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 ,
This article is intended to be a qualitative overview, not quantitative. The figure just shows that noted skeptic Lindzen believes that increasing CO2 will lead to increasing temperature. As does Spencer, Pielke, etc……
Regarding relative humidity and temperature, I’ve noticed RH will often begin to show decline preceding a temperature drop, and then as temps fall RH tracks with it. Having lived much of my time in northern Alaska temperature is an interesting subject…will it be just -20F or should we prepare for -50F. The thing I have come to watch as first sign is whether RH is starting to drop off on a cold night, and keeps dropping as temps fall, to get an idea if it will be cold (superstition?). I’ve wondered if there was such a thing as “apparent” RH when temps are low that confuses the issue. Has anyone else noticed or have an explanation for this seeming not inverse relationship between RH and temp?
Re:Frank Lansner (04:05:14) :
I’m pleased to see that someone finally mentioned the most significant reason for the differences between the atmospheric temperatures at the surface of Mars and Venus relative to Earth.
Does anybody out there remember what Boyle’s Law describes? In regard to gasses, it was a staple of high-school phsyics when I went to school (over 50 years ago).
It’s PV = nRT
Since n and R are constants, the product of the variables P (pressure) and V (volume) are proportional to T (temperature). That means that if you hold the volume of a gas constant, Temperatures will rise or fall in reponse to like changes in pressure.
The temperature at the surface of Venus is about 465°C as compared to a mean temperature of the Earth of about 15°C. The surface atmospheric pressure on Venus is 92 bars vs a mean pressure of about 1 bar at the Earth’s surface. So one could relate the high surface temperature on Venus to the fact that it’s surface pressure is 92 times that on Earth.
Similarly, the the atmospheric surface pressure on Mars is 0.006 bar or about 6/1000ths the pressure on Earth. The mean surface temperatures ia bout -46°C.
The atmospheres of both Venus and Mars are about 95-97% CO2.
The constituency of the various atmospheres have a lot to do with the Planets’ gravity, a function of its mass. None of these Planets are capable of holding onto hydrogen or helium which have a low escape velocity because of their low mass. Earth’s gravitation is strong enough to hold both oxygen and nitrogen and all three Planets…Mars, Venus and Earth can hold CO2.
Incidentally, a Planet as massive as Jupiter has an atmosphere that’s essentially 100% hydrogen.
If one looks at the upper atmosphere of Venus at a height where the pressure is about the same as at the Earth’s surface….1 bar…guess what? The mean temperature at that level is about the same as on Earth.
Venus lies close enough to the sun so that solar energy is strong enough to vaporize water leaving no significant amounts of compounds in which CO2 can readily dissolve, so once created, it remains in and comprises most of the atmosphere.
As for other non GH gases like Nitrogen (N); although N is only about 3% of Venus’s atmosphere, there is actually 4 times as much N in Venus’ atmosphere as there is on Earth despite the fact that Earths atmosphere is about 79% N. It’s a matter of the density difference.
Despite the attribution by many that Venus’ high surface temperature is a result of the GH effect due to its CO2 rich atmosphere, one might ask why then isn’t Mars (with more CO2 in its atmosphere than here on Earth) warmer than it is? It’s the sun……
In summation, there are lots of other aspects of physics and thermodynamics that have yet to be fully reconciled before a conclusion that GW in general and AGW in particular is responsible for temperature stability, or even more dubious, will be reponisble in the future for Global Warming.
Steve’s primer offers nothing new to the AGW argument.
Another exercise that I would suggest people try periodically is to use Weather Underground to compare the daily weather histories for two contrasting locations. As an example look at the record for Tamanrasset Aguenna, Algeria http://english.wunderground.com/history/airport/DAAT/2009/2/26/DailyHistory.html?req_city=NA&req_state=NA&req_statename=NA
and Mombasa, Kenya http://english.wunderground.com/history/airport/HKMO/2009/2/26/DailyHistory.html?req_city=NA&req_state=NA&req_statename=NA .
Tamanrasset Agenna has a relative humidity of around 10% and Mombasa has a relative humidity of around 94%. Notice the temperature changes between midnight and 7am at both locations. The location with highest humidity should cool the least because of the greenhouse effect. Now we must realize that there are other conditions that can affect the temperature changes between the locations, but if you do this little exercise hundreds of times like I have trying to find locations of similar elevations and alike in all respects but humidity you will begin questioning the importance of the greenhouse effect. We may not see the forest for the trees. Actually if you see this, http://www.telegraph.co.uk/earth/environment/globalwarming/4839985/Scientists-to-stop-global-warming-with-100000-square-mile-sun-shade.html , you might agree that man is rapidly moving back to the trees.
Steven:
Steven Goddard (05:51:38) :
Ric,
I did a canoe trip down the Green River in Utah about 25 years ago in July. It was too hot to sleep when you went to bed, and too cold to sleep when you woke up!
You seem to be confusing evaporation from the river with lower humidity.
Having lived in the desert for 54 years I can say that Jae is correct.
I rode bicycles through the desert at night and new where all the underground streams were by the loss of warmth.
Steve Goddard,
Thank you to you and Anthony for posting this, as it does explain many things. However, I believe there is a discrepancy.
You wrote: “The radiative balance has to be maintained in the atmosphere, so the outgoing radiation has a fixed amount of time to escape, regardless of how many GHG molecules it encounters. Otherwise, Homer and your boss will be very angry at you for violating the laws of thermodynamics.”
It appears to me that the global radiative balance cannot be maintained in the atmosphere, as suggested above, if the atmosphere and oceans are to increase in temperature over time due to greenhouse gas effects.
Surely, a hotter atmosphere implies more energy per molecule, and that energy is heat. The same is true for the oceans. Thus, as long as the globe is warming, the input of energy to the earth must exceed the output.
If the GCMs have the energy input equal to the energy output, then that is another bust in the models.
One could argue that the difference is negligible, (input-output) as the earth is very large in mass. I have not run the calculations to confirm.
The first and second laws of thermodynamics require an imbalance between input and output for global warming.
To make this perfectly clear, the normal energy balance equation for a body is:
(mass IN x heat content IN) + (radiation IN) + (heat generation) =
(mass OUT x heat content OUT) + radiation OUT + (heat accumulation)
where:
mass IN and OUT are in pounds per hour, (negligible for the Earth)
heat content is in BTU per pound,
radiation is in BTU per hour,
heat generation is in BTU per hour, and
heat accumulation is in BTU per hour. (British units used)
Also, heat accumulation can be either positive or negative. Heat accumulation is required for the Earth to grow warmer.
Heat generation may be, for the Earth, nuclear power, burning fossil fuels, volcanic and geothermal effects, but not wind power or wave power.
Best discussion I’ve seen here.
Relatively free of political science and snarkiness.
It’s obvious from these posts that belief in this 19th century piece of nonsense is very persistent. Many people are still willing to make excuses for this nutty theory, like astrologers loading more corrective epicycles onto a Ptolemaic model. Given what’s known today about thermodynamics, however, had no one ever heard about a “greenhouse effect” before, no physicist would be foolhardy enough to propose one to explain the earth’s temperature.
Please excuse my layman’s level of understanding. I am confused by conflicting statements about CO2 levels historically. Steve states that atmospheric CO2 was about 200ppm 14,000 years ago. Dr Will Happer testified before a Congressional committee today (See ICECAP “Scientist tell Congress: Earth in CO2 Famine”). He stated:
“Many people don’t realize that over geological time, we�re really in a CO2 famine now. Almost never has CO2 levels been as low as it has been in the Holocene (geologic epoch) – 280 (parts per million – ppm) – that’s unheard of. Most of the time [CO2 levels] have been at least 1000 (ppm) and it’s been quite a bit higher than that, . . .”
“Earth was just fine in those times,” Happer added. “The oceans were fine, plants grew, animals grew fie. So it’s baffling to me that we’re so frightened of getting nowhere close to where we started,” Happer explained. Happer also noted that “the number of (skeptical scientists) with the courage to speak out is growing” and he warned “children should not be force-fed propaganda, masquerading as science.” In December, Happer requested to be added to the groundbreaking U.S. Senate Minority Report Update: More Than 650 International Scientists Dissent Over Man-Made Global Warming Claims
“Happer was pressed by the Committee on whether rising CO2 fears are valid. “I don’t think the laws of nature or physics and chemistry has changed in 80 million years. 80 million years ago the Earth was a very prosperous palace and there is no reason to suddenly think it will become bad now,” Happer added. Happer is a professor in the Department of Physics at Princeton University and former Director of Energy Research at the Department of Energy from 1990 to 1993, has published over 200 scientific papers, and is a fellow of the American Physical Society, the American Association for the Advancement of Science, and the National Academy of Sciences. Happer was reportedly fired by former Vice President Al Gore in 1993 for failing to adhere to Gore’s scientific views.”
So what was the CO2 concentration 14,000 years ago? If the low end historically is 280ppm, we should be working actively to increase CO2 levels to 1000ppm.
I know that mine safety rules allow for extended exposure to 3000ppm and US Navy allows submarine air to have up to 5000ppm. This should exclude concerns of danger to animal and plant life.
It seems that that no research has been conducted to determine the optimum CO 2 level or the amount below which it becomes dangerous.
Clear up my confusion and ignorance please.
Can somebody tell me what’s wrong with this critical examination of the traffic light analogy:
In the traffic light analogy, the energy is driving from point A (the outside extreme of the atmosphere) to point B (the surface). The author’s point is that the commute takes longer, and since the driver spends more time driving, this equates to an increase in heat.
The problem I have with the analogy is that the energy can only go in one direction. The reality is that when the energy is absorbed (stopped at a light), and emitted (the light turns green), it can be emitted in any direction, including back out towards space. It would be as if to say that there is a 50% chance at every light that the driver will get frustrated waiting for the light to change, and turn around and leave before dropping the kid off for school. Now, at every subsequent light, in each direction, the same choice is made.
It seems to me light as you increase the number of traffic lights (CO2 molecules), the more heating you’d get in the upper atmosphere, and the less would eventually make it to the surface; and here is why – as you approach the surface, the density of the atmosphere (and therefore CO2) increases (more chance to get turned back) – as you travel away from the planet, the density decreases (less chances to get turned back).
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?
Here goes: 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.
Goddard you ~snip~ , when CO2 emits LW radiation it is at a frequency it cannot then reabsorb.
Cripes alive.
Steven,
the IPCC describes the forcing for a doubling of CO2 as 3.7 watts/m2. When I do the maths, that comes out at a fraction over 1 degree Kelvin. A tad lower than your claim of 1.2K.
The problem with this forcing is the still unexplained cooling period that started in the 40s through to the mid 70s. There just isn’t enough aerosol pollution to justify the masking claim by Jim Hansen and others.
However, the 3.7 watts/m2 is simply a hypothesis described by a one-shell model of the Earth’s atmosphere. If we add increased complexity to the model, the forcing for a doubling of CO2 reduces in effect. A lower forcing of say 2.3 watts/m2 gives approx. 0.6K for a doubling of CO2. That would explain more effectively the post-war dip in temperatures rather than relying on the aerosol handwaving.
There is also another logistical problem I have with the positive feedbacks claims. Atmospheric CO2 increases have a near instantaneous effect on temperature. We also know that CO2 effect on temperature is logarithmic so currently we have seen 60% of the forcing that a doubling of CO2 brings. So where are these positive feedbacks? There should be greater evidence of these occurring than the actual empirical data shows.
Also positive feedbacks build upon themselves. This stoppage in temperature rises cuts off that process. If natural variations have that effect then the positive feedbacks have to be considerably weaker than is assumed.
Sir, you are a complete tool of the international banking cartel and corporate fascists. They want carbon taxes not to fix the environment but to fund global government … to enslave the labor of the world, to steal the resources of the world without competition, and to bomb nations who don’t submit to their empire. Taxes do nothing but hurt the poor.
You, like all the other tools conveniently leave out the percentage of greenhouse effect from CO2 and other greenhouse gases. CO2 is roughly 3% of the total greenhouse effect. Around 0.2% is man-made CO2. CO2 is an insignificant greenhouse gas, especially in terms of man-made contribution. Water is the only significant greenhouse gas.
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. Futhermore, you leave out that from the data that CO2 levels tend to follow warming rather than cause warmer.
Statistics and models are lies, lies, and damned lies. Any decent college professor in scientific modeling and advanced mathematics will tell you that.
~snip~
Can anyone explain how the man-made portion of atmospheric CO2 is responsible for GLOBAL temperature change? The UN estimate of man-made CO2 is: 0.000348% by volume: “Mass of Global Atmospheric Gases” chart.
http://lce.folc.ca/2008/08/03/man-made-global-co2-emissions/
Then, factoring CO2 absorbtion of IR of about 8% spectrum yields the volume of atmosphere with sensitivity to thermal absorbtion is 0.00002785. Or, what have I done wrong?
Peter (06:36:58) :
I’ve been led to understand that the CO2 released by man-made activities represents about 3% of the atmospheric CO2. Can anyone attest to the accuracy of that claim?
That comes from the IPCC, Climate Change 2001.
So I won’t attest to its accuracy.
http://morethanamolehill.wordpress.com/2007/09/25/you-want-to-save-the-world-compost/
Time spent at stop lights is ttotal = n * tlight where n is the number of stop lights.
light absorbed by a column of air is Atotal = 1-exp(-(a1*c1+a2*c2+…)*l) where a is an absorption coefficient, c is a concentration and l is the length of the column.
So this is not a good analogy. Because the absorbed light is re-emitted and re-absorbed, I’m not saying that adding more GHG to a saturated system will not result in less energy emitted to space, but adding more should have a diminishing effect.
Johnski,
You are correct about the narrow band of CO2 absorption/emission frequencies, but there are other greenhouse gases in the atmosphere besides CO2, which interact with each other. If you note from the spectral diagram above, H2O absorbs nearly continuously across the spectrum. No need to get snippy.
The facts that Al Gore’s carbon tax collection company doesn’t want you to see.
CO2 is roughly 3% of the total greenhouse effect. Around 0.2% is man-made CO2. 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.
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.
Futhermore, you leave out that CO2 levels tend to follow warming rather than cause warmer.
Furthermore, you leave out that carbon taxes will not solve the problem but will fund global government and help big corporations to eliminate the competititon.
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 solar system has 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 the government was caught making up temperature data.
Furthermore, you leave out that scientistics receive tons of funding by promoting global warming scares while skeptics don’t receive funding.
Statistics and models are lies, lies, and damned lies. Any decent college professor in scientific modeling and advanced mathematics will tell you that.
delete my post, i’m entering you into a database of obvious foundation funded criminals engaging in high crimes of fraud and corruption when the people wake up to the truth and tear down the new world order to stop global enslavement and global depopulation by the international banking cartel.
~snip~ [Please, if you disagree explain why, but don’t call other commenters liars here.]
I agree with Steven Goddard that it is all about feedbacks. The case against the existence of positive feedback, however, is extremely strong. Positive feedback means an internal amplification factor greater than 1, which means a self reinforcing, runaway process. Best example of such a process is a chemical – or nuclear – explosion. There are many arguments against the Earth’s climate being a system that is controlled by positive feedback.
1., Historical evidence. There is no evidence in climate history, that temperature swings are being reinforced by positive feedback leading to runaway climatic changes. The most recent examle was the 1998 El Nino event, which generated an almost 1degree C spike in global temperature in less than one year. If positive feedback were to be present, the temperature would have kept climbing. Instead, after the El Nino was over, temperatures returned to their pre El Nino values.
2., Recent work by Dr. Roy Spencer, who, based on his research, in his recent congressional testimony stated, in front of Senator Boxer, that there is no positive feedback in the ( Earth’s ) climate. I guess he was willing to risk the charge of perjury.
3., Dr Hansen’ circular argument. He is clearly worried about a Venus like runaway heating caused by positive feedback. At the same time, he is postulating that positive feedback is already the operating principle of the Earth’s climate as witnessed by his projected climate sensitivity factor of 6.5, which implies existence of a strong positive feedback. If this were the case, we are already doomed. There is no magic “tipping point” . A positive feedback driven runaway process cannot be stopped any more than a nuclear explosion can be stopped halfway through the process.
foinavon (10:14:41) :
Kondratjew and Moskalenko (+ 1.75 oC per quadrupling of CO2)
I can’t find a paper by these two in the database. I’ve tried some alternative spellings without luck. Could you please clarify the citation?
Kondratyev and Moskalenko 1983, 1984 These are in Russian,though translated extracts are in Houghton 1985
Essentially these are radiative/convection models similar to Ramanathan 1976,and as such more accurately ascertain for dissipation eg Landau and Lifshitz 1965(ie mathematically correct) as opposed to the empirical methodology used in GCM(where they “appeal” to a closure relation )
EG http://i255.photobucket.com/albums/hh133/mataraka/ramanathanco2x.jpg
Joel Shore (09:01:02) :
I turned to Professor James Hansen, the director of Nasa’s Goddard Institute for Space Studies, whose climate calculations have proved to be more accurate than anybody else’s. He believes the melting of the Greenland ice cap being picked up by his satellites today, now, suggests we are facing a 25-metre rise in sea levels this century – which would drown Bangladesh entirely.
Bangladesh is set to disappear under the waves by the end of the century
Scary. Citation and a confirming letter from Dr. Hansen found here:
American Thinker
but wait:
Bangladesh landmass is growing
Not so scary.
tmtisfree:
The re-radiation doesn’t additionally warm the surface, but rather slows down the rate at which the surface loses heat – thereby keeping it warmer for longer than it would otherwise have been.
However, it only slows down the rate at which the surface loses heat by radiation – it doesn’t affect the rate of heat loss from conduction, convection or evaporation.