Arnold Kling via Cafe Hayek on macro-economic modelling:
We badly want macroeconometrics to work. If it did, we could resolve bitter theoretical disputes with evidence. We could achieve better forecasting and control of the economy. Unfortunately, the world is not set up to enable macroeconometrics to work. Instead, all macroeconometric models are basically simulation models that use data for calibration purposes. People judge these models based on their priors for how the economy works. Imposing priors related to rational expectations does not change the fact that macroeconometrics provides no empirical information to anyone except those who happen to share all of the priors of the model-builder.
So you’re saying that because economics is not physics, then climate models must be rubbish. Right?
I’ve suggested some interesting correlations between climate models and economic models. Both are dependent on examining correlations and trying to unpack intermixed factors. There are economic cycles just as there are climate cycles. Feedback mechanisms are employed (when share prices go up they tend to continue to go up and visa-versa). Tipping points exist, i.e., stockmarket crashes.
Of course, the fact that there are interesting analogies doesn’t necessarily mean that these research fields are sufficiently alike for one to shed light on the other.
Processes and procedures are generally similar though. Measurement of data that is sometimes difficult to gather and imperfect, and a great deal of pure maths and statistics to derive results. I’ve been lead to believe that data archiving policies in the more mature field of economics is something that climatology scientists could learn a lot from, particularly since the type of information both fields deal with are similar in a number of important respects.
hunter,
You are guilty of creating a classic straw-man argument. Right?
The post is just pointing out there are limits to computer modeling of real world systems and the more complex the system, the harder it is to model. I don’t see where anyone claims it makes climate models “rubbish”. You wrote that. Many skeptics find global climate models USEFUL for many things, but don’t necessarily believe they are good enough to be used for long term projections (or that their projection error is correctly represented).
Crichton pointed out the same thing. Man’s attempt to create simple graphs and models to explain extremely complex things is arrogant and laughable.
For what it’s worth, I think it would be even harder to model macroeconomics than climate, because you almost have to model the human brain 🙂
Luckilly climate models don’t require nearly as much human input LOL
i think you are very wrong about economics being more difficult to model than climate. (as i happen to have degrees in both physics and in economics, i am in a decent position to make a comparison.)
there are several important differences. to model economics, one need not predict individual behavior, just aggregate behavior. this is much more easily done. we also have a much better sense of what the relevant input variables are. we have first hand knowledge of how economic decisions are made (at least at the corporate and household level), something we lack in evaluating climate.
economic cycles are also quite brief in comparison to climate cycles. this means we have more of them to look at and test data, and that many theories posited in the past can be evaluated on how well they predicted future events. such a process of making predictions and then comparing them against what happens is a vital part of hypothesis testing.
in climate, we are really just beginning to understand how the PDO (or el nino/la nina) affects temperature (it was, for a long time assumed that they just redistributed heat as opposed to increasing or decreasing it).
in comparison to our economic models, or climate models are terribly uncertain as to what the key variables evn are, much less how to predict their influence and interaction.
Having advanced degrees in both economics and the physical sciences, I will agree with morganovich on this issue. Above all, humility is a prudent trait while building these models. Although my econometric models were quite reliable for the items of their focus, they had a narrow focus, and I did not use them for projections of over eight years. Moreover, the profession’s performance of forecasting interest rates is quite abysmal. However, forecasting climate is even more challenging. In climate models, the cycles are longer, the chaotic inputs and interactions are less understood, the data are of more questionable validity, and the impact of key variables is more controversial and sometimes ignored.
I think the most important characteristic of both economists and AGW promoters is their reliance on models, lately at the expense of actual data.
The infamous Long Term Capital Management ecnomists relied on models that were not reliably back tested at all. They had won the Nobel Prize in Economics.
http://en.wikipedia.org/wiki/Long-Term_Capital_Management
But it is not so much that scientists are over relying models, it is that policy makers are accepting this reliance on models instead of using critical thinking skills to make tough decisions.
Group think, is easily the biggest problem we face. The economic and finance debacles, and the popularity of AGW, are all aspects of this pernicious problem.
I don’t think I believe that either of you have the qualifications you claim. It is as implausible as someone claiming to be a botanist and telling you that apples and oranges were the same thing. You’re trying to draw comparisons where absolutely no meaningful comparison at all can be drawn, any more than one could be drawn between climate models and fashion models. And why are you doing this? Seems to be some kind of attempt to rationalise an irrational dislike of climate models.
hunter(the phony one),
You are missing the point completely, as usual.
And it seems that cliamte models ahve some serious problems any way:
http://climatesci.org/2009/02/09/update-on-a-comparison-of-upper-ocean-heat-content-changes-with-the-giss-model-predictions/
Once again, GISS fizzes out in the real world.
hunter: By your reasoning, calculus would be useless for electromagnetic calculations because it was developed to solve a physics problem – and yet when I switched from physics to electrical engineering, the calculus problems just got tougher.
A mechanical engineer calculating heat flow in a complex solid and an electrical engineer calculating electric fields will use the same computer model – the equations are the same. Climate models and economic models are not identical in that way, but there is a lot of commonality. Both attempt to model chaotic systems. Both attempt to make up for poor understanding of the underlying relationships by adjusting the models and shoving in fudge factors to fit the model to past events. And neither can be expected to accurately predict events very far into the future or in conditions different from the past data, because the adjustments and fudge factors are very unlikely to represent the actual underlying relationships.
markm: my reasoning would not lead you to that conclusion. My reasoning is simply that one of the things we’re talking about has a set of physical, repeatable, fixed laws, i.e. physics underpinning it, while the other does not. That is the insuperable divide that renders the comparison meaningless.
There is no consistent evidence to suggest that climate models are any better than economic models, regardless of (phoney)hunter’s ‘philosophising’ that they must be (in theory). Some peer reviewed papers show that they do have some predictive skill, yet many other peer reviewed papers suggest they have none at all. So the jury is still out on that one.
“many other peer reviewed papers suggest they have none at all”
Maybe in the dream world you inhabit that statement is true. In the real world, it’s fiction.
It seems the AGW promoters can only thrive in a climate of intimidation and confusion and untruths.
The common link Jennifer is studiously avoiding is that both economics and AGW depend on models that claim to fully represent reality, but, as the actual events show, not only do not, but end up leading to huge costly mistakes.
There is the old saying of ‘mistaking the map for the territory’. AGW and economics both demonstrate this.
actually, “hunter” possessing degrees in both economics and physics is fairly common in the quantitative hedge fund community.
i would re-vamp my thinking on long term capital were i you. you appear to both misunderstand what happened there and the role of back testing in models. if i had a nickel for every model i have seen back test but provide no predictive money making value at the far right hand edge of the chart, i would not still be in this business…
winning the nobel prize for options pricing models (and black and sholes was a major breakthrough, no mistake) does not make you a good risk manager…
but i think the point made several times above holds true: modeling complex phenomena, particularly over any sort of long term time frame is very difficult, and in many cases far beyond our current capabilities.
pretending we can model climate over the next decade (much less the next century) is even more foolish that pretending me can predict economic growth over a like period.
we frequently complain about the inability of weathermen to predict what the weather will be just a few days into the future. data from them extending beyond about 10 days is nearly meaningless. but somehow if we go out 10 years, we can assume this uncertainty magically goes away? no other physical science would tolerate such shenanigans.
markm-
another interesting commonality between economic and climate models is both are frequently used to support policy decisions. this makes both highly prone to bias about outcomes creeping in. this is an issue that even diligent, well intentioned modelers making every attempt to be impartial need keep a constant lookout for. (and i fear that in both fields, there is a great deal of agenda driven research going on)
selection bias and even mild slant in assumptions about the interrelation of inputs can have major impacts on output, and it is surprising how frequently researches seem to come up with the answer they expected.
one of the reasons i tend to trust wall st economists more than government and most academic ones is the simple fact that if they don’t make decent predictions and make money, they get fired. this tends to cull out the worst of the bunch, whereas in government and academia, they just twist the assumptions around again and again until it turns out they were right all along! one might be led to ask which of these 2 categories (held responsible for predictions/allowed to weasel out endlessly) folks like jim hansen fall into….
hunter (the idiotic one): “models that claim to fully represent reality” – another one living in a dream world! What are you smoking? No-one has ever, ever, ever claimed such a thing.
morganovich – I’m not saying it’s not common. I’m saying you don’t have both. If you do, it just makes it even more embarrassing that you could make such a howler as comparing physics with economics.
“we frequently complain about the inability of weathermen to predict what the weather will be just a few days into the future. data from them extending beyond about 10 days is nearly meaningless. but somehow if we go out 10 years, we can assume this uncertainty magically goes away? no other physical science would tolerate such shenanigans.”
This really is the most fatuously stupid thing you could say. Really. I thought that even the most lobotomised ‘skeptic’ had given up with this idiocy. Do a little thought experiment and imagine the Sun suddenly got twice as luminous, overnight. Do you think a) global temperatures would rise in response; b) global temperatures would fall in response, or c) it’s just such a complex system and we can’t predict whether it will rain three Sundays from now and so we couldn’t possibly tell, and your guess is as good as mine, and anyone who says they know it would rise is just a big fat liar.
The climate models are great and have many uses; I just don’t trust them for long-term projections. Where have they been scientifically proven to be long-term predictors? All I’ve ever heard is where people match them to history. That is scientifically laughable as it clearly fails to provide a long-term prediction and ensuing observation for independent comparison (the prediction is based on the observation after the fact). If a psychic gets a hold of the papers in my wallet I’m sure they can give me quite a good reading too!
Jennifer,
If the AGW models are not accurate, why are we spending so much time dealing with them?
If the AGW models are not accurate, why do you spend so much time trolling here and attacking anyone who questions them?
And if they do not fully represent reality, what do they represent?
Valerie: your binary view is very stupid. There is rather more choice than “climate models are not accurate” and “climate models are perfect”.
hmmm: doesn’t look like you’ve read any of the literature then. An exercise for you: go back and look at papers about early climate models. For rising concentrations of greenhouse gases, did they predict a) surface warming, or b) surface cooling? Did they predict a) stratospheric warming, or b) stratospheric cooling? Did they predict a) greater response at the poles, b) greater response at the equator, or c) equal response globally? In each case, what has happened in reality?
Jennifer,
Answer my questions, then I answer yours.
Evasive misrepresentations of what I ask are not answers. They are simply evasions.
I’m concerned with their use as long term soothesayers
I don’t feel like doing homework but I’ll go from memory. The models predict slower cooling at the South Pole because of the larger heat capacity of the southern hemisphere (more ocean to absorb the heat and hide the signal). I believe the first models predicted warming signals wouldn’t be seen there for a few decades for a doubling of CO2. In reality, over 50 years of the heaviest CO2 output, the measured warming at the South Pole is less than the actual error in the thermometer measurements (not statistically significant). Also over the last 3 decades there has been cooling at the South Pole. Climate Scientists have simply searched for reasons to increase the delay and now simply say it’s somewhere in the future (definitely supposed to be the last place to warm, not sure when). Of course you can always find enough tweaks in one direction if that’s all that you’re looking for. The climate is very complex and there are plenty of relationships to look for and find.
I meant slower “warming” at the south pole (not slower “cooling”). Baseically there is supposed to be a delay because of the energy absorbed by the ocean, with greater effect in the southern hemisphere because it’s more ocean.
That’s what I mean about the models being useful; they can explain many relationships and such. However showing that events a and b are related this way to c and d doesn’t validate that a and b lead to e and f…
hunter-
your utter lack of basic understanding and logic is breathtaking.
i have not seen you utter one useful or even sensible thing in this entire thread.
your first post shows an utter lack of basic reading comprehension and logic. it just gets worse from there.
accusing people you know nothing about of being liars adds boorishness to stupidity on your list of defects.
what are you doing here? you contribute nothing, disparage others, fail to grasp the issues discussed and other peoples views on them.
seriously, what are you getting out of this?
is this some sort of mental problem?
and for the record, i do indeed have ivy league degrees in physics as well as economics.
based on your responses thus far, i would have a difficult time believing you could even earn the sort of degree that comes with a free set of tools.
your example of doubling solar output is an incredibly stupid oversimplification. the effects would be incredibly obvious. but how do precipitations systems and water vapor respond to temperature changes of tenths of a degree? how does the feedback work? what other inputs affect them? are you claiming we know how that system works and can model it? if so, why do all the models have the opposite sign of water vapor feedback than the one observed by NASA’s AQUA satellite?
if the models are so good, why have none exhibited predictive capability even on a decadal timeframe.
you accuse others of evasion, but never answer questions posed to you save with ad hominem attacks and rubbishy rhetorical dodges.
so answer the questions.
hmmmmm,
When has CO2 doubled, and are you not aware that the AGW position is now that Antarctica has been warming since 1957?
http://dsc.discovery.com/news/2009/01/21/antarctica-warming.html
But what, if the models do not fully represent reality, do they represent?
hunter: “My reasoning is simply that one of the things we’re talking about has a set of physical, repeatable, fixed laws, i.e. physics underpinning it, while the other does not.”
Hmm, are you asserting that your brain doesn’t work according to the laws of physics and chemistry? Not that it’s possible to model even one brain that way, let alone the billions of them influencing the global economy.
I have done modeling from the laws of physics. To get results anywhere near reality, you have to use a cell size small enough that any relevant objects in the real world are represented by several cells. For climate modeling, that means clouds (which have a very large impact on both incoming sunlight and outgoing infrared) must be represented in cells under 1km – but computer technology is still a few orders of magnitude short of being able to run a model with that many cells in it. So they use cells 10 km or more in size, and try to account for clouds and other things not well simulated by that model with fudge factors that are empirically adjusted to fit past data. But it’s a chaotic system; small errors accumulate and soon render extrapolations meaningless.
hmmmmm: the answers were that a, a and a were predicted. a, a and a have subsequently been observed. Your description of what climate science has to say about Antarctica is ridiculously wide of the mark.
morganovich – you’re becoming unhinged. All those one-sentence paragraphs!
Anyway it’s good that you seem to have realised that ‘climate’ is something different from ‘weather’, and even you can imagine what doubling solar output would do to the climate. Now, that was a thought experiment involving a change in the incoming short-wave radiation. Imagine now that the atmosphere suddenly starts absorbing twice as much infrared radiation. Do you think a) global temperatures would rise in response; b) global temperatures would fall in response, or c) it’s just such a complex system and we can’t predict whether it will rain three Sundays from now and so we couldn’t possibly tell, and your guess is as good as mine, and anyone who says they know it would rise is just a big fat liar.
markm: you could probably have a bash at deriving some basic equations describing the climate system, from first principles. You could never in a million years do the same for human behaviour. In that sense, human behaviour has nothing at all to do with physics.
So what have you constructed physical models of? I don’t see that cell size is as important as you seem to think. See for example the colossal amount of literature on modelling of ionised nebulae in space, much of it with 1D codes.
Jennifer,
Everyone knows it is you.
It is typical that you would skip from climate to astronomical observations and pretend that shows cell size on Earth is not important.
So if a model does not represent reality, what does it represent?
And, by the way, you are still a compleat troll.
Valerie you fuckwit. Who said models don’t represent reality? You did, you retard.
And by the way, learn to spell.
Jennifer,
Learn to think.
It will be a big improvement.
http://www.answers.com/topic/compleat
Jennifer/Scientist,
Your lack of integrity is only matched by your inability to communicate beyond grunts and belches.
And, by the way, learn to spell your self:
http://www.answers.com/topic/compleat
New knowledge is really tough for trolls like you that know everything, but give it a shot.
And everyone still knows it is you and you are indeed a compleat troll.
Jennifer/Scientist,
What did I mis-spell in the post you ‘responded’ to?
Certainly not ‘compleat’?
http://www.answers.com/topic/compleat
Besides being a compleat troll, you are a compleat imbecile.
http://www.answers.com/imbecile
And for believing in apocalyptic models, and defending them so rudely,
you are also a compleat dupable imbecilic troll
http://www.thefreedictionary.com/Dupable
hunter,
I didn’t say CO2 doubled, that was simply a reference point used in many models (you asked for the history of models no?)
Did you know that the recent finding on Antartic warming trend over 50 years is the result of “infilled” data (wasn’t actually measured by a station/observer/anything). You can even many AGW proponents who find the recent Steig study dubious. I believe one of the quotes was: it’s hard to make data where none exist. Did you know that the measured warming trend they got as a result is less than the calculated error? In the science world that means it is insignificant at best. Interesting that when there is cooling or no warming in the Antartic, you get to call it natural or masked by the oceans, but if you make up a crappy study that shows an insignificant warming, BOOM that is AGW buddy yeah! Give us a break.
“markm: you could probably have a bash at deriving some basic equations describing the climate system, from first principles.” Sure I can take laboratory measurements of the absorption spectrum of CO2 and calculate how increased atmospheric CO2 will affect the radiative heat exchange of the Earth, assuming there’s no effect on albedo and other greenhouse gases. The result is a temperature increase of a fraction of a degree, not the several degrees that the alarmists are worried about. But that’s a bogus assumption, considering that heat moves water around the system, and water vapor, clouds, and snow each have a much greater effect on the radiative balance than CO2. On a longer time scale, CO2, precipitation, and warmth all affect plant growth, which changes albedo, temporarily absorbs CO2, and releases water into the air. It’s those effects that are impossible to model with anything but fudge factors.
“So what have you constructed physical models of?”
Control systems. Which, if they have positive feedback of the magnitude that the AGW crowds models have to assume to get several degrees temperature rise from CO2 increases, are unusably unstable. That is, they either oscillate wildly, or go to an extreme where a shortage of something or other ensures the system can’t go further, and stay there. Neither way do you get anything resembling the climate of the last 8,000 years. (Possibly you could get a cycle resembling the ice ages, but only if you can find a mechanism to delay feedback for about 10,000 years.)
And back when I was young and foolish, I made an attempt to derive the laws of chemistry from basic physics, modeling the Schroedinger wave equation of atoms in close proximity. I learned a hard lesson in the limits of computer modeling (not saying it can’t be done now, but it takes a whole lot more computer power than was available then).
To all,
There was no intention to post so many posts to Jennifer. My posts were not showing up on this thread, so I was (mistakenly) concluding that my posts were being rejected.
Please accept my apology for the multi-post responses to Jennifer.
markm: why do you think these things are impossible to model? Impossible is a strong word which needs strong justification.
You should not be surprised that if you model something that isn’t climate, you don’t get something that looks like climate. And by the way, wild oscillations are the defining feature of the geologic climate record.
hunter-
again, you make my point for me. you fail to grasp the basic issue, distort and flat out invent other people’s positions, and fail to answer any questions posed to you, instead hiding behind a smokescreen of invective and oversimplification. (as well as the consistent adoption of other people’s names to confuse matters)
a doubling of solar output would likely make the earth so hot that liquid state water could not exist. it’s also an incredibly unlikely event. all the answer demonstrates is that we know the sign of the effect of a change in solar output upon earth temperatures. i dobt anyone argues that a hotter sun will not result in a hotter earth.
a more relevant question would be “how much would a 0.1% decrease in iradience alter earth temperatures?” do you think anyone really knows?
at least back in the days of “scientist” some actual data was injected into the conversation.
i urge you to
If wild fluctuations are the norm of climate, then why are we concerned about the one we are allegedly causing?
“it’s also an incredibly unlikely event” – well duh! Don’t you even know what a ‘thought experiment’ is?
If you really think that asking ‘how much will temperatures change’ is better than asking ‘will temperatures change’, then you’ve actually already got over the worst of your denialism. You’re asking the question that all serious scientists are asking. You almost certainly believe the wrong answer, but it’s a start.
hunter – god, the stupidity doesn’t get any better does it? Have you received a brain injury at some point? Here’s a tip – try googling ‘climate change mass extinction’, and see what you can learn.
will-
your response does not appear to make any sense. who ever said that solar output was not correlated to temperature on earth? how does thinking that how much effect a reasonable and likely change might create constitute a refutation of “denialism”?
my point is precisely that we have very little ability to predict the effects of such alterations in sun (or CO2 where, frankly, there is a great deal of evidence that CO2 is more of an effect of temperature increases as opposed to a cause. note that mistaking a cause and effect relationship can easily create a false impression of positive feedback.). this would seem to imply that our understanding of the climate system is weak. if such is the case, (it it seems irrefutably so) then we are in no position to be making dramatic (and expensive) policy decisions based on the output of models with no predictive ability.
taking the view that AGW is proven until disproven is simply not how science works. a hypothesis must be positively proven, and this has not been done.
morganovitch. It’s so simple. You are obviously one of the self-lobotomisers who refuses to understand something very easy, just so you can maintain a perverse viewpoint. Temperature is determined by the balance between energy in and energy out. You clearly understand that changing the energy in will affect the temperature, but you refuse to believe that changing the energy out will do the same. Why?
And you don’t think you can predict the magnitude of the effect of alterations in solar input? You think we just don’t know whether day is warmer than night? Or whether summer is warmer than winter?
will-
do you honestly think we have even a rudimentary understanding of the energy in and energy out balance and how all of the various factors affecting each interact? we have no idea how much a .05% decrease in irradience affects temperature. there are an enormous number of factors and feedbacks involved. this is not like turning up the gas on a stove. we lack predictive capability there, and it is one of the things that has been studied most. the farmer’s almanac has consistently outperformed GCM’s by using sunspot numbers, but is this an irradience issue, or a solar wind issue? how do the two interact? that seems to be hotly argued. solar irradience was very high throughout the latter half of the 20th century. by your own argument, should we be surprised that it warmed? i presume you will not argue that man somehow caused the sun to be stronger. the little ice age, which ended in the early 1800’s was the coldest period for 9000 years. given the tendency of temperature to revert to a mean, should we be surprised to see warming? notions that this must, somehow, have been caused by man are highly suspect.
CO2 is a lagging variable to temperature on both long and short timescales. can you point to even one actual empirical piece of data that it drives climate? does it impact climate, almost certainly, but if the impact great enough that it can significantly alter the prevailing equilibrium in the way that a malinkovich cycle can? of this, these is precisely zero empirical evidence. in the past, the earth has had CO2 levels 20X those currently prevailing. climate never “ran away” there were no unrecoverable tipping points. these exist only in models. the fact that they exist in the models is a strong indication that they do not model climate accurately. most models are dominated by positive feedback. can a climate system that for over a billion years has varied less in temperature globally than much of the earth varies day to night possibly be dominated by positive feedback? it seems impossible.
water vapor absorbs a much broader spectrum of radiation than does CO2 and overlaps it and there is 20X as much of it in the atmosphere. at which should we be looking? if the impacts of CO2 on climate are well understood, why do the GCM’s fail to accurately model climate in either the past or, more importantly, in a predictive capacity? nearly all GCM’s assume positive feedback from water vapor despite the fact that this was disproven by NASA’s AQUA satellite which showed precipitation systems to be net reducers of heat and provided support for lindzen’s “adaptive heat iris” hypothesis.
my argument is that using these deeply flawed and incomplete at best (and deliberately manipulated at worst) models to attempt to make public policy is like attempting to use elliot wave theory to run fiscal policy.
That was a long, ranting post. Here are some simple answers:
“do you honestly think we have even a rudimentary understanding of the energy in and energy out balance and how all of the various factors affecting each interact?”
Yes.
“we have no idea how much a .05% decrease in irradience affects temperature”
Yes we do, and here it is. That would correspond to a forcing of -0.12W/m². Estimate of the climate sensitivity are generally around 0.75K/W/m², so we can estimate that a 0.05% decrease in solar irradiance would cause a 0.09°C drop in global temperatures.
“the farmer’s almanac has consistently outperformed GCM’s by using sunspot numbers”
Simply a lie.
“solar irradience was very high throughout the latter half of the 20th century. by your own argument, should we be surprised that it warmed?”
No, but we should be surprised at how much it warmed. This has been extensively studied, and even with outlandish and clearly incorrect assumptions, you cannot attribute more than a third of the warming since 1970 to solar changes. Papers by Solanki et al and Lockwood & Froehlich would educate you on this, if you were capable of being educated.
“the little ice age, which ended in the early 1800’s was the coldest period for 9000 years”
Pray tell what climate reconstruction you are using that goes back 9000 years.
“given the tendency of temperature to revert to a mean”
There is no such tendency.
“CO2 is a lagging variable to temperature on both long and short timescales”
No it isn’t. Its industrial era rise clearly precedes the subsequent rise in temperatures.
“can you point to even one actual empirical piece of data that it drives climate”
See previous answer.
“in the past, the earth has had CO2 levels 20X those currently prevailing. climate never “ran away” there were no unrecoverable tipping points. these exist only in models”
Climate runaways have not just happened in the past, but are the defining feature of the geologic temperature record. You have heard of ice ages, right?
“can a climate system that for over a billion years has varied less in temperature globally than much of the earth varies day to night possibly be dominated by positive feedback? it seems impossible.”
‘dominated by positive feedback’ is meaningless. Define your terms. And remember that arguing from incredulity only makes you look stupid.
“if the impacts of CO2 on climate are well understood, why do the GCM’s fail to accurately model climate in either the past or, more importantly, in a predictive capacity?”
They do not fail in either respect.
“this was disproven by NASA’s AQUA satellite”
No it wasn’t.
Your argument is just a car-crash of bullshit that is flatly contradicted by all current serious research. I predict that you will not be able to cite any recent research in support of your claims, but neither will you be able to accept that you are wrong, and we will see you make the same wrong claims again in the very near future. Let’s see how my model of denialist behaviour performs against the observations…
Jennifer,
Your dismissial of something does not mean what you dismiss was wrong, or that you are right.
You dodge around climate reconstructions of 9000 years when AGW promtoers regularly use reconstructions of X00K years and even Megyears.
Your entire diatribe is like this: If you do not like something, why it must not be so.
will-
plugging a variable into a model that has no predictive ability and then calling the output “data” is not science, its wishful thinking. there are lots of models that TRY to predict climate response. but none seem to get it right. so your answer is simply garbage in, garbage out. until you show me a model with predictive capability, your answer is just noise.
lots of sediment and ice cores go back 9ky and further.
where do you get this CO2 data about precession. that’s just flat out wrong. it lags by hundreds of years in the vostok cores, and by 6-9 months in terms of growth rates when compared to 30 year satellite data. evidence that temperature drives ocean outgassing and CO2 increases as opposed to CO2 being a primary temperature driver seems to exist in all timescales. and mistaking cause and effect looks like positive feedback. and you “see previous answer” show a serious lack of scientific understanding. coincidence is not causality. your argument is equivalent to arguing that opening umbrellas makes it rain.
150 million years ago, there was 5X as much CO2 as currently sits in the atmosphere. it failed to create high temperatures. why was that?
dominated by positive feedback means that a model gets run away responses from recursive feedbacks. eg. co2 goes up, warming the planet, increasing water vapor, which warms the planet, which increases water vapor etc. they tend to have “tipping points”, like those we hear so much about from gore and the IPCC.
“they do not fail in either respect”. that is an outright lie. show me one accurate model that explains the past even moderately well without using piles of special adjustments and has evinced any predictive capability.
you again fail to provide any meaningful data to back up your views.
i miss “scientist”. at least he provided data.
oh, and regarding AQUA:
yes, it was. read this:
http://www.drroyspencer.com/research-articles/satellite-and-climate-model-evidence/
Which models are you referring to? Until you specify exactly which model run you are comparing to exactly which data, and exactly which criteria you are using to assess the accuracy of the projection, your comments are meaningless. For some hints on how it is done by scientists, read this comparison of model projections to recent observations.
Yes, lots of reconstructions go back 9kyr. I asked you which one you were using.
You seem to think that the current rise in CO2 is due to oceans outgassing. Perhaps you could point us to the observations that show CO2 concentrations in the oceans declining. Please also explain what you believe is preventing the rise in CO2 concentrations from having an effect on the temperature.
Very typically for an idiot denier, you seem to think that by posing easily-answered questions and not even attempting to give an answer you are somehow being very clever. Do us the maths – calculate the forcing due to a factor of five drop in CO2, and also the forcing due to the rise in solar output over that time. You probably didn’t know that stellar luminosity increases constantly during the main sequence lifetime of a star, did you?
You still obviously don’t understand that runaway responses are not just possible but observed, and not just observed but are the defining feature of the climate over the last several million years. Do you not believe in ice ages?