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.
““The surface of the Earth is warmer than it would be in the absence of an atmosphere because it receives energy from two sources: the Sun and the atmosphere.””
Boo, Joel!
Gerald,
I’m guessing you haven’t spent a lot of time at the beach in Northern California in the summer. Convective clouds are non-existent. Fog forms over the water and coast as soon as the air cools slightly, and only burns off for a few hours when the air temperature rises a few degrees. Some days the fog never lifts. I have a friend who paid his way through college at Berkeley selling sweaters to unprepared San Francisco tourists.
Gerald Machnee:
Thanks, your explanation is very much appreciated, but I understand that already.
My point, however clumsily expressed was that, making the most simplistic of comparisons with the moon, the surface temperature appears to be significantly cooled (rather then heated) by the atmosphere (and/or oceans) while in direct sunlight, and much warmer during the night hours.
My question is that, as peak surface temperature is much lower than it would be without an atmosphere, the mean average must surely be maintained by losing as little heat as possible during the period when the surface is not receiving SW warming.
Logically, I would assume that the bulk of this duty would be performed by the part of the system that is most efficient at storing heat, which is the oceans not the atmosphere.
If you, or anyone else can help me understand better whether my logic has any credible basis or not, that would be great!
Roger Sowell,
You are correct. The equation
outgoing radiation = incoming radiation – changes in oceanic heat content
shows that if “changes in heat content of the oceans” is positive, the amount of outgoing radiation is less than incoming.
lgl (14:17:20) :
Where do people get these ideas from? Googling the internet?
No ,this is textbook knowledge, which you usually embrace, why not this time?
Here is why [in answer to Phil]:
Phil. (09:56:18) :
The heat content of the air is 7/2kT per diatomic molecule (N2 and O2, which is essentially all there is). For each CO2 molecule there are about 3000 N2 and O2 molecules. About 4% of the CO2 molecules will be thermally excited at 300 K. The vibrational frequency of the bend in the molecule is 667 cm-1, kT at 300 K is about 200 cm-1, so the relative population will be exp(-667/200). Therefore, for each excited CO2 molecule there will be 75000 O2 and N2 molecules. The total heat content of those molecules will be 7/2 kT x 75000 ~ 5*10^6 cm-1 [The unit cm-1 as an energy unit is standard for spectroscopy]. The relative amount of deposited energy per excited CO2 is thus about 0.00001of the total energy. The temperature rise per CO2 excited is therefore negligible.
What an outstanding tutorial. Good concise use of Physics. Bravo!
John Galt, 114:45:30
Tonopah isn’t very far from Death Valley. Both are 100 miles from the nearest tree, 200 miles from the nearest water, and 6 inches to hell!
James Griffiths:
re the atmosphere cooling the surface while the sun is shining. This is incorrect. The atmosphere, like all things at non-zero (K) temperature, radiates heat. During the day, it still radiates heat. In fact the amount of heat the earth’s surface receives from the atmosphere is about twice the amount it receives from the sun. Although the sun is much hotter, it covers only a very small portion of the sky (90,000 suns would be required to cover the whole sky). A high intensity of radiation from the direction of the sun does not outweigh a small amount of radiation coming from the whole sky.
Re the article: “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.” Strictly speaking this is incorrect. Radiation is never re-emitted. The photons it comprises are absorbed (by clouds, CO2 or whatever) and their energy converted into kinetic and potential energy. Because the temperature of the cloud or whatever has then increased, it radiates more, so that new photons (at different wavelengths) are emitted.
Simon Evans: re the rapidity of previous temperature changes. The drop in temperature at the beginning of the Younger Dryas took place over only about a decade (see http://en.wikipedia.org/wiki/Younger_Dryas). How cold was it? Approx. 15C colder than today at the summit of Greenland. Mean temperature in the UK of around 5C. Different data sources suggest that the warming that ended the Younger Dryas (of around 10C +/- 4C) took either 40-50 years, in three discrete steps, or only a few years in total. Of course, there may have been species extinctions associated with these events. But there still seems to be a great deal of biodiversity.
Kevin dick,,
I am a Engineer with a degree in mathematics as well. I went over the Miskolczi’s differential equations, and I agree with his mathematics.
But the mathematics is dependent on the physical models that he postulates.
He is an empiricist as a Scientist, and simply looked at the satellite data reporting on the atmosphere, in his position at NASA. The data did not agree with the current GHG basis. That is based on radiation that Milne’s theory predicts and calculates.
His physical theory makes much more sense as a basis of planetary radiation theory. If Milne’s semi-infinite atmosphere model wasn’t the accepted and current theory it would be laughed off the stage as a ludicrous joke.
Just for kicks see if you can find the patch of Outer Space between your shoe-tops and the soles of your feet. If you can’t seem to find it, then Milne’s theory MUST be wrong. It is only that chunk of Space That MUST be there, that has prevented the Earth from descending into a global hell of catastrophic global warming eons ago, supplied with an infinite pool of GHG hydrogen dioxide. That is what the current theory predicts.
Miskolczi’s theory may not be totally correct, but it is a lot more rational than the current nonsense that passes as our accepted planetary atmosphere and its radiation balance. As an analogous example, Copernicus’ sun centered model was not fully correct. Kepler had to demonstrate that the planets were in elliptical not circular orbits, as Copernicus thought. But Copernicus’ model was much closer to reality than Ptolemy’s epicycles, with in epicyles, as a model of planetary movement about not the Sun, but the Earth.
O/T sorry:
I notice Spaceweather.com is still counting the sunspot #1013 which is now invisible.
How can an ex-micro-spec be counted as an SSN of 14.
Is this being counted by the official “spec”ulators?
Reed Coray (14:56:21) :
Since you ask questions I will respond to your post, despite your consistent use of the pejorative label ‘alarmist’ (I do not understand why this term is considered acceptable here. I do not label you or others whose views I do not share with pejorative terms).
the AGW alarmists had to adjust their “proof” when it was leanred that Antarctic temperature changes preceded Antarctic CO2 changes by approximately 1,000 years.
You don’t know your history. Milankovitch theory was well-supported by the 1970s ( the Vema 28-238 core and others having provided good verification), and the search then was for an explanation of how small solar variations could explain the extent of the glacial cycles. Scientists were considering positive feedbacks as an explanation in advance of discovering the relationship between temperature and CO2. When the Vostok cores were pulled up, by 1985, the correlation was evident, but it was always seen in terms of feedback. Your suggestion of an ‘adjustment’ in the argument is simply an invention.
So the AGW alarmists have increasing CO2 levels acting as both an originating and a feedback phenomenon. I’d like to know which if either is correct.
Both.
if both, then what stopped runaway global warming in the past?
The temperature feedback is less than the input.
If the larger temperature deltas at the system output are “fed back” into the system input, why won’t they cause even larger temperature deltas at the system output
They are not – at least, not fully. I don’t like the use of the term ‘feedbacks’ in climate science since it gives rise to this confusion, but I guess we’re stuck with it. Yes, CO2 induced warming may give rise to further increase in CO2 concentration, but is not likely to equal the ‘input’ (although some do consider the danger of methane release from the permafrost/sea bed, which I expect is what Hansen has in mind when he considers the possibility of a runaway effect if we were to burn all fossil fuels).
If it exists, I’d like to see a “circuit diagram” of the AGW alarmist’s temperature model where (a) the model inputs and outputs are defined, (b) all feed-forward effects (delays and multiplication factors) are shown, and (c) all feedback effects (delays and multiplication factors) are shown.
I’d recommend Chapter 8 of the AR4. It may not be quite in the form you want, but you can figure out answers to your questions:
http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter8.pdf
Steven: Good point.
No system is in thermodynamic equilibrium.
Time is not variable thermodynamics.
The Earth is an open thermodynamic system. (Possible decrease of entropy localized…ICE , urban heat island, life).
Steven Goddard (15:20:37) :
Gerald,
“I’m guessing you haven’t spent a lot of time at the beach in Northern California in the summer.”
Truthfully, I have been to LA but not San Francisco. However I do have pictures of the fog I use in presentations. Then I have to name the type of fog. I do not resort to Wikipedia much but I will quote the following:
The famous fog of San Francisco, California is a specific case of sea fog. Sea fog is a specific type of advection fog, which is characterized by the lateral transfer of temperature by wind blowing over cooler water. The water is often cool enough to lower the temperature of the air to the dewpoint, causing fog generation. Coastal areas in Mediterranean climates, such as San Francisco, have especially high occurrences of sea fog blowing off the ocean to just a few miles inland.
In San Francisco, the fog is created when warm, moist air blows from the central Pacific Ocean across the cold water of the California Current, which flows just off the coast. The fog can be very breathtaking if you are on the Golden Gate Bridge.
Temperatures can become very cold when the fog comes rolling in. Many people suggest you wear layers. Or, many fisherman sell thin, sweaters to people during the fog.
Correct me if I am wrong, but the deserts which are pretty cold in the evening have plenty of CO2. They are cold because of the absence of water vapor. What happened to the CO2 blanket?
The main cooling from the surface is actually weather: convection, cloud formation and precipitation. These are all poorly understood and there is little historical data to feed the models. In fact, if our atmosphere were static w/o weather and with the same amount of GHG as today, we would have 140 deg average surface temperatures. As for the Venus example, atmospheric pressure on Venus is enormous and it is much closer to the sun. Even w/o CO2 it would be blistering hot.
Since H20 is not present in significant amounts in the upper troposphere, where CO2 is presuambly well mixed, it would seem to me that atmospheric warming as a result of CO2 would show significant warming in the upper troposphere, yet we do not see this, do we? We do see stratospheric cooling as a result of higher CO2 levels. Could CO2 also be an important player in the cooling of the Earth (a negative feedback)?
In any event, nobody seriously argues that CO2 does not cause warming, just that it is not known how much, and the more CO2 there is, the less effect it has.
Your statement that “It is widely agreed that a doubling of CO2 will increase atmospheric temperatures by about 1.2C, before feedbacks.” is rather disturbing, as is your neglect to mention negative feedbacks. Widely agreed is just another term for consensus.
As for the stoplight analogy, you forget convection that allows the radiation to hop on the back of a CO2 molecule that runs through some or all of the red lights, although certainly higher CO2 levels mean that the heat removal takes place a bit slower, so perhaps a yellow liht anaology is more appropriate.
And this one: “increases in atmospheric temperature cause the ocean to warm up. Thus changes the oceanic heat content become the short term imbalance in the incoming/outgoing equilibrium equation”
If atmospheric temperatures rise first as a result of GHG, as they should, then the transfer of heat to cooler surface waters removes heat from the atmosphere. The ocean circulation allows the heat to be absorbed from the surface waters by the cold deep ocean. The heat capacity of the oceans simply dwarfs that of the atmosphere, so it is a great heat sink. But isn’t Hansen saying the heat is disappearing into the ocean, and then this heat will return somehow and heat the atmosphere?
A lot of my arguments came from Junk Science, so I really do not know what to make of this article.
“and the more CO2 there is, the less effect it has. ” should have said “and the more CO2 there is, the less affect more CO2 has”
pkatt wrote:
“Dave L I have a few questions for you:) (never met anyone with a greenhouse) In your greenhouse when you raise Co2 do you have to turn on the airconditioner? From day to night at an increased level of Co2 does your daytime temp spiral out of control unless you adjust it manually?.. And Im guessing you have to constantly replenish the Co2.. it just doesnt get there and stay does it?”
I realize pkatt is having a bit of fun here, but I think this is actually a very useful thought experiment, and, frankly, would be a useful actual experiment to perform. Construct a large greenhouse with significant vegetation, some arid areas and a large open water reservoir. Pump in a significant amount of CO2 and see if the temperature spirals out of control. If not, why not?
Now, this doesn’t mean that all the alleged horrors of AGW are false, after all, one could certainly posit all kinds of extreme weather events even without a runaway greenhouse effect. However, it should at least provide evidence that the runaway greenhouse effect, the infamous “tipping point” is a non-issue (as if any further evidence were needed).
Roger Knights (14:05:43) :
“Cap and trade” is a perfect example of a stealth tax on Americans. It is being sold as an ‘investment’; the gov’t would “invest” the “funds.”
In reality, cap and trade is a new way for the federal government to separate citizens from their money. And it is a lot of money — $645 Billion, that they admit to.
There would be a firestorm of protest if the government proposed a new $645 Billion tax increase. But when that tax increase is based on a completely non-existent problem — atmospheric carbon dioxide levels — then taking $645 Billion from people is A-OK.
0bama is slick. But he lacks honesty.
Alex` Heyworth (15:48:45) :
The drop in temperature at the beginning of the Younger Dryas took place over only about a decade (see http://en.wikipedia.org/wiki/Younger_Dryas). How cold was it? Approx. 15C colder than today at the summit of Greenland. Mean temperature in the UK of around 5C. Different data sources suggest that the warming that ended the Younger Dryas (of around 10C +/- 4C) took either 40-50 years, in three discrete steps, or only a few years in total. Of course, there may have been species extinctions associated with these events. But there still seems to be a great deal of biodiversity.
Indeed, but we’re not sure how global the effects were or, if they were, the pace of global change. There certainly is evidence for rapid regional changes in climate, as with Dansgaard-Oeschger events. In our own time regional temperature changes have far exceeded the global mean, of course. But basically I agree, that current climate change is not going to threaten the extinction of life on earth! Life will continue, but not, IMV, as we have known it. Some forms of life may flourish in warmer conditions and be able to take advantage of the pace of change. As for human society, I don’t fancy the implications of social disruption and conflict.
Alex Hayworth says:
“James Griffiths:
re the atmosphere cooling the surface while the sun is shining. This is incorrect. The atmosphere, like all things at non-zero (K) temperature, radiates heat. During the day, it still radiates heat. In fact the amount of heat the earth’s surface receives from the atmosphere is about twice the amount it receives from the sun. Although the sun is much hotter, it covers only a very small portion of the sky (90,000 suns would be required to cover the whole sky). A high intensity of radiation from the direction of the sun does not outweigh a small amount of radiation coming from the whole sky.”
Sure, but without an atmosphere, the surface temperature would be much higher during the day, right?
Anyway, clearly a high intensity of radiation form the sun does outweigh a small radiation from the whole sky, because the vast majority of the sky is only radiating because it has been heated by processes resulting from the heating of the surface by the sun. Am I correct?
I’m just an average joe here, but am I the only one that thinks that throughout the history of this planet, what we are doing now in this little tick of the geological clock is going to bring us all to ruination?
I do know that the climate of the Earth is changing constantly, and that it runs in cycles. Isn’t it the height of human hubris to think that we are changing the weather on this planet by accident while governments, countless scientists, and thinkers have been trying for years to change it on purpose?
From what I’ve seen, CO2 FOLLOWS climate warming; it isn’t the cause of it.
One element to the man-made global warming argument that gets no play whatsoever is the truth that man is a part of nature. The current argument seems to state that man is an alien invader to nature. In fact, we are PART of nature, not the controller of nature. Who is to say that our existence here isn’t as it is intended? Why is this a bad thing?
stas peterson (15:53:36) :
Heres a link too Miskolczi’s paper, http://met.hu/doc/idojaras/vol111001_01.pdf
For anyone who cares for a read, heres an article i also found under google on it http://constitutionallyright.com/2008/03/11/basic-greenhouse-equations-totally-wrong/
Im not qualified too comment 😉
I don’t remember using the word “catastrophe” or “catastrophic” in the article. I thought I was just writing a high level description of how the greenhouse effect works.
“Nobody expects the Spanish Inquisition”
– Michael Palin
This may have already been addressed. I haven’t read all 270 posts, but; The article states “… it is generally agreed that…” a doubling of CO2 will cause a 1.2 C rise in temps.
As far as I know, there is no engineering style study with empirical data verifying this hypothesis. Simply vague references to obscure and ancient textbooks are where you wind up when you follow the sources for this claim.
This radiative science boils down to the quantum physicists. Until one tells me that this 1.2 C hypothesis is indeed correct, I will wait for some rigorous science.
Leif Svalgaard (11:58:35) :
Phil. (09:56:18) :
near the surface any energy is exchanged via collisions with neighboring molecules almost immediately (timescale less than a nanosecond).
Where do people get these ideas from? Googling the internet? How about some thinking?
Try teaching ‘Physics of Gases’ at the graduate level for over 10 years!
Any CO2 molecule which absorbs an IR photon will be rotationally/vibrationally excited, the radiation lifetime of that excited state is order microseconds or greater whereas the average time between collisions is less than 1 nanosec. Consequently the excitation energy will be preferentially lost via collisions (quenching). At higher altitude (lower pressure) the lower collision frequency means that the possibility of emission of a photon increases, hence fig 3 above.
David Porter (14:17:32) :
foinavon (10:14:41) :
Not really David. It’s not really about “theories”. It’s about the evidence, and the evidence certainly doesn’t come from just the past 8 years. The evidence for a climate sensitivity around 3 oC (temp rise per doubling of atmospheric CO2) goes back a long way (at least 20 years in the “modern” era, and even in the 1960’s the climate sensitivities were estimated to be in the range 1 – 4.5 oC). Callendar determined a value of 2 oC in 1938. The large majority of measures of climate sensitivity determined/estimated in the last 40 years have been in the range 1.5 – 6 oC (the top limit has always been difficult to pin down), and the more recent analyses just help to confirm the nature of the evidence and to narrow down the range to a higher likelihood that it’s between 2 – 4.5 oC at equilibrium.
So if we’re going to consider the climate sensitivity we really should consider the evidence as it stands. It doesn’t seem very professional to use as an illustration of climate sensitivity, a plot from a website called “junk science” which shows some rather odd data (the Charnock-Shine data seems to be incorrect as assessed by what Charnock-Shine actually reported….the Kondratjew and Moskalenko data is from an obscure 25 year old Russian report and the Lindzen data uses asumptions that we know are incorrect).
I can’t understand how you can be suspicious of newish science. Especially in reviews that address a compilation and synthesis of all the evidence, one expects that the most recent work is likely to be at least as good as earlier work and likely to conform to an increase in our understanding. Of course very recent single papers that might be provocative or especially novel, might well be looked at with reasonable skepticism until their essential points are confirmed. But that’s certainly not the case with the climate sensitivity.
…and as you can see I haven’t chosen to include Hansen’s interpretation of a rather high climate sensitivity (around 6 oC) that he and colleagues consider likely in relation to very long scale feedbacks involving the oceans and ice sheet dynamics…