NEW 4/10/09: There is an update to this post, see below the “read the rest of this entry” – Anthony
Guest Post by Richard Lindzen, PhD.
Alfred P. Sloan Professor of Meteorology, Department of Earth, Atmospheric and Planetary Science, MIT
This essay is from an email list that I subscribe to. Dr. Lindzen has sent this along as an addendum to his address made at ICCC 2009 in New York City. I present it here for consideration. – Anthony
Simplified Greenhouse Theory
The wavelength of visible light corresponds to the temperature of the sun’s surface (ca 6000oK). The wavelength of the heat radiation corresponds to the temperature of the earth’s atmosphere at the level from which the radiation is emitted (ca 255oK). When the earth is in equilibrium with the sun, the absorbed visible light is balanced by the emitted heat radiation.
The basic idea is that the atmosphere is roughly transparent to visible light, but, due to the presence of greenhouse substances like water vapor, clouds, and (to a much lesser extent) CO2 (which all absorb heat radiation, and hence inhibit the cooling emission), the earth is warmer than it would be in the absence of such gases.
The Perturbed Greenhouse
If one adds greenhouse gases to the atmosphere, one is adding to the ‘blanket’ that is inhibiting the emission of heat radiation (also commonly referred to as infrared radiation or long wave radiation). This causes the temperature of the earth to increase until equilibrium with the sun is reestablished.
For example, if one simply doubles the amount of CO2 in the atmosphere, the temperature increase is about 1°C.
If, however, water vapor and clouds respond to the increase in temperature in such a manner as to further enhance the ‘blanketing,’ then we have what is called a positive feedback, and the temperature needed to reestablish equilibrium will be increased. In the climate GCMs (General Circulation Models) referred to by the IPCC (the UN’s Intergovernmental Panel on Climate Change), this new temperature ranges from roughly 1.5°C to 5°C.
The equilibrium response to a doubling of CO2 (including the effects of feedbacks) is commonly referred to as the climate sensitivity.
Two Important Points
1. Equilibration takes time.
2. The feedbacks are responses to temperature – not to CO2 increases per se.
The time it takes depends primarily on the climate sensitivity, and the rapidity with which heat is transported down into the ocean. Both higher sensitivity and more rapid mixing lead to longer times. For the models referred to by the IPCC, this time is on the order of decades.
This all leads to a crucial observational test of feedbacks!
The Test: Preliminaries
Note that, in addition to any long term trends that may be present, temperature fluctuates on shorter time scales ranging from years to decades.
Such fluctuations are associated with the internal dynamics of the ocean- atmosphere system. Examples include the El Nino – Southern Oscillation, the Pacific Decadal Oscillation, etc.
These fluctuations must excite the feedback mechanisms that we have just described.
The Test
1. Run the models with the observed sea surface temperatures as boundary conditions.
2. Use the models to calculate the heat radiation emitted to space.
3. Use satellites to measure the heat radiation actually emitted by the earth.
When temperature fluctuations lead to warmer temperatures, emitted heat radiation should increase, but positive feedbacks should inhibit these emissions by virtue of the enhanced ‘blanketing.’ Given the model climate sensitivities, this ‘blanketing’ should typically reduce the emissions by a factor of about 2 or 3 from what one would see in the absence of feedbacks. If the satellite data confirms the calculated emissions, then this would constitute solid evidence that the model feedbacks are correct.
The Results of an Inadvertent Test
Above graph:
Comparison of the observed broadband LW and SW flux anomalies for the tropics with climate model simulations using observed SST records. The models are not given volcanic aerosols, so the should not expected to show the Mt. Pinatubo eruption effects in mid-1991 through mid-1993. The dashed line shows the mean of all five models, and the gray band shows the total rnage of model anomalies (maximum to minimum).
It is the topmost panel for long wave (LW) emission that we want.
Let us examine the top figure a bit more closely.
From 1985 until 1989 the models and observations are more or less the same – they have, in fact, been tuned to be so. However, with the warming after 1989, the observations characteristically exceed 7 times the model values. Recall that if the observations were only 2-3 times what the models produce, it would correspond to no feedback. What we see is much more than this – implying strong negative feedback. Note that the ups and downs of both the observations and the model (forced by observed sea surface temperature) follow the ups and downs of temperature (not shown).
Note that these results were sufficiently surprising that they were confirmed by at least 4 other groups:
Chen, J., B.E. Carlson, and A.D. Del Genio, 2002: Evidence for strengthening of the tropical general circulation in the 1990s. Science, 295, 838-841.
Cess, R.D. and P.M. Udelhofen, 2003: Climate change during 1985–1999: Cloud interactions determined from satellite measurements. Geophys. Res. Ltrs., 30, No. 1, 1019, doi:10.1029/2002GL016128.
Hatzidimitriou, D., I. Vardavas, K. G. Pavlakis, N. Hatzianastassiou, C. Matsoukas, and E. Drakakis (2004) On the decadal increase in the tropical mean outgoing longwave radiation for the period 1984–2000. Atmos. Chem. Phys., 4, 1419–1425.
Clement, A.C. and B. Soden (2005) The sensitivity of the tropical-mean radiation budget. J. Clim., 18, 3189-3203.
The preceding authors did not dwell on the profound implications of these results – they had not intended a test of model feedbacks! Rather, they mostly emphasized that the differences had to arise from cloud behavior (a well acknowledged weakness of current models). However, as noted by Chou and Lindzen (2005, Comments on “Examination of the Decadal Tropical Mean ERBS Nonscanner Radiation Data for the Iris Hypothesis”, J. Climate, 18, 2123-2127), the results imply a strong negative feedback regardless of what one attributes this to.
The Bottom Line
The earth’s climate (in contrast to the climate in current climate GCMs) is dominated by a strong net negative feedback. Climate sensitivity is on the order of 0.3°C, and such warming as may arise from increasing greenhouse gases will be indistinguishable from the fluctuations in climate that occur naturally from processes internal to the climate system itself.
An aside on Feedbacks
Here is an easily appreciated example of positive and negative feedback. In your car, the gas and brake pedals act as negative feedbacks to reduce speed when you are going too fast and increase it when you are going too slow. If someone were to reverse the position of the pedals without informing you, then they would act as positive feedbacks: increasing your speed when you are going too fast, and slowing you down when you are going too slow.
Alarming climate predictions depend critically on the fact that models have large positive feedbacks. The crucial question is whether nature actually behaves this way? The answer, as we have just seen, is unambiguously no.
UPDATE: There are some suggestions (in comments) that the graph has issues of orbital decay affecting the nonscanner instrument’s field of view. I’ve sent a request off to Dr. Lindzen for clarification. – Anthony
UPDATE2: While I have not yet heard from Dr. Lindzen (it has only been 3 hours as of this writing) commenter “wmanny” found this below, apparently written by Lindzen to address the issue:
“Recently, Wong et al (Wong, Wielicki et al, 2006, Reexamination of the Observed Decadal Variability of the Earth Radiation Budget Using Altitude-Corrected ERBE/ERBS Nonscanner WFOV Data, J. Clim., 19, 4028-4040) have reassessed their data to reduce the magnitude of the anomaly, but the remaining anomaly still represents a substantial negative feedback, and there is reason to question the new adjustments.”
I found the text above to match “wmanny’s” comment in a presentation given by Lindzen to Colgate University on 7/11/2008 which you can see here as a PDF:
http://portaldata.colgate.edu/imagegallerywww/3503/ImageGallery/LindzenLectureBeyondModels.pdf
– Anthony
UPDATE3: I received this email today (4/10) from Dr. Lindzen. My sincere thanks for his response.
Dear Anthony,
The paper was sent out for comments, and the comments (even those from “realclimate”) are appreciated. In fact, the reduction of the difference in OLR between the 80’s and 90’s due to orbital decay seems to me to be largely correct. However, the reduction in Wong, Wielicki et al (2006) of the difference in the spikes of OLR between observations and models cannot be attributed to orbital decay, and seem to me to be questionable. Nevertheless, the differences that remain still imply negative feedbacks. We are proceeding to redo the analysis of satellite data in order to better understand what went into these analyses. The matter of net differences between the 80’s and 90’s is an interesting question. Given enough time, the radiative balance is reestablished and the anomalies can be wiped out. The time it takes for this to happen depends on climate sensitivity with adjustments occurring more rapidly when sensitivity is less. However, for the spikes, the time scales are short enough to preclude adjustment except for very low sensitivity.
That said, it has become standard in climate science that data in contradiction to alarmism is inevitably ‘corrected’ to bring it closer to alarming models. None of us would argue that this data is perfect, and the corrections are often plausible. What is implausible is that the ‘corrections’ should always bring the data closer to models.
Best wishes,
Dick
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I would suggest that some effort should be given to attacking this issue sideways. Perhaps we can gain clarity with questions-
When was the debate over? (this would actually provide some useful information as to the amount of scientific evidence necessary to close debate- surely we have a right to a date. I’m really surprised noone has asked this question)
Look for what is not there. We are told that we have passed a tipping point and due to the CO2 already in the pipeline we can expect some level of climate disruptions. One would expect therefore to find massive infrastructure projects in the trillion dollar budget passed by Congress to combat rising sea levels, droughts, floods etc. Where are they?-Show the sea wall projects etc. Sometimes questions are as powerful as facts.
Hence the “Gore Effect”!
To Wayne (09:48:00) :
You said: “according to your first sentence, there is NO radiative heat transfer mechanism.”
Actually, my first sentence: “Infrared is not heat radiation” does not equal “there is no radiative heat transfer mechanism”.
To rephrase, electromagnetic energy and heat energy are profoundly different forms of energy. Electromagnetic energy radiates; heat does not. That does not mean there is no radiative heat transfer mechanism–of course there is.
A warm body loses heat by radiating electromagnetic energy in infrared or some other wavelength spectrum. That EM energy MAY be absorbed by another body and cause an increase in heat in that body.
For many purposes, it is convenient to treat IR and heat as equivalent, but ignoring the fundamental physical difference between the two forms of energy can lead to muddy thinking and silly hypotheses like the Invisible Global Heat Sink.
Wayne, I suspected no one would read my whole post and understand it, especially since it was hastily written and mostly off topic. You prove me right. I’m probably a little old to go back to grad school, especially to study freshman physics. And you’re not everyone else.
LOL
George E. Smith (11:25:30) :
You’re right; I was being pedantic. I thoroughly enjoyed Prof. Lindzen’s essay. I certainly have a better understanding of his topic (of which my post was somewhat off-), and I understand why he used the equivalence language.
It just makes me crazy to channel surf through the Discovery Channel, and see a nice, neat, and convincing animation showing “heat” radiating off the surface of the earth, and being trapped by an (exclusively anthropogenic) insulating blanket of carbon dioxide. I much prefer the Discovery Channel’s work with “Dirty Jobs”.
And it really upsets me when scientifically literate folks use the equivalence language to convince themselves of things that can’t possibly be so in the real world.
“Heat is not a noun”. I’ll have to remember that.
This may be a boring question for you here, but what study or science is the foundation of this belief that doubling the CO2 in the atmosphere raises temperature about one degree? The IPCC report is vague about this. Thanks for any pointers you all can give me.
Just this AM I had a conversation with one of the alarmists, nowhere near a scientist or engineer type. More of just a wide eyed arm waver. After he waved his arms around for a while, I injected a single question “How much CO2 is too much” — He answered enthusiastically “none”.
At which I added, ‘do you know what that would mean?’ — Blank stare.
kevin: the 255 K is calculated from the average Top of Atmosphere outward radiation (which equals radiation in), assuming blackbody emissions (T = (Radiation/alpha)^0.25. It is supposedly the temperature the earth’s surface would be without greenhouse gases. But it is a baloney number, because it represents only a planet, like the moon, that has no atmosphere or water. Of course, the Earth has both, so the calculation is complete nonsense. In fact, correct calculations that include the effects of the atmosphere and water would show that the Earth’s average temperature “should” be what it is, about 15 C. The “greenhouse gases” simply help transfer kinetic energy (temperature) to the N2 and O2 that makes up 98% of the atmosphere, through the process of thermalization. Convection makes sure that the greenhouse gases (CO2, HOH, etc.) cannot cause further warming. Indeed, if they did cause some “blanket” warming effect, then it would have to be hotter in your favorite tropical paradise on a clear day than it is in Phoenix in July. But it never is.
Here’s an article that possibly explains the mechanisms: http://www.ilovemycarbondioxide.com/pdf/Rethinking_the_greenhouse_effect.pdf
pmoffitt wrote:
“We need a new strategy to present the facts.”
It would be very helpful, I think, if someone with a good handle on this issue could formulate bettable questions that would be easy for the predictions-betting website Intrade to settle, and challenged alarmists to put their money where their mouth is wrt the various indicators of global warming, such as arctic ice extent, sea level, heating degree days in the US, ocean temperatures, and one or two other matters. (There should be several questions because none of these indicators correlates perfectly with the global temperature, so people will need to spread their bets.)
I described what might be done in detail (using the Dublin-based event-prediction betting site Intrade) about 25% of the way through this thread on this site:
http://www.google.com/url?sa=U&start=2&q=http://wattsupwiththat.com/2009/03/02/poll-and-polar-ice-trends/&ei=bX3SSfmbIZG4sgPsmKjGAw&sig2=dlVs9GDVE1GqULp68toGCg&usg=AFQjCNFAxQsx5StKiAAJ0pksVzbmZVDLrA
2. The feedbacks are responses to temperature – not to CO2 increases per se.
After 2002 the temperatures have been going down supposedly due to decreased activity of the Sun even though CO2-levels have risen. Because the impacts of the feedbacks are functions of the temperature, they must be smaller now. So, there is no heat hiding in the oceans or elsewhere that would start a rapid runaway heatwave after the activity of the Sun has returned to previous levels.
Mike Ramsey (06:02:21) wrote:
Roger Knights (05:29:30) :
“Excellent, first class. A calm look at reality is what is always needed.”
But it hasn’t been peer-reviewed, nyah, nyah!
“Note that these results were sufficiently surprising that they were confirmed by at least 4 other groups:”
Including a bibliography doesn’t make a paper peer-reviewed. This paper was presented at ICCC and e-mailed to Anthony–that’s all, so far. (AFAIK)
Mike Ramsey continued:
Not sure what your point was.”
I was parodying a typical Insister response to Lindzen. I could have included “/sarc]” at the end, but that sort of nudge in the ribs spoils the joke.
Graeme Rodaughan (03:00:10) :
Ha Ha…. Australia will Rule the next (Frozen) Millenium (Post 3000 AD). Just take my word for it……
And who are you going to play cricket against? No more fast, dry pitches, that’s for sure!
Either Richard Lindzen and pretty much everyone else who has looked at this data is totally wrong or the idea of a large positive feedback, in fact any positive feedback is dead.
Chris V. “If clouds are a negative feedback (as Lindzen implies in the opening post) then the cloud feedback would “resist” the ice ages- not help them along.”
This is shallow thinking. You forget that Milankovitch forcing is heterogeneous. The net change in radiation is tiny, making Ice Ages seemingly impossible even in the positive feedback paradigm. The reason that they are possible is because the Milankovitch forcing alters horizontal heat fluxes. When something strongly resists changes in tropical temperature (a negative feedback)-you will get mean temperature changes. At the poles, the ice albedo feedback helps to. Cheers.
Chris V. (09:22:48) :
In the context of ice ages, albedo is mainly a function of the extent of ice cover, and it is a POSITIVE feedback, not negative.
Warming results in less ice cover; less ice cover means lower albedo; lower albedo means more sunlight is absorbed, which translates into more warming.
Which in turn increases humidity in the atmosphere, which leads to more clouds and precipitation, which cools things down again.
Our planet’s temperature is controlled by water in solid, liquid and gaseous form.
To Jae,
Thank you! I was thinking the same thing, but was uncomfortable expressing it on a scientific blog without the data to back it up. (have pity on me. I’m an engineer turned salesman). I’m looking forward to reading the pdf you’ve linked, which I’ll do now.
See this paper which deals with what I said above:
http://eaps.mit.edu/faculty/lindzen/171nocephf.pdf
Roger Knights on forming bettable questions-
I would submit all the claims of future climate are the equivalent of bets- bets are just a risk analysis of sorts. Congress with the recent budget has shown it does not believe its own global warming rhetoric in that the projects necessary to harden our infrastructure against the ravages of global warming etc are absent. Congress did not take the bet and from their recent actions they assume money has little value- which makes not taking the bet more surprising-it is not their money after all.
Gore made a bet that seas will not rise with his recent purchase in SF. (He also made a bet that the tectonic plate his property is sitting on in SF that is “moving” (undifferentiated slip) ten times faster than the sea is supposed to rise is also unimportant.)
One of my great concerns with the CO2 link to climate is the position being sold to the public that if we control CO2 we are free of climate anomalies and “freak” weather events. Control CO2 and climate does not change. This is a very dangerous if not criminal message. There are very good reasons to be hardening our infrastructure having nothing to do with CO2 but it is being held hostage because taking what might be seen as remedial action lessens the perception of crisis needed to press the larger global warming message.
Chris V:
Have you not considered that clouds may be a negative feedback acting against temperature increases, but not temperature decreases?
Given that one of the major effects of clouds is to increase the earth’s albedo, this seems like a reasonable proposition.
Also, it depends where the clouds are – equatorial clouds have a greater effect on the albedo than polar clouds, similarly clouds over the ocean and clouds during the daytime.
Anthony,
I have a (friendlier) response here
http://chriscolose.wordpress.com/2009/03/31/lindzen-on-climate-feedback/
I hope you can make an update accordingly.
The most dizzy aspect of this has been the ease at which alarmists have produced new observations which they attribute to AGW without
evidence of causation or correlation.
And while they claim, or suggest, these many outcomes are, or may be, a result of human global warming they continue to denigrate skeptics for not having peer reviewed science to support all of their opposing science and counter claims.
Here in Oregon the left and media add daily to the supposed AGW caused harm. Everything they look at they see AGW effect and it gets printed.
While never looking back to the mounting flaws in AGW.
Like many other locales, of course.
Is this an adequate summary?
The IPCC climate models that have now lost most of their reliability.
The Hockey Stick theory relied upon false assumptions that the Medieval Warm period and mini-ice age were regional events and not global climate. Among other flaws.
The IPCC had falsely discounted the impact of urbanization on temperature readings.
Experts have now recognized an effect potentially equal to the entire warming the IPCC had earlier attributed to CO2 emissions.
Along with the Urban Heat Island effect, mis-location of sensor equipment and 70% of rural sensors stations taken off line, it is entirely possible that all or most of the warming attributed to CO2 emissions could be from poor temperature measuring.
AGW whoppers include using weather observations as evidence of AGW. The very thing they disparage skeptics for doing.
The blatantly false connection of AGW to Hurricane Katrina.
Baseless suggestions that heat waves and wildfires are evidence of AGW.
Sea ice fluctuation attributed to AGW without any a validated scientific connection.
California Wildfires blamed on AGW while half were arson.
Similar misrepresentation of Australian fires.
Ocean dead zones have been connected to AGW with no more than a description of a possible connection.
The OSU professor who supposed that connection is now the head of NOAA.
Snow pack reduction is not happening as projected and has never been shown to be AGW related.
Ocean levels are not rising as projected and nothing but assumptions ever connected sea rise to AGW.
Lack of projected symmetry in NH and SH polar cap warming.
Symmetry in NH & SH CO2 increases contradict IPCC theories.
The entirely contrived observation of AGW threatening polar bear populations.
Best estimates show a mere 1 degree F of natural and historically typical global temperature increase over the past 100 years, yet we are believe that all these observations, without any supporting science, are already resulting from the 1 degree and human CO2 emissions?
The craziness of the AGW campaign now trots out predictions of famine, drought, wars, 100’s of millions of climate refugees, agriculture collapse, ocean death, deforestation, and massive heat death and disease. All of which has grown out of faulty IPCC climate models and hypothetical assumptions that never seems to waiver in the face of extensive refutation.
I just don’t think this looks like a “scientific” debate.
tarpon (12:31:11) :
A very Karl Popper question. I start all discussions on the AGW subject with the following question: What information- if it existed -would prove your position on AGW false. If the answer is there is none- there is no reason to continue the conversation. Science must be falsifiable.
In regards to the need for questions- NASA/IPCC should provide the “falsifiable ” information to prove the models wrong. Without an agreed false position no argument carries weight.
Perhaps we should pass a law that states no funding shall be allowed for any scientific research relating to a new crisis unless the falsifiable positions are first posited. The global warming impasse is the result on no agreement as to information that can prove the theory false.
“I dont understand how i can look at a theory and come to the exact opposite conclusions of the person who proposed it”
Because for the person who proposed it (Lovelock) Gaia has become an animate object, rather than a feedback mechanism. He now sees Gaia as taking revenge on the inhabitants (us) for our nasty habits. Everything will be better when our numbers are reduced, which may be true, but it won’t be CO2 that does it.
Dougal Dixon’s arresting book ‘After Man’ suggests that our extinction will be the result of over-exploitation of resources, but goes on to postulate an evolutionary explosion in our absence, in what looks like an unaffected climate!
James P-anyone who speculates about the future has to leave the climate apocalypse out because if it really happened, there wouldn’t be much to speculate about. This probably is a major reason that a futurist like Dyson can’t support it-his vision of an ever advancing human race in which technology emerges to meet any challenge is diametrically opposed to the idea of an insurmountable obstacle like a “climate crisis”. Well, that, and its bunk.
[snip – you have posted under several names and do not provide a valid email address, a valid email address is required to post here]
James P (13:39:45) :
Science requires testable assumptions- Lovelock’s Gaia is philosophical at best (no offense meant to those philosophers heavy on the math) The deep sea vent communities would seem to challenge the single Gaia theory- but again with out a falsifiable place to start we are forced to argue with ourselves. “Black swans” are required.