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.
Paddy,
The Martian atmosphere has very little water vapor, which is the most important greenhouse gas.
I find that spectral cooling chart fascinating. Is there a similar one for polar latitudes mid winter? The ozone, in particular. H2O is already going low in its impact at the ozone frequencies. In a cold polar winter, water ought to be even less of an impact.
So maybe this gives a mechanism for the sun modulating heat loss. Solar activity drives ozone (both up via UV and maybe charged particles (EFT); and down via GCR modulation). So there is this 10nm or so window controlled by the sun that waffles back and forth by 50% or so. And here we are stressing over a window at 7.5 that’s already well covered by water…
I know, it’s pure speculation. But just take a minute to look at that chart and ask yourself what happens as ozone wanders back and forth by 50 percent…
http://exp-studies.tor.ec.gc.ca/e/ozone/Curr_allmap_g.htm
doing a visual integration of the deviation chart further down the page I get about a 10% to 15% negative anomaly for the globe right now. It was even lower a few weeks ago when, surprise surprise, it was colder and snowing all over the place…
like this from January 3, 2009:
http://exp-studies.tor.ec.gc.ca/cgi-bin/selectMap?lang=e&type1=de&day1=03&month1=01&year1=2009&howmany1=1&interval1=1&intervalunit1=d&hem1=g&type2=no&day2=25&month2=02&year2=2009&howmany2=1&interval2=1&intervalunit2=d&hem2=n&mapsize=100
So I’m just left to wonder…
Joel Shore (11:12:12) :
Firstly, the sun has gradually brightened over time.
Yes. This is a system input. The fact that the system has not responded with runaway feedback over the variation of the sun’s input suggests the system is stable, not unstable.
Hansen argues that some negative feedbacks that operate at geologic timescales (mainly involving the GHGs themselves, I believe) could be inoperable here due to the very fast pace with which we are increasing the GHGs.
There are observations of past CO2 increases that were faster than todays. This line of reasoning is DOA.
But this begs the question, what is the water vapor/energy feedback relationship. Data analyzed by Roy Spencer indicates negative feedback. It suggests the system is not only stable, but resists change.
Furthermore, if water vapor feedback is negative, then the sensitivity is less than widely proclaimed 1 C per doubling CO2, and there is no cause for alarm. This is why I am a skeptic.
Today,we can save the world by reduce used something its harmful such as co2 from our car,reduce used oil and gas and reduce everything that make gobal warming.
Joel,
“The models and observations agree over the timescales for which the data is reliable but the observations disagree both amongst themselves and (in many cases) with the models over the timescales for which the data is known to have serious issues.”
So you’re saying models are in good agreement with, say, the last 10 years of temperature data?
I’m not sure that a statement such as yours, which indicates that when the models are wrong, it’s because the data is bad and when the models are right, it’s because the data is good, has much scientific credibility in the long run. (Although there are sometimes valid reasons why scientists try to use arguments like these, when looked back upon historically.)
Something was mentioned twice here that was never addressed by the normal folk that inhabit this site –
Pressure.
Does the temperature of Venus, Mars Jupiter atmosphere at 1ATM correlate to earth’s average temperature after adjusting for distance from the sun?
If it does, and I’ve now read two websites not related to climate science that say that it does, then the big…..OH…moment for me is that pressure regulates temperature more than any thing and that the ocean accounts for the rest of earth’s temperature variations over time – noting that the earths overall temperature doesn ‘t actually fluctuate by that much).
Also it says that SG’s comments about Venus and Mars are really misleading to say the least, which as a long time reader here, is disappointing.
Can someone clarify? Leif would be a prime candidate to answer because what I said would go along perfectly with his tireless shouts that IT’S NOT THE SUN! Which I believe
Bill Yarber (23:24:20) : Your use of Mars, Earth and Venus to prove that CO2 putis a major green house gas is totally flawed. You completely neglect their diameters and their distance from the Sun. Venus is 2/3s the distance from the Sun than earth and less than 1/2 that of Mars.
Don’t know what the diameter has to do with it (other than helping to retain more gas on heavier planets).
I’d have used moon / earth. Same distance from the sun is the same. It sure does get cold on the moon at ‘night’. Not sure how to handle the very hot ‘days’… Would be interesting to see what the ‘average’ does…
http://www.asi.org/adb/m/03/05/average-temperatures.html
says that it’s -35c below the surface. Probably a decent proxy for average…
That would give about a 45C heat gain for us from our atmosphere and vulcanism. And any differential albedo effects. Have no idea if that matches what any theory would predict. But I have trouble thinking that if the effect of the entire atmosphere is about 45C we could get more than 4C out of minor changes in one trace component…
Ergo, since the watts/sqm of the Sun’s out decreased with the square of the distance from the Sun, Venus gets over twice the energy that Earth gets and four times the energy Mars gets. Venus is warmer because it has a denser atmosphere and gets twice the energy Earth gets. This would be true if Venus had no CO2 in its atmosphere. Each planet has a different diameter but the difference is insignificant when compared to the impact of their individual orbit radii.
Bill
That ought to be (without Bill’s stuff at the bottom):
Bill Yarber (23:24:20) : Your use of Mars, Earth and Venus to prove that CO2 putis a major green house gas is totally flawed. You completely neglect their diameters and their distance from the Sun. Venus is 2/3s the distance from the Sun than earth and less than 1/2 that of Mars.
Don’t know what the diameter has to do with it (other than helping to retain more gas on heavier planets).
I’d have used moon / earth. Same distance from the sun is the same. It sure does get cold on the moon at ‘night’. Not sure how to handle the very hot ‘days’… Would be interesting to see what the ‘average’ does…
http://www.asi.org/adb/m/03/05/average-temperatures.html
says that it’s -35c below the surface. Probably a decent proxy for average…
That would give about a 45C heat gain for us from our atmosphere and vulcanism. And any differential albedo effects. Have no idea if that matches what any theory would predict. But I have trouble thinking that if the effect of the entire atmosphere is about 45C we could get more than 4C out of minor changes in one trace component…
Leif Svalgaard (17:31:15) :
Phil. (16:58:21) :
“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. ”
Even going along with that and that the N2 and O2 take up the heat, they in turn must re-radiate that heat [because they are now warmer], half up and half down [which then eventually heats the surface. Nothing changes with that, you still get a greenhouse effect.
Sorry N2 and O2 are homonuclear diatomics and don’t radiate.
Willis, 18:32:47:
I salute you again! LOL. We don’t know as much as we think we do. I’m going to go stick my feet in some hot water and check your facts…. 🙂
Fredrik Malmqvist (00:30:11) : Nils Bohr showed that gas molecules that absorb light are exited to a energy level and can only give off this energy with light at the same wavelength.
Um, I thought it was a bit more subtile than that. That two quanta could be absorbed, then emitted as one of higher energy, or that one could be absorbed, then emitted as two of lower energy, etc. Isn’t that how laser pumping works? Pump with UV, get IR laser light out, for example? And the exact quanta that can be absorbed are determined by the energy bands available for occupation in the electron shells of the atoms in question.
Or am I mixing up a long ago memory of physics that has moved on since they first discovered lasers…
(I also don’t know if this nit is relevant in the atmosphere at normal sunshine levels… just trying to find out if I’ve still got a grip on the physics…)
Will Nitschke says:
First of all, you are taking a statement out-of-context that I was using to talk about one issue in particular, the issue of tropical tropospheric amplification of temperature trends and fluctuations. Second of all, 10 years of data is insufficient to determine agreement or disagreement with the models for the global temperature trends because the error bar in the trend over such a time period is huge. Runs of climate models indeed confirm that one can expect some non-negligible fraction of periods of this length to show negative trends.
As I explained, there are independent reasons to believe that the data is questionable for the trends on the multidecadal timescales, not the least of which is that the two analyses of the same satellite data by two different groups yield very different results, one of which is essentially in agreement with the models within error bars and one of which is not. In general, one there is disagreement between observational data and models or theory, there is no hard-and-fast rule about which is right and which is wrong. It indicates the need for more work to try to resolve the discrepancy.
People are passing along all kinds of great ideas about feedbacks and second order effects which could reduce heating. Thanks for that.
But none of that changes the base properties of greenhouse gas warming.
Brief comments: from a hydro engineer involved in climate issues for 40 years:
– outstanding comments from peter taylor – I’m copying this for further consideration
– generally disappointing post with too many assertions and too little justification
– why is it hotter in the summer than it is in the countryP
re: John Peter
There is something I must be missing. The first page of your link indicates testimony before Sen. Boxer’s committee yesterday, February 26. But all the internal pages show a date of July 10, 2002.
Oh yeah, I forgot.
Every one of the analogies presented in this thread are pointless and irritating. Using analogies to discuss climate issues is like using a pincushion to deflate a pelican.
Personally, I’m getting very tired of the smug and sanctimonious comments from smart-ass know-it-all Lief
coaldust says:
I don’t want to spend a lot of time defending Hansen’s claim since I myself am skeptical of it and want to see his reasoning spelled out in more detail. However, I am also very skeptical of your claim about the speed of past CO2 increases. I don’t think there are faster increases in the ice core record and I don’t think that we have data resolved well enough in time before that to make such a conclusion.
First of all, let’s get our facts straight. Spencer is no longer questioning whether the water vapor feedback is negative. He now admits it is probably positive. What he is questioning is the cloud feedback. See his post here for explanation: http://www.drroyspencer.com/2009/02/what-about-the-clouds-andy/
Second of all, Spencer is just one scientist. You can always find a scientist to support just about any view if you look hard enough. (Actually, for the case of intelligent design, you need look no further than Spencer himself: http://www.tcsdaily.com/article.aspx?id=080805I ) And, Spencer has made some pretty bad errors in analysis when trying to get the answer that he seems to have a predisposition to want to believe (see here: http://tamino.wordpress.com/2009/01/19/a-bag-of-hammers/ ) Furthermore, there are lots of things that would need to be explained if Spencer is correct – i.e., all the observational evidence we have, e.g., paleoclimate data as well as the temperature response to the Mt Pinatubo eruption, that suggest that the climate sensitivity is in the range given by the IPCC. In fact, it becomes very hard to explain even the ice age – interglacial cycles.
If you were really a skeptic in the broader sense, you would be more skeptical of Spencer’s claims.
I like the feet in hot water experiment. That makes sense. It could also explain why a plausible CO2 mechanism does not pan out as a predictive closed model residing in a computer when compared to in-situ conditions and observations. The Earth is not capped by a firmament. It is an open, interconnected chaotic system. CO2 and its affects on water vapor, thus temperature, may indeed work one way in a petre dish, so to speak, but may work quite differently in the womb of Earth.
Elvis M says:
The best checks we have is the fact that there are some 10 – 20 different climate models floating around due to different groups of scientists. Many of them do not make their code publicly available. However, they do publish explanations of their algorithms and make data available for model intercomparisons. This is no different than any other field of the physical sciences that I’ve worked in. The NSF has been clear on the fact that use of their funds does not compel scientists to make their code freely available as they do retain their intellectual property rights over it.
This being said, the GISS Model E code is freely available and some others may be too.
It is also worth noting that the claim that AGW relies that heavily on the climate models, especially for the basic prediction of the magnitude of the warming expected, is overstated anyway. The IPCC’s estimate of the climate sensitivity is based mainly on observational data. In some cases, climate models are used to help interpret what sort of climate sensitivities that data implies…but they are not generally used directly to predict the climate sensitivity. (Although the range of climate sensitivities that exist in the current models do tend to mirror the range that is found to be most likely based on the observational data.)
Sure am glad there is some sort of greenhouse gas mixture in our atmosphere.
Otherwise, we’d all be frozen solid at night and fried during the day.
Sure is nice to have that blanket to nightly retain at least some of that precious energy coming from the Sun to keep warm.
Pamela: Have you ever considered taking rock temperatures 50 feet underground might tell us? They are known by miners (me included) to remain stable year round. If the Earth was warming or cooling over decades, this would surely show it.
RE: Steven Goddard (20:08:31) :
“People are passing along all kinds of great ideas about feedbacks and second order effects which could reduce heating. Thanks for that.
But none of that changes the base properties of greenhouse gas warming.”
Steve,
I posted earlier on vertical wind shear. Convective heat transfer is not a feedback and it is not a secondary order effect. It is a primary order effect and the dominant primary order effect at that. When things warm up they expand and what happens to warm air? Here’s another simpsons quote for you:
‘Heat makes metal expand? Now who’s talking mumbo jumbo?’
Bart Simpson
“If you want to make a knowledgeable argument, learn about the feedbacks.”
Two part YouTube video of Roy Spencer talking about feedbacks (Lindzen’s “Infrared Iris”) :
Why the IPCC models are wrong – Part 1
link
Why The IPCC models are wrong pt 2
link
Hi Joel,
I wrote: “So you’re saying models are in good agreement with, say, the last 10 years of temperature data?”
You wrote: “First of all, you are taking a statement out-of-context that I was using to talk about one issue in particular, the issue of tropical tropospheric amplification of temperature trends and fluctuations.”
Why do you say my remark is out of context? You were talking about models being in agreement with troposopheric temperature trends and I asked why you thought they were in good agreement, and you then complained I’ve changed the subject…? Odd… Could you clarify please?
“Second of all, 10 years of data is insufficient to determine agreement or disagreement with the models for the global temperature trends because the error bar in the trend over such a time period is huge.”
But the Santer paper was accepted for publication so the data he included in his analysis is thought to be sufficient. If even more data is included (adding the last few years to his data set), using his own methods, the models are not shown to be in agreement with predictions. Sorry, but on what reasonable basis do support your claim that models are doing well and we should have confidence in them?
“Runs of climate models indeed confirm that one can expect some non-negligible fraction of periods of this length to show negative trends.”
Obviously, but the larger that non-negligible fraction gets, the bigger the probability of the discrepancy being attributable to things other than ‘random weather noise’.
“In general, one there is disagreement between observational data and models or theory, there is no hard-and-fast rule about which is right and which is wrong. It indicates the need for more work to try to resolve the discrepancy.”
Generally speaking, in other research fields, your predictions need to conform with the empirical data before they are taken seriously. String theory, models of planetary formation, etc., require empirical confirmation, not the other way around. Climatologists invoke special pleading here for their own research work it seems… But let’s agree to disagree on that point.
Joel, may I ask if you have any association with what certain sceptics have referred to as the ‘Hockey Team’ ? Just curious, thanks.
My old friend Mr Shore said (09:01:02) :
“Diameter doesn’t matter.”
Please have a word with my doctor, Mr Shore, and stop him nagging me.