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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Good article, but it’s too bad that Lindzen falls for the “blanket” baloney. If that idea is true, it would have to be hotter in Miami on a clear summer day than in Phoenix. The reverse is true.
anna v (08:41:15) :
“So of course there are negative feedbacks. The most important one iw albedo changes.”
I think albedo changes are positive feedback (I’m thinking of melting ice that is). Melting ice is a positive feedback change, the effect of which gets smaller as the ice shrinks to only be at the poles. This ‘should’ show up as temperature changes slowing down as the earth comes out of a ice age … but I don’t see it.
Going from these types of positive feedbacks to negative feedbacks ‘should’ result in a curved top. Delayed negative feedback ‘should’ result in overshoot and oscillations (on the flat part).
Is it possible that positive feedback switches to negative feedback so suddenly to accomplish the discontinous temperature change? Sure, its ‘possible’, but it is certainly not the simplest theory. Why not consider the much simpler theory of reaching the a physical limit. That seems to match well with the data and doesn’t require any ‘hand waving’ at complexities.
From vg quoting the Examiner quoting Hansen:
“…the mistaken impression that concern about global warming is based on climate models, which in reality play little role in our understanding…”
Actually, I think it’s possible Dr. Hansen actually believes this.
To Ed Fix:
according to your first sentence, there is NO radiative heat transfer mechanism. And there is NO infrared or near infrared imaging technique or terminology.
I don’t know who need to go back to graduate school to study radiative transfer course, Ed Fix or everyone else.
LOL
Richard Heg (23:48:31) :
“One thing that puzzles me in the environmental movement with regard to feedback is Gaia theory as proposed by James Lovelock which as defined in wiki http://en.wikipedia.org/wiki/Gaia_theory says:
“The Gaia hypothesis is an ecological hypothesis proposing that the biosphere and the physical components of the Earth (atmosphere, cryosphere, hydrosphere and lithosphere) are closely integrated to form a complex interacting system that maintains the climatic and biogeochemical conditions on Earth in a preferred homeostasis.”
This sounds quite elegant to me, that the biological and geological activity produce a feedback system which unlike our neighbors Mars and Venus has kept the earth in a state which allows life to exist. It goes on to say:
“Some relatively simple homeostatic mechanisms are generally accepted. For example, when atmospheric carbon dioxide levels rise, the biomass of photosynthetic organisms increases and thus removes more carbon dioxide from the atmosphere, but the extent to which these mechanisms stabilize and modify the Earth’s overall climate are not yet known.”
So my reading of Gaia theory says nothing to worry about the earth is full of feedbacks which keep thing relativelyly stable. Problem solved, now lets have a nice cup of tea.
However James Lovelock seems to have a different vision, he seems to see humans as a cancer. Here is a quote from a recent interview:
“Because of this (AGW), the cull during this century is going to be huge, up to 90 per cent. The number of people remaining at the end of the century will probably be a billion or less.”
http://www.newscientist.com/article/mg20126921.500-one-last-chance-to-save-mankind.html
I dont understand how i can look at a theory and come to the exact opposite conclusions of the person who proposed it”.
Richard,
It’s because you look at things from a scientific point of view.
The other party looks at it from a political ( eco fascist ) view.
http://green-agenda.com and Chapter 21 http://www.un.org/esa/sustdev/documents/agenda21/index.htm
An accelerator pedal has negative feedback, because pressing it causes the car and pedal to move away from your foot and decreases the pressure on the pedal. A brake pedal has positive feedback, because pressing it causes the car and pedal to slow more quickly than your foot so the foot tends to push on it harder.
Ron de Haan: Some people think that feedbacks keep the Earth in some ideal state of balance, and humans have upset the balance. Others think that feedbacks tend to encourage the Earth toward being habitable but the system is both chaotic and open to outside influences so there is no guaranteed balance nor comfortable range.
Unresolved issues: The Little Ice Age affected many regions recently. Were those temperatures at the proper balance point? Which of the recent temperatures is the proper temperature for the Earth? Is the proper temperature reached during a glacial event?
There is an excellent article in Wired (March 3, 2009), “Recipe for Disaster: The Formula That Killed Wall Street.”
http://www.wired.com/techbiz/it/magazine/17-03/wp_quant?currentPage=1
This article analyzes how David X Li’s work caused the worst economic meltdown since the Great Depression. Its opening paragraphs set the stage:
“A year ago, it was hardly unthinkable that a math wizard like David X. Li might someday earn a Nobel Prize. After all, financial economists—even Wall Street quants—have received the Nobel in economics before, and Li’s work on measuring risk has had more impact, more quickly, than previous Nobel Prize-winning contributions to the field. Today, though, as dazed bankers, politicians, regulators, and investors survey the wreckage of the biggest financial meltdown since the Great Depression, Li is probably thankful he still has a job in finance at all. Not that his achievement should be dismissed. He took a notoriously tough nut—determining correlation, or how seemingly disparate events are related—and cracked it wide open with a simple and elegant mathematical formula, one that would become ubiquitous in finance worldwide.”
“For five years, Li’s formula, known as a Gaussian copula function, looked like an unambiguously positive breakthrough, a piece of financial technology that allowed hugely complex risks to be modeled with more ease and accuracy than ever before. With his brilliant spark of mathematical legerdemain, Li made it possible for traders to sell vast quantities of new securities, expanding financial markets to unimaginable levels.”
“His method was adopted by everybody from bond investors and Wall Street banks to ratings agencies and regulators. And it became so deeply entrenched—and was making people so much money—that warnings about its limitations were largely ignored.”
“Then the model fell apart. Cracks started appearing early on, when financial markets began behaving in ways that users of Li’s formula hadn’t expected. The cracks became full-fledged canyons in 2008—when ruptures in the financial system’s foundation swallowed up trillions of dollars and put the survival of the global banking system in serious peril.”
There are significant similarities between Li’s work and the GCMs that the AGWers, media and policy makers ignore at their peril. If they get their, trillions of dollars will be squandered and our economy destroyed.
The closing paragraphs from this article put all modelers, especially climate modelers, and their work in perspective:
“Li has been notably absent from the current debate over the causes of the crash. In fact, he is no longer even in the US. Last year, he moved to Beijing to head up the risk-management department of China International Capital Corporation. In a recent conversation, he seemed reluctant to discuss his paper and said he couldn’t talk without permission from the PR department. In response to a subsequent request, CICC’s press office sent an email saying that Li was no longer doing the kind of work he did in his previous job and, therefore, would not be speaking to the media.”
“In the world of finance, too many quants see only the numbers before them and forget about the concrete reality the figures are supposed to represent. They think they can model just a few years’ worth of data and come up with probabilities for things that may happen only once every 10,000 years. Then people invest on the basis of those probabilities, without stopping to wonder whether the numbers make any sense at all.”
Chris V. (09:22:48) :
Ian Schumacher (09:38:23) :
Seems to me both of you should play with the toy modelthat shows how sensitive the earth temperature is to albedo, both positive and negative.
Has none of you looked up and seen clouds? Or do you think all that ice during ice ages came by magic?
In my opinion it is the large sun cycles that explain the ice ages, the feedback mechanisms are all those oscillations, both on the inclines and on the flat tops.
Just to say thanks realitycheck for answering my question re the Eocene!
I am not optimistic any fact is capable of pushing aside an endorsed government/ NGO paradigm. A greater understanding is required of the first model used to declare a crisis during the “Acid Rain Debate”-called the Magic Model (perhaps because it could magically produce whatever result one wanted). The scientific facts regarding soil acidifcation clearly showed acid rain was not a dominant factor in soil or water acidification however Congress passed the related legislation without having read the report. (EPA refused to release it till after the legislation was passed). The lead researcher, Ed Krug, was smeared by both EPA and the NGOs- and his career destroyed. We have now moved some twenty years forward in time and the predicted recoveries of soil and water pH have not been achieved. EPA/NGOs have given two reasons for this- the first that the impacts of acid rain were so devastating that it will now take a hundred years to see improvements (Acid rain taught to always move the model beyond ones lifetime) The other unbelievably is that global warming is causing increased water acidity. (If you believe that increased global warming causes increased precipitation and increased precipitation in areas of granite geology causes the growth of bog plants which produce organic acids and sequester calcium causing a depression in pH-then yes global warming has replaced acid rain. It is a good example how we manufacture truth in today’s academic papers. It has all been done before- perhaps we need to focus on acid rain as a tool to understand global warming and why nothing prevented the suppression of science.
Recent work in crisis psychology says the first information received controls all beliefs framing a perceived crisis. Future conflicting information is disregarded. Alarmism is a first strike strategy for which we have not found a counter strike solution.
History is an important tool- the National Academies of Science was formed as a tool to isolate and marginalize the advocates of Charles Darwin. Only anti- Darwin scientists would be invited to join- a great overview in the book Reef Madness. (Dr. Lindzen’s comments on the NAS process would not have surprised Darwin’s advocates)
Very informative …
It would be easy to see, that if the positive feedbacks were present in the atmosphere, then at some time in the past millions of years, the earth’s climate would already be pegged at one extreme or the other.
“Recent work in crisis psychology says the first information received controls all beliefs framing a perceived crisis.”
I would say first and last … everything in between being just noise. For example, if something is widely disseminated that turns out to be false but the correction is only narrowly disseminated, the “conventional” wisdom will hold with the original information for a very long time. Newspapers and TV rely on this when they lead with a huge story that turns out to be incorrect and bury the correction on page D-34 or in a blurb on a 3am newscast. Everyone saw/heard the incorrect information, very few saw/heard the correction.
Now if the correct information is given as wide a dissemination at the same times and frequency of repetition as the original was, then it would be as widely held as “true”.
Example, place a front page headline and “breaking news” story on every network that a passenger plane was shot down by a missile. Repeat the story for a couple of days. Then once the story is off the front burner, put out the fact that it was mechanical problems and bury that information in a single sentence in a news broadcast and on a back page of the newspaper and poll people 6 months down the road … they will still believe, by and large, that the plane was shot down. But the media will swear up and down that they reported the “facts”.
Same with “global warming” stories. An arm waiving activist gets the headline and contrary information is buried. But the outlet claims “fairness” and that they “reported” both sides.
“”” Chris V. (09:22:48) :
anna v (08:41:15) :
So of course there are negative feedbacks. The most important one iw albedo changes.
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. “””
Anyone who believes that ice cover is a major part of albedo hasn’t been looking at pictures of the earth recently. Pictures like the famous earth rise from the moon show clearly that the albedo is dominated by clouds; about 505 of the earth’s surface at any one time is covered by clouds. Clouds arise mostly where the atmosphere has plenty of moisure and most of the time that is in the hot tropical areas, rather than the cold polar areas. So tropical clouds are reflecting solar energy away from earth mostly at the places where there is more arriving solar energy; namely in the warmer tropical areas (per square metre).
The earth’s ice cover on the other hand, particularly the “permanent ice” is mostly at the poles; Antarctica and the Arctic. Those areas are only obliquely illuminated by the sun and for only short periods of time, so there is much less solar irradiance where those polar ice sheets are.
Hint to Chris and Ian. See if you can come up with a logical reason why those ice sheets are there at the poles. Why aren’t there large floating ice sheets on the equator ?
In terms of earth’s albedo, ice and snow are bit players.
Ice and snow aren’t as refelctive as some people think either. Freshly fallen snow can be quite reflective at solar spectrum wavelengths, as much as 90% relative to a BaSO4 reference, but that can drop in half after a few days exposure. When snow melts under sunlight, you get optically transmissive windows formed on the surface,w hich can then transmit light a long way into a snow pile, and it gets trapped in there by Total Internal Reflection and other mechanisms; so after a few days it might not be any more reflective than trees or grass. But besides all that there’s just not a lot of snow and ice in the same places that have a lot of solar radiation; I know that sounds weird to some people but it is true. Clouds on the other hand behave exactly opposite from snow; they tend to form in places with a lot of incident sunlight (with water present).
Besides, when the artic sea ice melts, that opens up a vast amount ox extra water surface which then takes up CO2 from the atmosphere; which is why you get that 18-20 ppm P-P cycle in the arctic, so that reduces the CO2 GH effect, and allows thermal radiation to escape more easily. the exposure of the warmer ocean waters to the atmosphere, when that ice melts also leads to enhanced radiation from that surface compared to the ice it replaces.
So don’t bet on the melting arctic ocen to have a great global warming effect.
No I’m not suggesting it cools instead; just that it isn’t the big warmer some people think.
George
There actually seems to be hard wiring in the brain for believing the first alarmist information. It frames all future information. Availability is certainly involved in the cognitive bias produced by media – but does not seem to explain everything. First strike is important.
The larger question for me is how to make facts mean something- Acid Rain used the same tactics of reasoned scientifc debate as is being followed on this site and failed. In fact all one needed to do to open debate concerning the acid rain paradigm was to pour some distilled water through peat moss and measure the pH. Acid rain alarmism could have been tested in a high school chemistry class and yet was unable to convince the EPA, NGOs, media or the Public. Global warming is far more complex an issue. The facts presented about AGW on this site are correct, however, acid rain teaches the strategy is failed. We need a new strategy to present the facts.
“”” Ed Fix (07:51:37) :
INFRARED IS NOT HEAT RADIATION!!!! “””
Ed, I’m in agreement with you; but it could be nothing more that Prof Lindzen being a bit less than pedantic with his terminology; which is always a problem when dealing with possibly lay audiences. that’s partly why I flagged the “long wave” / “short wave” terms. I doubt that Dr Lindzen doesn’t know the difference.
The way I like to put your objection is by saying “HEAT IS NOT A NOUN !”
And I was certainly not the first to make that observation. One way to put it would be to say that “heating” is the process by which other forms of energy, are converted into the purely mechanical Kinetic energy of atomic or molecular agitations. In that sense “heat” (not a noun) cannot propagate through a vaccuum, although radiation certainly can.
Inevitably when scientists try to communicate with lay persons; the accurate scientific terms may become very stodgy and perhaps not helpful, so you either have to laboriously explain those terms, or else try to put it in a more “user friendly” way (and words) and thereby lies confusion.
I can’t hold that against Lindzen; I’m Happy he made the effort to be communicative.
George
J.Hansford (02:06:52) :
“Is our democracy strong enough to override the massive political impetus that AGW has built up….? After all, there is a whole green Socialist agenda relying on those carbon taxes and emission trading schemes…. and the careers of those that have attached themselves to a lie. Whole industries are gearing up to go green.”
It’s already happening. The foundations for cap and trade were in legislation last year. Bits and pieces of the green agenda were in the stimulus bill. A bill was submitted to the house yesterday to create a ‘Green Bank’–kinda lika Fanny and Freddy but for the green agenda ostensibly to help finance the grid to make it smart and to hook up all those G.E. wind turbines and solar panels.
The GM bailout is using the techniques of bankruptcy to let the government decide which plants to keep open and which to close. I doubt we’ll be surprised by the demise of the Hummer and probably SUVs as well. The incentives to purchase autos give you more of a break the greener the car you purchase.
The 2 million acres set aside as protected land also protects the waterways running through them and much of this new land is in states such as West Virginia—goodbye coal mining–and a couple out West–goodbye oil shales.
Obama has already cut funding for Yucca mountain research–goodbye nuclear power. He’s already reinstated the offshore drilling ban.
There’s more. The above is just off the top of my head. Obama is smart–he wouldn’t do this in the open and all at once because he knows there would be a huge backlash. The greenies, however, know exactly what he’s been up to.
This is the face of ‘energy independence’. Not independence from foreign oil, but independence from carbon.
And what is making it all worse is the war on capitalism because of this financial crisis. The forces of the green movement, the anti-capitalists, and the warmers have all converged. And America is left dependent on a dozen blue dog Democrats in the Senate who have no clue as to what just hit them.
re feedbacks
As I understand it before each glaciation started the Arctic may have been ice free (and sea levels were higher than today). The warmists always warn us that an ice free Arctic will mean less albedo and further warming due to this positive feedback. I think the opposite occurs–negative feedback. Less ice means more ocean cooling. In fact I think this may have been a causitive factor (or I could be all wet) in the cold cold winter we had after the ‘unprecedented melt off’ of Arctic ice a couple of years ago.
Oh, and if we’re worried about the next glaciation (well, we should be, we just don’t know when) and cannot depend on CO2 to warm us out of falling into it there is another possible solution (besides the ones mentioned by anna up above)…..
we can blow up Panama 🙂
Is it just me? Am I that smart and everyone else that stupid. Isn’t it obvious that for life to exist on earth there must be a strong negative feedback effect in place. Without strong negative feedback does anyone sane really think that the climate on earth would remain stable enough long enough for life to evolve and prosper?
No worries – many people must have concluded much the same, at least I did.
It does not take a rocket scientist to figure out that the atmosphere must somehow be inherently stable. High school calculus comes to mind “minima” and “maxima” – indeed if we happened to be sitting on a highly sensitive and unstable atmospheric maxima then surely things would have gone completely awry 100 years, 1000 years, 10,000 years, 100,000 years, 1,000,000 years, 10,000,000 years, 100,000,000 years, or 1,000,000,000 years ago ! Clearly there are stabilizing phenomenon (negative feedbacks) that we don’t yet fully understand.
I am surprised that any logically minded scientist could accept a model that had positive feedbacks and was therefore inherently unstable. Things that are inherently unstable tend to come crashing down sooner or later – like a coin placed on its edge.
If the logic goes more CO2 => hotter temperature => less clouds => even hotter temperature => even less clouds => even hotter temperature etc. etc. then it clearly makes no sense viz a viz what we observe …even a child can see that.
Onset of Ice Ages:-
Ice Ages are cyclical in the Earth’s recent (last 30m years) past.
Original cause:-
Continental Drift of Antartica over the south pole 40m years ago. Ice pack at first formed over mountainous regions. This caused a negative temperature feedback due to the increased albedo, eventually the entire continent was covered with ice. This permanently reduced the surface temperature of the earth.
Cyclical Ice Ages – Why?
Once the surface temperature is lowered, the variability of the Earth’s orbit around the sun which causes a variation in the balance of solar radiation NH/SH summer/winter leads to summers cold enough to allow snow to remain unmelted and to accumulate.
Prior to the Antarctic moving over the South Pole, this would not happen as the earth’s surface would have been too warm.
The 3 parameters and periodicity is as follows:-
Orbital eccentricity varies between 0 (a perfect circle, sum always 93m miles away) and 0.1 ( min 88m miles max 98m miles) , period 100,000 years.
Axial tilt varies between 22.5 and 24.5 degrees , period 41,000 years.
Precession of the equinox , period 26,000 years. This parameter determines which month the summer solstice occurs, and impacts on the first 2 variables.
To start an Ice Age, the above parameters cause a lowering of solar radiation in the NH in summer. Snow does not melt from the previous winter and a negetive temperature feedback driven by increased albedo sets in. The Ice marches south. Typically all of Canada, the Northern part of USA all of Scandinavia and most of Northern Europe have permanent Ice sheets. Obviously, Greenland and Antartica remain Ice covered.
To end an Ice, the opposite to the above. i.e. increased solar radiation at the in NH summer.
As Ice ages typically last 10 times longer then the inter-glacials, it seems clear that Ice Ages are easier to start then to end.
If the conditons are right, a run of cold winters caused by something like a Maunder minimum solar event could be enough to tip the climate into an Ice Age. This might be less than 100 years from interglacial to Ice Age, though of course this is hard to prove.
Current orbital parameters would sustain an Ice Age, all that is needed is a Maunder minimum to push the climate over.
Something else to ponder, at the moment the Sun has entered a long period of quiet. This is not a Maunder minimum, yet.
Dr. Lindzen is one of the scientists I respect most, however he is being bashed in the media and by certain groups. When you can not debate someones ideas, you attack the person, and that is beginning now to pickup.
pmoffitt (11:24:00) :
. Global warming is far more complex an issue. The facts presented about AGW on this site are correct, however, acid rain teaches the strategy is failed. We need a new strategy to present the facts.
We need a deus ex machina, because the whole AGW thing is into myth and magical thinking.
Fortunately the gods seem to be with us, what with cycle 24 dragging its feet and the PDO etc turning cool, one or two such harsh winters in the EU and US and wet cool summers will do much more than any scientific expostulations could.
One could say that Gaia loves CO2 and does not want to be deprived of it :).
I’m having a problem with this:
“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).”
Is he saying that the Earth emits radiation at 255K? Because that’s just not true. I’m sure I’m just misunderstanding something, and would appreciate someone ‘splaining it to me.
Thanks!
anna v (10:26:51) :
Has none of you looked up and seen clouds? Or do you think all that ice during ice ages came by magic?
No- from milankovich cycle induced changes in ice albedo, plus various positive feedbacks.
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.
George E. Smith (11:07:59) :
“In terms of earth’s albedo, ice and snow are bit players.”
I’m pretty sure that going into and coming out of a ice age, ice and snow are the most important players.
Water vapor creates clouds that act as negative feedback, but also the water vapour itself acts as a greenhouse ‘gas’ so that is positive feedback. The switching from one to the other should show up in temperature data going into and coming out of ice ages as a gradual change in the rate of temperature change. I don’t see that in the temperature data.
tarpon (10:40:59) :
“It would be easy to see, that if the positive feedbacks were present in the atmosphere, then at some time in the past millions of years, the earth’s climate would already be pegged at one extreme or the other.”
Exactly. How do we know that it isn’t pegged to an extreme right now? I think it is. Not sure why that is so implausible to some.