Does CO2 Drive the Earth’s Climate System? Comments on the Latest NASA GISS Paper
by Dr. Roy Spencer
There was a very clever paper published in Science this past week by Lacis, Schmidt, Rind, and Ruedy that uses the GISS climate model (ModelE) in an attempt to prove that carbon dioxide is the main driver of the climate system.
This paper admits that its goal is to counter the oft-quoted claim that water vapor is the main greenhouse gas in our atmosphere. (They provide a 1991 Lindzen reference as an example of that claim).
Through a series of computations and arguments, the authors claim that is actually the CO2, not water vapor, that sustains the warmth of our climate system.
I suspect this paper will result in as many opinions in the skeptic community as there are skeptics giving opinions. But unless one is very careful in reading this paper and knows exactly what the authors are talking about, it is easy to get distracted by superfluous details and miss the main point.
For instance, their table comparing the atmospheres of the Earth, Venus, and Mars does nothing to refute the importance of water vapor to the Earth’s average temperature. While they show that the atmosphere of Mars is very thin, they fail to point out the Martian atmosphere actually has more CO2 than our atmosphere does.
I do not have a problem with the authors’ calculations or their climate model experiment per se. There is not much new here, and their model run produces about what I would expect. It is an interesting exercise that has value by itself.
It is instead their line of reasoning I object to — what they claim their model results mean in terms of causation– in their obvious attempt to relegate the role of water vapor in the atmosphere to that of a passive component that merely responds to the warming effect of CO2…the real driver (they claim) of the climate system.
OUR ASSUMPTIONS DETERMINE OUR CONCLUSIONS
From what I can tell reading the paper, their claim is that, since our primary greenhouse gas water vapor (and clouds, which constitute a portion of the greenhouse effect) respond quickly to temperature change, vapor and clouds should only be considered “feedbacks” upon temperature change — not “forcings” that cause the average surface temperature of the atmosphere to be what it is in the first place.
Though not obvious, this claim is central to the tenet of the paper, and is an example of the cause-versus-effect issue I repeatedly refer to in the past when discussing some of the most fundamental errors made in the scientific ‘consensus’ on climate change.
It is a subtle attempt to remove water vapor from the discussion of “control” over the climate system — by definition. Only those of us who know enough of the details of forcing-feedback theory within the context of climate change theory will likely realize this, through.
Just because water vapor responds quickly to temperature change does not mean that there are no long-term water vapor changes (or cloud changes) — not due to temperature — that cause climate change. Asserting so is a non sequitur, and just leads to circular reasoning.
I am not claiming the authors are being deceptive. I think I understand why so many scientists go down this path of reasoning. They view the climate system as a self-contained, self-controlled complex of physically intertwined processes that would forever remain unchanged until some “external” influence (forcing) enters the picture and alters the rules by which the climate system operates.
Of course, increasing CO2 is the currently fashionable forcing in this climatological worldview.
But I cannot overemphasize the central important of this paradigm (or construct) of climate change theory to the eventual conclusions the climate researcher will inevitably make.
If one assumes from the outset that the climate system can only vary through changes imposed external to the normal operation of the climate system, one then removes natural, internal climate cycles from the list of potential causes of global warming. And natural changes in water vapor (or more likely, clouds) are one potential source of internally-driven change. There are influences on cloud and water vapor other than temperature which in turn help to determine the average temperature state of the climate system.
After assuming clouds and water vapor are no more than feedbacks upon temperature, the Lacis et al. paper then uses a climate model experiment to ‘prove’ their paradigm that CO2 drives climate — by forcing the model with a CO2 change, resulting in a large temperature response!
Well, DUH. If they had forced the model with a water vapor change, it would have done the same thing. Or a cloud change. But they had already assumed water vapor and clouds cannot be climate drivers.
Specifically, they ran a climate model experiment in which they instantaneously removed all of the atmospheric greenhouse gases except water vapor, and they got rapid cooling “plunging the climate into an icebound Earth state”. The result after 7 years of model integration time is shown in the next image.
Such a result is not unexpected for the GISS model. But while this is indeed an interesting theoretical exercise, we must be very careful about what we deduce from it about the central question we are ultimately interested in: “How much will the climate system warm from humanity adding carbon dioxide to it?” We can’t lose sight of why we are discussing all of this in the first place.
As I have already pointed out, the authors have predetermined what they would find. They assert water vapor (as well as cloud cover) is a passive follower of a climate system driven by CO2. They run a model experiment that then “proves” what they already assumed at the outset.
But we also need to recognize that their experiment is misleading in other ways, too.
First, the instantaneous removal of 100% of the greenhouse gases in the atmosphere except for water vapor causes about 8 times the radiative forcing (over 30 Watts per sq. meter) as does a 100% increase in CO2 (2XCO2, causing less than 4 Watts per sq. meter), something that will not occur until late this century — if ever.
This is the so-called ‘logarithmic effect’…adding more and more CO2 has a progressively weaker radiative forcing response.
Currently, we are about 40% of the way to that doubling. Thus, their experiment involves 20 times (!) the radiative forcing we are now experiencing (theoretically, at least) from over a century of carbon dioxide emissions.
So are we to assume that this dramatic theoretical example should influence our views of the causes and future path of global warming, when their no-CO2 experiment involves ~20 times the radiative forcing of what has occurred to date from adding more CO2 to the atmosphere?
Furthermore, the cloud feedbacks in their climate model are positive, which further amplifies the model’s temperature response to forcing. As readers here are aware, our research suggests that cloud feedbacks in the real climate system might be so strongly negative that they could more than negate any positive water vapor feedback.
In fact, this is where the authors have made a logical stumble. Everyone agrees that the net effect of clouds is to cool the climate system on average. But the climate models suggest that the cloud feedback response to the addition of CO2 to our current climate system will be just the opposite, with cloud changes acting to amplify the warming.
What the authors didn’t realize is that when they decided to relegate the role of clouds in the average state of the climate system to one of “feedback”, their model’s positive cloud feedback actually contradicts the known negative “feedback” effect of clouds on the climate’s normal state.
Oops.
(In retrospect, I suppose they could claim that cloud feedbacks switched from negative at the low temperatures of an icebound Earth, to being positive at the higher temperatures of the real climate system. But that might mess up Jim Hansen’s claim of strongly positive feedbacks during the Ice Ages).
CONCLUSION
Taken together, the series of computations and claims made by Lacis et al. might lead the casual reader to think, “Wow, carbon dioxide really does have a strong effect on the Earth’s climate system!” And, in my view, it does. But the paper really tells us nothing new about (1) how much warming we can expect from adding more CO2 to the atmosphere, or (2) how much of recent warming was caused by CO2.
The paper implies that it presents new understanding, but all it does is get more explicit about the conceptual hoops one must jump through in order to claim that CO2 is the main driver of the climate system. From that standpoint alone, I find the paper quite revealing.
Unfortunately, what I present here is just a blog posting. It would take another peer-reviewed paper that follows an alternative path, to effectively counter the Lacis paper, and show that it merely concludes what it assumes at the outset. I am only outlining here what I see as the main issues.
Of course, the chance of editors at Science allowing such a response paper to get published is virtually zero. The editors at Science choose which scientists will be asked to provide peer review, and they already know who they can count on to reject a skeptic’s paper.
Many of us have already been there, done that.
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Thanks to Dr. Spencer for a very readable, informative, and irenic discussion.
Lately it’s occurred to me that a genuine open-minded attitude toward climate-change issues may actually be more of a threat to the “consensus” position than a resolute resistance to that position.
Lately I’m also regarding Steve McIntyre and Roy Spencer as a couple of real-life heroes.
I think the cleverest part of the paper was the ‘balance’ diagram. This type of diagram has probably never appeared in a scientific journal before, though such diagrams are occasionally included in pieces intended to encourage school children to eat a small amount of protein with their refined sugar.
Aside from that, the paper demonstrated that the model’s assumption is that CO2 is ‘the’ thermostat. But, one would have thought that this was fairly obvious, given that the model has been used to create enumerable CO2 based CAGW scare stories.
If they had explained the “travesty” (team member Trenberth’s word) of the current lack of warming despite the ongoing CO2 rise (which the model fails to predict) now that would have been intriguing – but, sadly, they did not.
Dr. Spencer–
Thanks for hitting the nail on the head. I’ve been arguing this for ages. A simple troubleshooting technique is to check the operating conditions before a change was observed, then check what changed.
In the case of chemistry (my subject), a reaction that has been run hundreds of times before stops working. So we check each reagent’s purity, and then purify each reagent to see if it starts up again. It’s a simple system since if one variable changes, we can assume the other variables are static.
It’s the same differentials used in medicine. What factors are different that caused the problems? Then isolate the problems.
Unfortunately, the same methods cannot be applied to climate change. CO2 has increased, but the temperature increase has not been consistent. In addition, there’s also a correlation between El Nino and global temperature. The sun’s influence on climate is not completely understood, as well as deep ocean currents and heat exchange between layers in the ocean.
Effectively, it’s much like diagnosing a patient with the flu after the patient experienced a fever. However, the patient recently traveled across SE Asia and Africa. The patient also complained of lower back pain before the fever, and the back pain still persists. Not to mention the patient has tested positive for an STD and a genetic disorder. What is really causing the fever?
Now, I’m not saying the Earth has been sleeping around and has bad genes. But incomplete troubleshooting usually doesn’t solve a problem. I’ve seen this time and time again. Over-simplification of climate science doesn’t prove anything, especially pulling out something as important as water vapor.
Thanks for another fine exposition of the inherent fallacies of this line of reasoning. From occasional browsing at RealClimate, I have noted the many times that Gavin Schmidt of GISS has made the same statements that water in its various forms simply follows the effects of carbon dioxide and other GHG’s. The chaotic forces of our weather systems involving the many forms of water are simply ignored.
They could have checked to see how their theory jibes with the real world of the last decade but that is how real science works and only spelling connects climate -science to real science these days. Pity
Failure to quantify H2O forcings, as well as cloud reflections from incoming sunlight, means that the conclusions also lack CO2 quantitative forcings. No process of elimination = no solid basis of proof.
Jack Eddy is grinning as zero weight to paper.
Dr. Spencer
At the risk of being blunt I comment as follows.
The authors of this paper have conducted a thought experiment, the fact that they used a calculating machine to carry out the necessarily complex mathematical work is neither here nor there.
A thought experiment is only of any use if its conclusions are capable of being verified or falsified by observation in the real world. Physicists do exactly that which is why we have the LHC. And we shall see what we shall see.
Otherwise thought experiments may be interesting speculation but if they cannot be tested in any way they are utterly worthless. They may serve to amuse around the fire during dark winter nights as will a crossword or other logical game.
But whilst wasting time on such useless what might or might not be arguments may be diverting it is also utterly meaningless: as is the paper you have so carefully and precisely analysed.
That such balderdash can be written and is thought worthy of publication tells us much about the authors, the reviewers, the editors and their intellectual abilities and standards. It tells us nothing about the real world.
Kindest Regards
. . . a 100% increase in CO2 (2XCO2, causing less than 4 Watts per sq. meter), something that will not occur until late this century — if ever.
If ever? I hope soon to see a post explaining whether or not that “goal” is attainable. How fast can human activities inject CO2 into the atmosphere? The faster we try (demand for coal and oil) the more costly they will become. Higher prices reduce demand and encourage alternatives. Can coal and oil be supplied fast enough and consumed fast enough?
How long does CO2 stay in the atmosphere? Is it 5, 10, or 200 years? Unless this is known how can one proceed?
Maybe someone has looked into this issue and I’ve missed it. Still, it is nice to see that Dr. Roy entertains the thought.
Thanks for the insight into the cleverness of the paper. Appreciated.
“Specifically, they ran a climate model experiment in which they instantaneously removed all of the atmospheric greenhouse gases except water vapor, and they got rapid cooling “plunging the climate into an icebound Earth state”. ”
Do you think that their climate model might be wrong? If I got such an answer I would rebuild my model!
The earths’ atmosphere is the direct result of the ocean of water that covers 3/5 of the planets surface. The earths’ climate is regulated by the energy management of the charactoristics of water and the circulation of water in the oceanic basins. DUH!
These guys need to go back to grade school science and this time pay attention! pg
Easiest way to understand that CO2 isn’t the main driving:
The 30% increase in atmospheric CO2 over the last 150 or so years has resulted in very little change in temperature.
In a little more detail, if CO2 is the main driver and increased 30%, then either (a) the absorption bands near CO2 are completely saturated and/or (b) there are some extreme negative feedbacks.
Don’t warmists say that both of those claims are wrong?
-Scott
I don’t believe enough attention is paid to the absolute humidity. If there are an average of X tons of water vapor in the atmosphere and that increases to a global average of X+Y tons, then one would expect more “forcing” from an increase in CO2 but maybe that depends on where that increase in vapor occurs. An increase in absolute humidity at the poles in winter would have a much different impact that such an increase in the tropics.
Bothering me is this notion that increasing CO2 can cause an change in radiation into space when there is already so much water vapor that the atmosphere is practically opaque already in many places. It is like being in a enclosed room and then drawing a curtain across the closed door. The door already blocks all the light, drawing that curtain across it doesn’t block any more if it. Granted the poles are pretty dry and that is where the impact should be most felt if CO2 is the culprit.
By now we should be noticing measurably higher winter temperatures at the poles as heat is prevented from radiating into space over the winter by atmospheric CO2 that does not precipitate from the air. Are we noticing significantly higher winter temperatures at the South Pole station that track in increase with the atmospheric CO2 level? If there is anywhere on the planet that we should be able to directly measure the impact of CO2 it should be at the South Pole station. No land use changes there! Since there are quite a lot of data recorded at that station, it should be possible to trend the temperatures measured there against the CO2 levels. Though I would have to note that the 10,000 feet altitude of the station takes it above a lot of the atmosphere.
Speaking of 10,000 feet altitude, that is another thing I have often wondered about. During a glaciation, when one considers that a place like Chicago or Belingham, WA was covered with 5000 feet or more of ice, I would expect the altitude of the surface of the ice to have an impact on the weather there. For example, the thicker the ice gets and higher in altitude the surface gets, the colder the average temperature of that surface. The higher it gets, the colder it gets and more difficult it becomes to melt it.
Figuring 3.5 degrees for every thousand feet of altitude gained, the average annual temperature on the surface of a 5000 foot high ice plateau should be an annual temperature about 17.5 degrees colder than it would be at the surface level. The average annual temperature of Chicago is 49 degrees. This would take that down to 31.5 degrees. If there were 5000 feet of ice at Chicago today, it wouldn’t melt. The annual average temperature would be below freezing. You might get some surface melt in July when the average temperature would be 56 degrees or so but you would have only 5 out of 6 months with temperatures above freezing. Snow would accumulate in more months than it would melt. The monthly average temps are currently with 9 months above freezing and three months below.
Considering that at the South Pole station, they must continuously dig things out and raise them, it would seem that the surface at the station is continuing to rise. As it continues to rise, it will get even colder. It currently seems to be rising at about 6 feet per decade which means 60 feet in 100 years or 600 feet in 1000 years. That seems to me to be a pretty impressive accumulation rate!
Sorry to get off on a tangent but one thing leads to another.
The FUTILITY of Man-made Climate Control by limiting CO2 emissions
A Layman’s view: Just running the numbers: watch
On average world temperature is ~+15 deg C. This is sustained by the atmospheric Greenhouse Effect ~33 deg C. Without the Greenhouse Effect the planet would be un-inhabitable at ~-18 deg C. The Biosphere and Mankind need the Greenhouse Effect.
Just running the numbers by translating the agents causing the Greenhouse Effect into degrees centigrade:
• Greenhouse Effect = ~33.00 deg C
• Water Vapour accounts for about 95% of the Greenhouse Effect = ~ 31.35 deg C
• Other Greenhouse Gases GHGs account for 5% = ~1.65 deg C
• CO2 is 75% of the effect of all accounting for the enhanced effects of Methane, Nitrous Oxide and other GHGs = ~1.24 deg C
• Most CO2 in the atmosphere is natural, more than ~93%
• Man-made CO2 is less than 7% of total atmospheric CO2 = ~0.087 deg C
• the UK contribution to CO2 is 2% equals = 1.74 thousandths deg C
• the USA contribution to CO2 is ~20% equals = 17.6 thousandths deg C
So closing all the carbon economies of the Whole World could only ever achieve a virtually undetectable less than -0.09 deg C. How can the Green movement and their supporting politicians think that their remedial actions and draconian taxes are able to limit warming to only + 2.00 deg C?
So the probability is that any current global warming is not man-made and in any case such warming could be not be influenced by any remedial action taken by mankind however drastic.
As this is so, the prospect should be greeted with Unmitigated Joy:
• concern over CO2 as a man-made pollutant can be discounted.
• it is not necessary to damage the world’s economy to no purpose.
• if warming were happening, it would lead to a more benign and healthy climate for all mankind.
• any extra CO2 is already increasing the fertility and reducing water needs of all plant life and thus enhancing world food production.
• a warmer climate, within natural variation, would provide a future of greater opportunity and prosperity for human development. This has been well proven in the past and would now especially benefit the third world.
Nonetheless, this is not to say that the world should not be seeking more efficient ways of generating its energy, conserving its energy use and stopping damaging its environments. It remains absolutely clear that our planet is vastly damaged by many human activities such as:
• environmental pollution.
• over fishing.
• forest clearance.
• industrial farming.
• farming for bio-fuels .
• and other habitat destruction.
And there is a real need to wean the world off the continued use of fossil fuels simply on the grounds of:
• security of supply
• increasing scarcity
• rising costs
• their use as the feedstock for industry rather than simply burning them.
The French long-term energy strategy with its massive commitment to nuclear power is impressive, (85% of electricity generation). Even if one is concerned about CO2, Nuclear Energy pays off, French CO2 emissions / head are the lowest in the developed world.
However in the light of the state of the current solar cycle, it seems that there is a real prospect of damaging cooling occurring in the near future for several decades. And as power stations face closure the lights may well go out in the winter 2016 if not before.
All because CO2 based Catastrophic Man-made Global Warming has become a state sponsored religion.
And now after “Splattergate” thanks to the 10:10 organisation everyone now knows exactly how they think.
http://www.disinfo.com/2010/10/murdering-people-who-disagree-with-you/
Splattergate is classic NOBLE CAUSE CORRUPTION. It is probably the most egregious piece of publicity ever produced in the Man-made Global Warming cause. This short film shows doubting schoolchildren being blown up and having their entrails spread over their classmates because they may have been less than enthusiastic about the CAUSE.
So any misrepresentation is valid in the Cause and any opposition however cogent or well qualified is routinely denigrated, publically ridiculed and as we now see literally terminated.
Do those clowns ever bother to look at the geological record? According to their reasoning the Carboniferous period ( Pennsylvanian and Mississipian for our American friends), a period where dragonfly wings reached spans of uo to 2 metres because of higher atmospheric density due to high carbon dioxide levels, should have been a period of runaway greenhouse warming. Maybe dragonfly wings were coated with fire retardant in those times?
Dr. Spencer,
Your post was valuable in showing the logical structure of the paper by Lacis, Schmidt, Rind, and Ruedy.
Thank you for posting at WUWT.
John
As I understand it, the greenhouse warming theory was developed at a time when the structure of the atmosphere was assumed to be the same as it is at ground level all the way to outer space. That theory, even today, does not appear explain why our atmosphere should be composed of various distinct levels such as the troposphere, stratosphere, mesosphere, and so on.
It seems obvious to me that the tropopause must be that region in the atmosphere where thermal energy convected upward by our active weather systems must escape to outer space. As I now understand it, radiation from H2O molecules at that level, either as monomolecular H2O vibration states, vibration states of H2O molecular-aggregates, or the 5.13 micron (my estimate) photons from H2O intermolecular hydrogen bond formation, are the primary mechanisms available for cooling the tropopause to a nominal temperature of minus sixty degrees C. so that life is possible on the surface.
So far, I have only seen CO2 absorption plus H2O absorption at the surface used as an indicator for the greenhouse effect. It seems to me, however, that the ability, if any, of CO2 to interfere with H2O radiation to outer space from the level of the tropopause should be the primary problem posed by increasing CO2 in the atmosphere. I note that CO2 is relatively transparent at 5.13 microns.
Of course, direct radiation from the surface also helps, but I doubt if any model is going to be realistic if it does not include the effect of H2O tropopause cooling.
Ref:
“How Greenhouse Gases Work”
Robert Clemenzi, 2009
http://mc-computing.com/qs/Global_Warming/EPA_Comments/TheGreenhouseEffect.doc
I think the papers flaws are far more obvious than you give them. Firstly I don’t think anyone will take a paper based on a climate model seriously, because if the model isnt perfect in the first place, the rest is wasted ink, and NO-ONE thinks they are perfect!
Man creates model, ignores all natural climate drivers, increases co2, adds in over the top feedbacks all driven by co2 to force fit model to temp record. As no natural drivers are there and only the co2 forcing changes, and as this triggers “Feedbacks” they will of course show that co2 is the big driver, that because in their models its the ONLY driver!
Its obvious circular reasoning combined with blatant ignorance. There models assume the climate was a flat line pre-1850 and I seriously doubt that. My BS monitor went off the second I saw the abstract and I didn’t need to read any further, I had already figured out their circular reasoning with even reading on! Its just a travesty they can not see it themselves and tax payer money gets wasted on pointless work like this. However, its too tempting for scientists to knock out a quick headline grabbing paper than doing real experiments or carrying out years of careful observation – or even testing / calibrating their models correctly.
Ot but this warmist site at least is honest. Temp UHA graph shows NO significant warming at all
http://chartsgraphs.wordpress.com/2010/08/19/enhanced-uah-channel-5-temperature-anomaly-trend-chart/
As a geologist and a scientist, I am well aware now easily I can BS those who are not scientists. This paper is a classic example of the expression “BS baffles brains”.
Many scientists have the opportunity to BS the general public, but the vast majority of those, like myself, choose not to, because of: i) obvious ethical considerations, and/or ii) fear of being publicly exposed by one’s peers for practicing deceit and/or bad science. The latter is the reason why we have professional scientific bodies. On the whole, this type of self-policing works well. It fails however, when the Establishment of that body has one belief (sometimes politically motivated as in the case of ‘climate change’) and refuses to consider or tolerate any dissent.
Climate ‘science’ is different to real science in that the danger of being exposed by dissenting peers is very small, as the government funded Establishments have rigorously filtered out all those who dared challenge the dubious theories of the status quo.
There are a few notable exceptions to the above, but not enough to make an impact on the general public or goofy politicians. So the world has to be saved from the foolishness, fraud and deceit of climate ‘scientists’ by the blogosphere – it is scary to think 20 years ago, they would have got away with it and the world might have embarked on a series of catastrophic economic programs, which would have had an almost indiscernible impact on atmospheric CO2 levels. We are still in danger of this happening today, but it is now becoming increasingly less likely as a result of the continued and steady increase of scepticism in the minds of the general public.
Hmmm, a simple calculation. The sun delivers 340 watts/sqM at the top of the atmosphere. Of this about 100 watts/sqM is reflected back out to space mainly by clouds. Now if there were no green house gases at all (including water vapour) there would also be no clouds. At 340 watts/sqM of insolation according to Stefans law the average temperature would be 5C or about 9C colder than it is now.
So if we say all green house effect is due to CO2 then the 30 watts/sqM contributed by CO2 at present yields 9C of warming. Thus the additional 4 watts/sqM caused by doubling CO2 should contribute a further 4 * 9/30 = 1.2C. Not exactly the 3C + that is claimed. Of course they do say water has some effect on temperature so either they are saying water vapour causes warming in which case the contribution from CO2 is even less than calculated or they have to say water vapour causes cooling in which case increasing it will further cool the Earth not warm it. As I said Hmmmm.
More to the point, water vapour contributes warming through the green house effect and cooling through clouds reflecting energy back out to space. But cloud cooling is roughly linear with cloud mass whereas green house warming is logarithmic. This means at very low concentrations the green house warming dominates but as the concentration rises the incremental warming effect diminishes while the cloud cooling continues to rise strongly and will start to dominate. The combination of these two result in the establishment of a stable operating point for the climate maintained by negative water vapour+ cloud feedback.
Remember the claim is that as temperatures rise more water evaporates which increases the green house contribution from water vapour. But unless all the oceans end up in the sky, more evaporation must also mean more precipitation and rain only comes from low clouds. So more precipitation means more low cloud mass and low clouds are known to cause cooling.
Andy Lacis commented on Roy’s original post over at drroyspencer.com.
http://www.drroyspencer.com/2010/10/does-co2-drive-the-earths-climate-system-comments-on-the-latest-nasa-giss-paper/#comment-3411
What confuses me is that an article that merely explores the GISS model and doesn’t really come up with any new, exciting research results gets published in Science. I’ll be lucky if I ever get anything published in Science in my career.
Specifically, they ran a climate model experiment in which they instantaneously removed all of the atmospheric greenhouse gases except water vapor, and they got rapid cooling
huh?
This is perhaps the most idiotic thought experiment ever devised.
What happens when you remove all green house gases except CO2?
Well the atmosphere shrinks to be about a foot thick then the CO2 freezes solid and you have no atmosphere.
Anyway my cartoon description is not actually true still when CO2 is a micro gas and all other gases removed from it presence the earth would be a very very very very cold world.
This fact makes me wonder why Roy wrote this:
But unless one is very careful in reading this paper and knows exactly what the authors are talking about, it is easy to get distracted by superfluous details and miss the main point.
Careful? why…their thought experiment is pure stupidity.
I really don’t understand the argument that water vapour reacting quickly to temperature change makes it a feedback, surely that is a relation of changing phase at tropospheric temperatures and there being a limitless supply of the liquid stuff. Any one know what happens when the sun is removed from the model 😉 (that varies a lot during the course of the day too.. though obviously not a feedback)
Dr. Pielke Sr. has also commented on the Lacis et al. paper at http://pielkeclimatesci.wordpress.com/2010/10/15/comment-on-the-science-paper-atmospheric-co2-principal-control-knob-governing-earth%E2%80%99s-temperature-by-lacis-et-al-2010/
Does the paper explain the dynamics of the model without any water vapour as that in itself seems to be an interesting thought experiment. Without water in the system we don’t really have any weather systems though I don’t think it is intuitively obvious how the atmosphere behaves, somewhat like Mars I’d guess.
Speaking as a layman, I don’t understand the difference between climate ‘forcing’ and climate ‘feedback’ — it seems a matter of semantics.
The Sun’s radiation is surely the only climate forcing agent.
When you look at their professional histories, it’s apparent that the instigators of the CAGW frenzy and their disciples have stared out with the firm conviction that human CO2 emissions were a grave threat and have set about to prove it by fair means or foul.
They are trapped on a faulty logic treadmill
http://hollywoodinhidef.com/wp-content/uploads/EscherStairs.jpg.
It seems to me that the problem with the AGW hypothesis is not one of faulty science so much as faulty reasoning.