosphere, not the surface, which would be warmer.
Robert Wood (11:34:12) :
if he accounts for albedo in the IN direction, why not for the OUT direction.
Because what comes in must go out eventually, so the IN-direction sets the amount.
Robert Wood (11:37:37) :
Following up on my previous post, shouldn’t this 255K then represent the TOP of the atmosphere, not the surface, which would be warmer.
The TOP of the atmosphere is out in space somewhere, but if we stick to the lower 10 miles or so, they are warmed from the surface, because the air is largely transparent to incoming radiation. Stand on a [tall] mountain, you get the same amount of incoming [actually a bit more – you sunburn quicker], yet it is usually cold up there, perhaps there is even snow on that mountain, but not down in the valley.