climate model

Real time global wind map

illconsidered — Fri, 20 Dec 2013 10:49:04 +0000

Real time global wind map

Filed under "Wow, this is cool!" we have a global real time wind map! (click the image)

The "About" page is here. Don't miss the fact that you can zoom in.

illconsidered Fri, 12/20/2013 - 05:49

What does Climate Model output look like?

illconsidered — Thu, 16 Jul 2009 06:29:24 +0000

What does Climate Model output look like?

Lots of FUD about climate models get thrown around in the Climate Wars, but what is it they are really doing anyway?

The contrarians would have us believe they just take in a bunch of contrived parameters and spit out the worst case possible scenario for global average temperature increase. But the truth is the kinds of models the IPCC report on are very complex and nuanced.

Since I'm no expert and pictures are worth thousands of words, I would like to offer a few beautiful video realizations of GCM output.

The first is from the National Center for Atmospheric Research (NCAR) CCSM climate model and shows a single month of global weather in 25 seconds. Aside from being a beautiful thing to watch, I find it very fascinating. (h/t MT)

(source - and a larger image area)

Notice the incredible detail of weather patterns, the circumpolar wind current in the southern hemisphere, the flowing storm fronts, the tropical cyclone forming out of the Indian Ocean near the end, the daily pulsation of tropical precipitation over middle Africa and the Amazon rain forest. These things are not painted in after watching satellite feeds, they arise from the physics that is programmed in. I don't claim that all the resolution and nuance you see is right out of the numbers, I am sure that graphic "dots" were connected to smooth the coarseness of the grids the model work out of. But the general correctness of the large wind patterns and storm tracks means they are doing something very right.

The next one takes much longer and is output from Japan's Earth Simulator running the Hadley Centre's HadGEM1 model. Unfortunately it is too long for YouTube's 10 minute limit (I tried). You can find and view it here. (I wonder if this is the project James Annan is involved in.)

I prefer the other from a purely visual standpoint, but with this one you can watch the arctic sea ice grow and retreat.

The last is the Nonhydrostatic ICosahedral Atmospheric Model (NICAM), a cloud resolving model and shows a one week period.

(Source and description here

Imagine how much care and work has gone into building these virtual worlds. Now imagine the ridiculous notion of building these while artificially ensuring that no matter what else, they will scare the world into ceding control of our lives to the UN. There is no line of code in there that says IF CO2 > 450 THEN Fry(world).

illconsidered Thu, 07/16/2009 - 02:29

Tags

Those are great videos, thanks for digging those up.

The level of confusion over how GCMs actually work just astound me at times. For instance, from WUWT we have today:

Nothing in current climatology considers irregular flows of energy between sea and air and between air and space underpinned by another level of irregularity in solar input. The models currently work backwards from meteorolgical observations rather than forward from measurements of net energy flow in and out of the different sections (oceans and air) of the system.

What does this person think the "C" in "GCM" means, if not "coupling" in the sense of modeling "net energy flow in and out of the different sections (oceans and air) of the system", with the physics in the model being driven by observation and theoretical work to explain the observations?

In my early days as a climate change advocate, I heard a lot of yelling about computer models, so I assumed they were just "okay" and that the other threads of evidence were more reliable.

But then I saw this video - http://www.youtube.com/watch?v=D6Un69RMNSw

It's like James Hansen had a time machine or something.

I'd love you guys to come check out my blog about climate change in the scientific world compared to the popular press. Link on my name, or go to ClimateSight.org

Thanks.

@2: The original acronym expansion of GCM is "General Circulation Model". The earliest had no radiation and little or no energy flow (condensation, for instance, was absent). They served to get us started with understanding the dynamics (circulation) of the atmosphere.

Then, for decades, and to the present if you look to the right authors (probably), GCM = atmospheric model. i.e., add radiative inputs, condensation/evaporation, and such to the atmospheric circulation model. Ocean was a swamp; it supplied water to the atmosphere, and was a heat source/sink, but the water never moved. The only degree of oceanography involved was to decide whether this swamp was 25 or 50 (or whatever) meters thick.

The quote you respond to, on the other hand, could not have been written by anybody even vaguely aware of how climate modeling is done, or has been at any time in at least the last 40 years.

Watch out, the top video features weather. Soon there will be a "Models don't predict weather 100% right therefore don't predict long term trends right!!!11!!1" post.

The original acronym expansion of GCM is "General Circulation Model".

Oops, thanks. I was confusing that with the HadCM[n] - where the C does stand for "Coupled".

Ocean was a swamp; it supplied water to the atmosphere, and was a heat source/sink, but the water never moved.

From what little I've read of HadCM4 (and I guess 3) the ocean model used is a dynamic, gridded one nowadays, but since the ocean changes relatively slowly they use observed local ocean temperature data rather than the dynamic model when using the atmospheric half for weather forecasting in the UK. I had a great link to HadCM documentation about a month ago but lost it, wish I hadn't.

Reading the GISS Model E documentation, they have several models that can be used.

One is the simplified kind you mention above, with the actual surface temps modified periodically during the model run from files of observed data.

On the other hand the GISS Dynamic ocean model is a complex, gridded dynamic model. I find the way they get around the fact that some straits connecting oceans are too small to be resolved by the grid system interesting:

The model contains up to 12 variable depth subgrid scale straits which contect ocean grid boxes, which would not be connected at the resolution used. In particular, the Straits of Gibraltar, Hormuz, and Nares straits are so modelled

I assume the coupled model is run with one ocean model or another based on what research questions are being explored, as clearly the dynamic model will run much more slowly than the "change the temp array via datafile" one.

Allow us to politely disagree with the straw man in this article at TheChillingEffect.org. We think science is our best bet but these models are not working -- and it's not necessarily that they have to have been corrupted from malice on the part of modelers.

Allow us to politely disagree with the straw man in this article at TheChillingEffect.org. We think science is our best bet but these models are not working

Well, yes, but the paper you cite shows the opposite of a "chilling effect". Rather, it suggests that climate sensitivy might be *underestimated* by models by a factor of two. That it might be 5-6C rather than the current best estimate, 3C.

Mounting evidence that CO2-forced warming is WORSE than we currently believe is, through a form of mental gymnastics that is incomprehensible to knowledgable people, twisted into an argument that CO2-forced warming doesn't exist at all.

On your site you ask

Could those dire predictions of global warming be wrong?

The answer, if the paper you've fallen head-over-heels in love with is correct, is "yes, they're wrong. It's going to be twice as bad as we think".

Ta-ta and cheers, old boy.

I'd agree you can't infer too much from the models.

This is a bit more mundanely due to the chaotic behavior of Navier-Stokes. But also the nature of the solvers used for numeric simulation which are themselves chaotically-inclined, starting with Newton-difference routines, which are about as simple and straight forward as one can get. And when they aren't chaotic they are accumulating error like an SOB over the long haul!

There are no other areas of science or engineering where these same numerical simulation algorithms can miraculously go long periods of time into the future without going wrong - they can't here either. The trick used to avoid error is to not extrapolate in time very far.

When I hear "the simulation proves X" I get nervous because no one should never be that comfortable with the output of a computer simulation. I know simulations in 0D, 1D, 2D and 3D well enough to have seen them badly misused by naively generalizing the result.

The fidelity of the model is so utterly critical to the result - it always needs to be minimally physics-based and proven to have all the critical effects. Numerical simulation codes are excellent error amplifiers: you can take a small error or mistake and multiply it up far faster than a hand calculation ever could. Things like omitting cloud albedo, which has incredible sensitive effect, and then making politically charged claims and predictions are unconscionable wrong.

In engineering only fools believe the simulation is truth first, second or third time around - you can kill people by doing that. Yes, there are more than enough engineers who are such fools.

Here we're dealing with physical time constants that are beyond human intuitive comprehension - this makes using intuitive a dangerous thing if not tempered by extreme rigor. Politics is utterly without rigor and is based on a good deal of intuition. This is what makes politicization of Global Warming very, very dangerous. People get sloppy on both sides of the political argument.

And yes. I've generally not seen evidence in the arguments that most climatologist understand the numerical simulation limitations they are using.

Things like omitting cloud albedo...

Bzzzt. Wrong.

If you don't understand what you're criticizing, those who do understand ain't going to pay much attention to you.

Just sayin'

Ctrl+F: "Convection"

No results found.

Climate models fail!

Ctrl+F: "Convection"

No results found.

Climate models fail!

Bzzzt

dhogaza, you write "The answer, if the paper you've fallen head-over-heels in love with is correct, is "yes, they're wrong. It's going to be twice as bad as we think"

Actually, we haven't fallen in love with any particular paper. We do prefer a more sensible take on the world than throwing away scarce economic resources for the unlikely event of catastrophic global warming.

You are certainly entitled to your beliefs, though it seems difficult to support the notion that climate models are correct precisely because they've actually *underestimated* the negative impact. Incorrect is incorrect. Accepting a fault as evidence of success is a phenomenon seen in cults, not in solid science.

You are certainly entitled to your beliefs, though it seems difficult to support the notion that climate models are correct precisely because they've actually *underestimated* the negative impact.

No one argues that they're correct - the old saw about being useful holds, here.

Accepting a fault as evidence of success is a phenomenon seen in cults, not in solid science.

1. This is one paper, which may or may not hold up to scrutiny.

2. If it's right, then this:

We do prefer a more sensible take on the world than throwing away scarce economic resources for the unlikely event of catastrophic global warming.

is an incredibly stupid thing to say, because it means that things are going to be much worse than is currently thought.

Incorrect is incorrect.

Actually, the authors of this paper are arguing that the models are *incomplete*. Not "incorrect" in the sense that the physics being modeled are wrong, or the model implementation wrong.

Specifically, they're suggesting the models are incomplete because they don't include the impact of increased methane in the atmosphere due to the melting of clathrates from permafrost.

This is an *additive* effect to what's already being modeled. That means the number for CO2 sensitivity can only go one direction if the authors are correct - UP.

Your argument that a paper stating "things are worse than we believe" suggests "we should do nothing" is breathtaking.

As to why models don't include the impacts of increased methane from the melting of clathrates frozen in permafrost ...

The models are *conservative*. They model what's known, rather than speculation, and thus far the proposal that permafrost melting will lead to a surge in atmospheric methane has been speculative.

This paper you cite adds evidence that the speculation might be correct.

Atmospheric methane recently increased for the first time in (IIRC) a decade, also evidence that the speculation might be correct.

There are reports of direct measurements in Siberia that would be evidence that the speculation might be correct.

When or if the speculation becomes accepted as real, and can be quantified in relationship to temperature in the arctic, *then* the models will take this into account.

Not before.

The fact that modelers are conservative as to what they include isn't a "fault". it's the sound, scientific way to do models.

Regardless, there are two possible outcomes:

1. permafrost melt won't progress rapidly enough to cause methane to be added to the atmosphere in large amounts in the time frame we're currently mostly interested in (now until 2100). In this case, the model outputs of CO2 sensitivity in the 2C-4.5C range are right.

2. permafrost melting will be more aggressive than thought. In this cause, additional methane will be added to the atmosphere and model outputs of CO2 sensitivity will rise accordingly.

Either way, the current accepted figure for CO2 remains a LOWER BOUND.

"No one argues that they're correct..." and then quibble with "incorrect is incorrect"? Interesting. Thanks for helping me make my point.

Incomplete does not have to be, but can be, incorrect. However, incomplete in one area means there's no reason to suspect it is fully complete in another. To assume that there is only one problem with models is to assume a greater degree of scientific wherewithal than we currently enjoy, but to each his own assumptions.

The logic of refusing to act based on troubled models -- whether they are incorrect to the upside or downside -- is fairly apparent to those who prefer common sense and rational economic behavior.

Those demanding rush to action on climate change rarely seek rational policy and frequently prefer immediate action of any kind, even if it causes greater long-term suffering. Many feel the need to "do something" even if something is worse than nothing. Indeed, even those most accredited scientists investing in anthropogenic global warming recognize that catastrophe is a possible, but not guaranteed outcome. The economic consequences of rash policy, though, have a negative guaranteed outcome.

Judging by the way your converse with commenters here and elsewhere on the net, I don't suppose I could convince you of much. And that's cool. I do think your behavior helps convince more people to listen to me, though, and for that I thank you.

"No one argues that they're correct..." and then quibble with "incorrect is incorrect"? Interesting. Thanks for helping me make my point.

No model is "correct" in any absolute sense, that's a given. Yet, many are useful, as the old saw goes.

The primitive model used to evaluate "gun" designs for fission weapons during the Manhattan project were extremely primitive by today's standards - the "computers" who executed them were *people* pulling handles on mechanical calculators.

Yet, the model results were so robust that

1. They didn't bother testing the uranium "gun" design. Only one - "little boy" was built, and dropped on Hiroshima. From model results, the physicists knew that the only thing that would keep it from blowing up would be a mechanical failure of some sort. Not the modeled physics.

2. They didn't bother testing any plutonium "gun" design. Model results made it clear that a plutonium "gun" design could not be made to work.

"Incorrect" - in the sense of incomplete, just as climate models are today - but *useful*.

Same was true of the somewhat more sophisticated models used to design the first hydrogen bombs. By then (1950ish) there were early computers available. Modeling results showed that Teller's first design could not possibly work. By the time of the Mike shot, modeling had convinced researchers the bomb would work. Instrumentation was used to gather experimental results to fine-tune the models - fusion being rather hard to do in the lab, modeling totally led the way until real data from a real hydrogen bomb could be gathered.

Now, modeling wasn't the only thing going on, there were experiments to establish basic parameters regarding the physics, etc. Same is true with climate models, though, there's constant physics work going on which leads to improvements in the models.

Incomplete does not have to be, but can be, incorrect.

Handwaving on your part won't convince anyone, though. If you think the models implement physics incorrectly, or that the physics in the models are incorrect, the source to GISS Model E is online and you're free to *prove* your point rather than make handwaving assertions.

However, incomplete in one area means there's no reason to suspect it is fully complete in another.">However, incomplete in one area means there's no reason to suspect it is fully complete in another.

Modelers are very clear on the fact that modeling of clouds is incomplete. Regardless, given that the source to GISS Model E is online, there's no need to speculate as to where it is, or is not, complete. It's right there for you to look at.

I do think your behavior helps convince more people to listen to me, though, and for that I thank you.

People who are convinced by handwaving arguments typically have already made up their minds.

Fact is, thus far you've shown no understanding of how models work, what they might get right, what they might get wrong.

Your argument boils down to: OK, here's a paper that suggests models are wrong by a factor of 2, that climate sensitivity to CO2 is far higher than computed. Therefore, society should act as though CO2 is not a problem.

Dumb. Just ... dumb.

Thousands of lives depend upon the accuracy of models daily. Cruise ships, fishing boats, NASA launches, the Air Force and Navy and others depend on these models to report accurately. To dismiss models completely is a naive and ignorant choice.

Not all models are made the same, however. Most use real weather observations to correct their forecasts as time progresses, some don't and are purely theoretical and statistical. Then, there are boundary conditions. What happens when the location of interest is at the edge of the model? In most models that I've seen, the boundary region produces inaccurate predictions.

Finally, there's the issue of resolution. You can't use a global model to predict the weather in your city. You can't use a 48hr forecast to predict at exactly what time it will start raining.

The idea behind forecasts and models is to look for trends and apply those patterns to your real experiences. If you've noticed that the lake in your town is getting lower year after year, and the climate models tell you it's going to continue to get warmer, you can expect that your lake will eventually dry up. Hundreds of lakes in Minnesota have disappeared in the past 20 years, and I expect many more to go away in the next 20 years.

Paul,

I concur on the usefulness of models and the importance of examining real-world events. That's why models have been problematic for global warming, which has taken a decade-long hiatus.

"Dumb. Just ... dumb." Interesting way to convince others you're correct. I assume you're a hit at parties.

I've not claimed to be an expert on models, but I have addressed the logic used in the post above (which you have meticulously failed to address), the costs of just "doing something" (which you have generally failed to address), and your overzealous defense of inadequate models.

Think models are great but can be improved? That's a logical position. Your seemingly endless love affair with imperfection -- which, if used to drive policy will be costly -- is less logical.

You may invest as much as you like the validity of models. You may convince yourself of your righteousness. But data -- incomplete or incorrect -- without the application of real-world decisions on cost/benefit are essentially meaningless at best or misguided at worst.

That's why models have been problematic for global warming, which has taken a decade-long hiatus.

Not really

(you meant to say ELEVEN years, you're supposed to cherry-pick to include the super El NiÃ±o year of 1998)

Your seemingly endless love affair with imperfection -- which, if used to drive policy will be costly -- is less logical.

All models are imperfect. To say that one can't do anything based on models unless they're perfect is to say that models can't be used, ever.

You've heard of the nuclear test ban treaty, right? Since we can't test weapons any more ... guess what's used?

Why pick on climate models? I know! I know! Because you don't like the political implications that you fear will follow once our political leadership has figured out that climate scientists aren't really fraudulent green-helicopter flying commies after all.

But data -- incomplete or incorrect -- without the application of real-world decisions on cost/benefit are essentially meaningless at best or misguided at worst.

Ahhh ... the classic denialist goal-post move. Now it's "cost/benefit analysis" ... now where did I say such analysis is a bad idea? Or mention it at all?

I should state right upfront that I don't particularly enjoy wading in on climate change debates, since I am not exactly qualified to debate the issues, but there does seem to be a large and quite frankly scary misrepresentation of the science behind these models. Having sat through enough seminars and lectures on the issue (I'm right around the corner from the Center for Atmospheric Science at Cambridge), the thing almost everyone fails to mention is the HUGE error margin on these models. And I do mean huge. As in, if you select slightly different parameters, the earth enters an ice age.

I realise this debate is important, and the results are potentially catastrophic, but the climate change debate is quite possibly the worst poster child for proper science I can think of. We are dealing with a massively complex system, which we can't perform controlled experiments on, and our best predictions are based around simulations with unimaginable numbers of interrelated variables. Even in situations where we can perform experiments, the system is governed by simple equations and there is abundant data to generalize from, our simulations are poor. I speak primarily as a chemist; numerical modelling of chemical behaviour is a comparatively simple problem, yet we still pretty much keep tweaking the parameters of the simulation until it gives us what has happened in the past. I'll admit you have to publish papers somehow, but it doesn't make for great science.

My problem throughout this is not that the models are right or wrong, but that they are misrepresented. Real science deals with uncertainty. You investigate a problem, build a model, test it, report where it succeeded, and most importantly where it went wrong. Science is built on falsifiability, not confirmation. You give an indication as to the likelihood that the models are correct, but over-representing the power of the model is bordering on misconduct. Sadly, people who should know better bow to political pressure to make a judgement one way or the other. The IPCC (in earlier reports at least), instead of making a nuanced judgement and report, stating that while global warming is the most likely outcome of the model, the conclusions are not solid, instead adopts a political position of almost certainty. Admittedly recently it's been a bit more subtle, but even so, you don't really hear about that on the news - "climate change a possibility" is not something a journalist wants to hear.

The correct way to test these models is to make a prediction, and then test them. Testing on previous data doesn't count - you can just fiddle the parameters until they fit. Note that this fiddling is often unconscious; you make your model, and if it doesn't fit, you leave it and try another. If it does fit, you have no need to tweak it. Richard Feynmann famously said that the easiest person to fool is yourself; once you've made sure that you're doing good science, not fooling other people is a simple matter of honesty. Unfortunately, too few people check themselves in this way, and these tests take time. They're hard, and you don't publish many papers while you're waiting for results. Consequently, the debate is shaped by those less honest members of the academic community, who publish anyway. As I said, hardly a poster child for good science. The worst thing is, of course, if global warming doesn't occur, one side will say it was because it wasn't real, and the other will say it's because we took steps to avert it. We won't have actually learned anything.

My problem throughout this is not that the models are right or wrong, but that they are misrepresented. Real science deals with uncertainty

You mean like this? "Climate sensitivity to a doubling of CO2 is in the range 2C-4.5C"?

over-representing the power of the model is bordering on misconduct.

Consequently, the debate is shaped by those less honest members of the academic community, who publish anyway. As I said, hardly a poster child for good science.

Oh oh ... another accusation of science fraud. Ad hom on the field at large.

Tch tch.

I saw exactly these same words on another site recently ... hmmm ...

The worst thing is, of course, if global warming doesn't occur

It already *has* occurred. And *is* occurring. By the end of '09, 9 of the ten warmest years on record will have been in the 21st century. How people label this as "evidence of global cooling" is beyond me.

The correct way to test these models is to make a prediction, and then test them.

Which, of course, has been done. For someone who claims to know so much, you seem to know little.

Testing on previous data doesn't count - you can just fiddle the parameters until they fit. Note that this fiddling is often unconscious; you make your model, and if it doesn't fit, you leave it and try another. If it does fit, you have no need to tweak it.

Someone else who doesn't understand how GCMs work. They're not statistical models juggled to fit past data.

massive_hair,

The correct way to test these models is to make a prediction, and then test them.

This goes on all the time using various things, eg large volcanic eruptions or some previously unobserved aspects of the climate system like radiation at the TOA (top of the atmosphere). Read more about models and tested predictions here and here.

If however you mean we need make a thirty year projection and then wait, this is not a realistic option.

Testing on previous data doesn't count

What is this, some kind of collegiate sporting event? There is no reason to exclude using hindcasts to test models and every reason to do so. The past is an excellent source of test data involving all kinds of very different climates and climate changes.

Unfortunately the rest of your comment is a confusion of journalism criticisms and actual research with no acknowledgement of the difference that it can not be untangled enough to be answered. Your statement "everyone fails to mention is the HUGE error margin on these models. And I do mean huge. As in, if you select slightly different parameters, the earth enters an ice age." is both wrong and confused. No papers are published without uncertaintiies. And your assertion about entering an ice age, if true, would imply great sensitivity, not great uncertainty.

You should fix the initial problem you identified ("I am not exactly qualified to debate the issues") by asking questions rather than opining at such great length!

How come no one will address the basic logical error in this post, which is that criticism of climate models -- even if you think that the critic is "dumb" -- must be wrong since so much work goes into models? A ton of work can go into building bridges, and unfortunately sometimes they have structural problems.

Personally, I would have just chocked it up to a hasty blog post -- everyone does it and there's no shame in wishing to take a mulligan.

But the defensiveness shown in the comments is telling. Does the average scientist become irate if he thinks a neanderthal misunderstands gravity? If one is so convinced that their position is scientifically valid, there is no reason for such hostility. It is usually when one's religious beliefs are under attack that such reactions are seen.

... and still no one has addressed the simple logical error of this post. Coby and dhogaza may be in good supply of confidence -- and, perhaps even a good supply of knowledge -- but appear lacking in grace and logic.

How come no one will address the basic logical error in this post

A second moving of the goalposts.

even if you think that the critic is "dumb"

I don't think you're dumb, indeed, when defeated on a point, moving the goalposts is smart.

Because it's your only hope of maintaining any semblance of credibility.

Boy, didn't take long to break you down from your triumph claims of victory into being a goal-post moving troll, did it?

Does the average scientist become irate if he thinks a neanderthal misunderstands gravity?

Glad you identify with the neanderthals. But ... no, the average scientist gets irate when the neanderthal tells him that the *scientist* misunderstands gravity. And when, even after repeated references to the success of ballistic tables to guide accurate cannon shots that destroys the neanderthal's village, the neanderthal *still* says the scientist doesn't understand gravity. While digging his own wife and children from under rubble.

Thanks for the analogy, it's entirely fitting.

How come no one will address the basic logical error in this post, which is that criticism of climate models -- even if you think that the critic is "dumb" -- must be wrong since so much work goes into models?

This statement is, of course, a lie.

Coby didn't say criticism of climate models is wrong because so much work goes into them.

He says this:

There is no line of code in there that says IF CO2 > 450 THEN Fry(world).

In other words the typical, widely-stated, accepted-by-denialist shits, complaint that the climates "assume" global warming is total bullshit. In other words, that ignorant, dumb criticism based on having no idea as to how they work is bullshit.

He's right. He could've worded it better so liars like you couldn't intentionally "misunderstand" his statement, but it's not his fault that you choose to lie.

Oh, and it might be nice if model critics spent even 0.001% of the time understanding models vs. the time spent building them. Because criticizing them based on total misunderstanding of how they work is totally unscientific.

Indeed, one might suspect it's ideological ... and I suspect that, of you.

Coby,

Re your post #26, Could I ask you one simple question - can you put a figure on how certain you are that the recent global warming is due to anthropogenic CO2?

Good supply of knowledge? Yes
Good supply of logic? Yes

The only one you might be anything near right on is grace. And, hell, having to answer the same denialist bollocks over and over again, and having them repeat the same argument as if no one had said anything, is incredibly frustrating.

If one is so convinced that their position is scientifically valid, there is no reason for such hostility. It is usually when one's religious beliefs are under attack that such reactions are seen.

Actually, this type of reaction is fairly typical when it comes to dealing with denialists. You see the same hostility directed to evolution deniers, AIDs denialists, holocaust denialists, and justifiably so.

Richard, the IPCC is 90% certain. I think they are being cautious and conservative and are afraid to overstate the case. I am personally 99% certain that the recent global warming of between .1 and .2 oC per decade is primarily caused by anthropogenic factors, foremost of which is CO2 emissions. You should prefer their conclusion over mine, as I am not an expert.

Bret, perhaps you are unaware of the very vapid criticisms of climate models that are out there, especially the continuous insinuations that they are simplistic contrivances designed solely to show increased CO2 will cause severe warming. This post is offered to address those arguments only. I put a little bit more thought into defending model results on the two pages I linked to in comment 26.

Unsophisticated arguments don't require sophisticated debunking.

Notwithstanding the above, yes of course you are right that the fact they are complex does not mean they are above criticism.

Can you acknowledge one or two of dhogaza's points rather than changing the subject? I am specifically interested in whether or not you accept that a paper saying there is evidence the models are underestimating the climate's response to CO2 by half (your offering) is not a compelling reason to conclude we should just continue as we are til the models get better.

Coby,

You say "the IPCC is 90% certain. I think they are being cautious and conservative and are afraid to overstate the case. I am personally 99% certain that the recent global warming of between .1 and .2 oC per decade is primarily caused by anthropogenic factors, foremost of which is CO2 emissions. You should prefer their conclusion over mine, as I am not an expert."

Why should I accept either of these conclusions? Neither of these opinions are founded on science. The IPCC's conclusion is purely political, and yours purely based on faith.

Can you show me in the scientific or technical analysis of the IPCC HOW THEY HAVE ARRIVED AT THIS FIGURE?

The technical report of the IPCC 2001 has this to say when it examines the question of "WHETHER A HUMAN INFLUENCE ON CLIMATE CHANGE TO DATE CAN BE IDENTIFIED.":

"The SAR concluded that âTHE BALANCE OF EVIDENCE SUGGESTS THAT THERE IS A DISCERNIBLE HUMAN INFLUENCE ON GLOBAL CLIMATEâ. It noted that THE DETECTION AND ATTRIBUTION OF ANTHROPOGENIC CLIMATE CHANGE SIGNALS WILL BE ACCOMPLISHED THROUGH A GRADUAL ACCUMULATION OF EVIDENCE. THE SAR ALSO NOTED UNCERTAINTIES IN A NUMBER OF FACTORS, INCLUDING INTERNAL VARIABILITY AND THE MAGNITUDE AND PATTERNS OF FORCING AND RESPONSE, WHICH PREVENTED THEM FROM DRAWING A STRONGER CONCLUSION."

The most important thing in my mind in the above is the uncertainties that the IPCC admits in THE RESPONSE to these forcings, which I believe from the evidence is to mitigate and offset the effects, in other words a negative feedback, as the climate has always behaved in the past.

When there are a large number of uncertainties, which there are in climate models, as you are probably aware the uncertainties are multiplied with each other so that the end result is even less uncertainty and not more.

Nothing in the technical analysis suggests a 90% certainty and most importantly nowhere have they shown a working on how they have arrived at that certainty.

nowhere have they shown a working on how they have arrived at that certainty

Am at a loss as to how to answer this, the entire report is how they have arrived at that conclusion! It is a ridiculous question.

You should read it, start with the summary for policy makers (large PDF) and you might want to focus on the section about attribution(large PDF).

As an unqualified general statement this is false. Multiple, independent uncertainties can in fact work to constrain each other. Consider multiple independent measurements of the same property as a simple example. If your uncertainty on each measurement is 10%, 100 measurements will get you a much more constrained range of values, not less. Likewise, if you have a number of uncertain factors, but you know they must add up to 100%, you can actually reduce some of the individual uncertainties.

The IPCC's conclusion is purely political, and yours purely based on faith.

The IPCC is a political body, but its assessment is a scientific one and has been reviewed by national academies and scientific bodies all over the world. With the exception of a more lukewarm statement from the American Association of Petroleum Geologists, all of this various scientific bodies concur with the IPCC's conclusion.

You are not obligated to accept their or my conclusion, but both are based on the scientific evidence. Considering all the evidence I have compiled on this site, agree with it or not, your dismissal of my opinion as purely faith based is much more a reflection of you than it is of me.

Coby -
"Am at a loss as to how to answer this, the entire report is how they have arrived at that conclusion!"

I will accept that you are at a loss as to how to answer the question. But to tell me to read the whole report is a cop out.

Certainty or uncertainty is a mathematical computation. Where exactly have they worked this out? Or even claimed to have worked this out? You have given explanations of various questions on your website. Give one on this also, or admit frankly that there is none.

Richard,

Try following Coby's link. That's where I found this, which explains how the IPCC defines its probability estimates.

The IPCC in part calculate certainty quantitatively where possible and estimate it with expert opinion elsewhere.

You say:

"The IPCC's conclusion is purely political, and yours purely based on faith."

That's an unfounded slur. At least, it seems to be, given that you provide no supporting evidence.

You also provide a quote referencing the TAR which discusses the previous IPCC report, the SAR, and conclude that this says something about our current state of knowledge. There are two things wrong with this:

1. The reference you quote in the TAR to the SAR speaks nothing of the TAR's conclusions.

2. Why are you quoting the TAR when we've got 4AR? Which, btw, states the following with regard to attribution of greenhouse gas forcing:

"Most of the observed increase in global average
temperatures since the mid-20th century is very
likely due to the observed increase in anthropogenic
greenhouse gas concentrations."

If you disagree with this certainty estimate perhaps you should explain why? It's not clear to me why anyone would think this statement is false.

Paul H,

Thank you for your comments.

When I said "The IPCC's conclusion is purely political, and yours purely based on faith.", I did not mean it as a slur on Coby and I stand by the statement that the IPCC's conclusion is purely political.

Their conclusions are always political vetted line by line by the political bosses of the IPCC.

But this is not the only reason why I say this.

In the link you sent me, (which are Guidance Notes for the Lead Authors of the IPCC), on making expert judgements they have advised: âBe prepared to make expert judgments AND EXPLAIN THOSE BY PROVIDING A TRACEABLE ACCOUNT OF THE STEPS USED TO ARRIVE AT ESTIMATES OF UNCERTAINTY OR CONFIDENCE FOR KEY FINDINGSâ

No where have they explained their key finding that global average temperatures have "very likely" increased due to increase in anthropogenic greenhouse gasses, much less provided a traceable account of the steps by which they have reached this conclusion.

As for Coby's belief - I think it is mistaken, and hence ultimately founded on faith rather than science.

The document I linked to expresses how the IPCC scientists use evidence to arrive at conclusions of differing certainty. If you read the IPCC chapter on attribution the evidence is laid out in a manner which enables you to see how they reach the conclusion we are discussing.

e.g. the document says "Be prepared to make expert judgments and explain those by providing a traceable account of the steps used
to arrive at estimates of uncertainty or confidence for key findings â e.g. an agreed hierarchy of information,
standards of evidence applied, approaches to combining or reconciling multiple lines of evidence, and
explanation of critical factors."

It's clear to me, at least, that chapter 9 carries this out when attributing late 20th C warming to GHG increases and other sources of RF. For instance, they indicate that the consistency of conclusion from multiple independent lines of evidence creates a robust overall conclusion with regard to GHG radiative forcing attribution i.e. in the IPCC's language, a series of conclusions derived from independent sources, indicating the same overall conclusion, with more limited certainty (only likely), add up to robust conclusion with high certainty. The chances of all of these lines of evidence being flawed is very low. If you only read part of it, read the summary 9.7, which is a great example of this method in action. Now you know that this statement is derived from the certainty placed on the interpretation of other lines of evidence why don't you look at how those conclusions are reached. It's explained in detail in this chapter.

As a matter of fact:

1) The 19-page AR4 IPCC SPM is a political document, since it has to be agreed on, sentence-by-sentence by all governments, including for example, the USA, Russia, and Saudi Arabia.

That tends to water down the conclusions. Actually, it's pretty amazing that anything gets through, especially when one talks to the scientists who participate.

2) Of course, that is why the *scientists* write not only the full reports, but for each a Technical Summary, which for WG I is 73 pages, or one can go to the full report, which is ~900 pages, or the peer-reviewed references, which are vast. They even do a pretty good job of introductory material (FAQ's, boxes). Even the TS alone ought to answer most rational people's questions.

3) Coby is quite right.

It seems to have been forgotten that chaos theory got its (recent) start through the problem of climate modeling. Tiny disturbances can have huge effects.

In addition, if the models are run backward, do they "predict" the past well over the last, say, 100 years?

It seems to have been forgotten that chaos theory got its (recent) start through the problem of climate modeling.

Sigh ... the confusion of weather with climate extends even to this?

"An early pioneer of the theory was Edward Lorenz whose interest in chaos came about accidentally through his work on weather prediction in 1961.[37] Lorenz was using a simple digital computer, a Royal McBee LGP-30, to run his weather simulation. He wanted to see a sequence of data again and to save time he started the simulation in the middle of its course. He was able to do this by entering a printout of the data corresponding to conditions in the middle of his simulation which he had calculated last time."

See? Weather prediction, not climate modeling.

We can make many, many climate prediction like ... this January in Portland, Oregon will be on average colder than next July. Even though I can't predict the weather for each day in either month.

In addition, if the models are run backward, do they "predict" the past well over the last, say, 100 years?

Someone doesn't understand how models work. You don't run them backwards.

However some models do a pretty good job of hindcasting not only in the recent past but various paleoclimate scenarios, too.

Breaking news from Marc Morano

illconsidered — Tue, 07 Jul 2009 12:24:58 +0000

Breaking news from Marc Morano

Marc Morono (sick) breathlessly announces that Gavin Schmidt has finally admitted that weather is chaotic and GCMs can not model it.

And yes, that is about as shocking an admission as water is wet.

Here is the incriminating quote:

"The problem with climate prediction and projections going out to 2030 and 2050 is that we don't anticipate that they can be tested in the way you can test a weather forecast. It takes about 20 years to evaluate because there is so much unforced variability in the system which we can't predict -- the chaotic component of the climate system -- which is not predictable beyond two weeks, even theoretically. That is something that we can't really get a handle on,"

Pretty shocking, eh? Climate models can not predict short term natural variability (aka weather).

But wait, I thought the (statistically nonexistent) short term stasis in warming was a failed model prediction. Denialist cake is the best, the more you eat it, the more of it you have.

Or something....

illconsidered Tue, 07/07/2009 - 08:24

Tags

and don't forget water is a pollutant!
Thanks for a good laugh. Morano gets far more attention than he deserves though...

Dan

It's not the ignorance of people like this that bothers me, it's the willfulness of the ignorance. If he actually tried to understand what Gavin Schmidt was telling him, he might learn something. But no.

Morano aside, that was an interesting (the actual interview) read. Thanks for pointing it out.

Wow, I actually had no idea that Gavin Schmidt is English. Whoops!

...ok, so this person is not the poster child for an intelligent conversation. Does this change the fact that current climate models CAN'T be checked with real data? Or that there isn't a 'control' regime from which to extract a truly background-free CO2 signal in the global mean temperature?

You guys should sure-up your argument a bit before picking on those you see beneath you.

Aaron:
"Does this change the fact that current climate models CAN'T be checked with real data?"

This is not a fact.

"Or that there isn't a 'control' regime from which to extract a truly background-free CO2 signal in the global mean temperature?"

You mean like another earth to play around with?

How is it not a fact that the climate in 2050, as being modeled today, can be checked with real data? As far as I can tell, my physics department has not mastered the science of time travel. Please let me know if your department has. The only period of complete data is the past 20 years or so. Some of that data agrees with models, but it's hard to say why it agrees. It is a several thousand parameter model for a 9 or 10 order of magnitude larger parameter space. It's not hard to press the right buttons when the wrongs ones aren't in your model.

As far as 'control' goes, yes, it would be nice to have another earth to goof around with. It's so nice that every other scientific field uses such a 'control'. The vast majority of global mean temperature signal is 'flooded' by CO2 since the industrial revolution. So how to we deconvolute the CO2 signal if we can't control for it?

The answer from your other posts seems to be 'well, science is hard' which is true, but completely off the point. If it is indeed so hard to find such a signal, and in infinitely simpler systems it can be, why make the argument that it's importance relative to other contributions (solar flux, el nino, cloud cover, etc.) is undeniable? It's a very poorly constructed scientific argument to say the least.

What seems to be the most baseless aspect of this and many other arguments for policy change in the US and elsewhere is the importance of models. Well, the over importance of them really. Models for different scientific systems are used in every field, but in all of them one still needs to verify predictions with real data. 20 or 30 years worth of suitable data doesn't cut the mustard to predict 50 or 100 years into the future. Especially since one cannot parse out the true contribution of CO2 to the global mean temperature signal from 'the noise'.

How is it not a fact that the climate in 2050, as being modeled today, can be checked with real data? As far as I can tell, my physics department has not mastered the science of time travel.

It's called "paleoclimatology", and models do a good job of recreating much of what we know about it.

Aaron:

"How is it not a fact that the climate in 2050, as being modeled today, can be checked with real data?"

Sorry, this is not what you said at all. However, this new statement is certainly true. The best way to test current models is by hind casting and comparing modeled results with actual measurements. Hind casts of the 20th century are very successful for the crude indicators like global temperature averages. There are many other features of modeled climate that can be compared with actual observations, such as diurnal cycles, lapse rates, stratospheric temperatures, seasonal cycles, response to large volcanic eruptions, major ocean currents and precipitation patterns. These are the kinds of tests I was thinking of when I disagreed with your very general dismissal of testing climate models.

"As far as 'control' goes, yes, it would be nice to have another earth to goof around with. It's so nice that every other scientific field uses such a 'control'."

Sure, "every scientific field". Evolutionary biology, cosmology, geophysics etc, etc... They all have control systems to play around with. I don't think so.

"The vast majority of global mean temperature signal is 'flooded' by CO2 since the industrial revolution. So how to we deconvolute the CO2 signal if we can't control for it?"

The only way is through modeling. If you reject the concept of modeling then you do not have the first most basic grasp of what science is. No one says it's easy and no one says our understanding is complete, but you need to come up with much more informed objections that demonstrate a grasp of what is understood if you want to be taken very seriously.

Climate models do not have to be very complex to be generally informative. You should check out Robert Grumbine's series on simple climate models. This is a summary post with links, though it may not include the latest articles. I also recommend Spencer Weart's History of Global Warming. This concept did not arise out of opaque and complex computer models.

"The answer from your other posts seems to be 'well, science is hard' which is true, but completely off the point. If it is indeed so hard to find such a signal, and in infinitely simpler systems it can be, why make the argument that it's importance relative to other contributions (solar flux, el nino, cloud cover, etc.) is undeniable? It's a very poorly constructed scientific argument to say the least."

Well, I do not recall making the argument that it is simply undeniable on its face that other influences are dominating. However, massive amounts of hard work have in fact been done, and the only persistent arguments out there are in fact no more than pure denial. There is certainly the possiblity of new dramatic findings overturning some very basic conclusions, but at this stage it is vanishingly unlikely that the current climate change is not anthropogenic.

"What seems to be the most baseless aspect of this and many other arguments for policy change in the US and elsewhere is the importance of models. Well, the over importance of them really. Models for different scientific systems are used in every field, but in all of them one still needs to verify predictions with real data. 20 or 30 years worth of suitable data doesn't cut the mustard to predict 50 or 100 years into the future. Especially since one cannot parse out the true contribution of CO2 to the global mean temperature signal from 'the noise'."

If this were an abstract scientific question then I would agree we should all just keep up on the journals and wait to see if the planet warms dangerously or not, but the fact of the matter is there is a great deal at stake. Frankly, I find it hard to understand how anyone can not see that uncertainty is not your friend in determining what action to take in the face of risk. Right now, the relevant action is actually well underway: we are dramatically increasing CO2 levels. If there is great uncertainty, then this action should cease until the models are good enough to be 99% confident there is no danger. Practical concerns and political realities aside, what your argument should be advocating is a cessation of CO2 now, wait 50 years to see if the models are correct, and then decide if we can safely pump CO2 into the atmosphere or not.

Back here in reality, we have no rational choice but to judiciously chose our course of action based on the knowledge and understanding we have right now.

Thanks for the comments.

Coby,

there are a great many presumptions you make in this argument. First and foremost is that there is a great deal at stake. But there is a great deal at stake in many fields, yet we do not say 'well the scientific method should be bypassed because of the importance of this issue'. Say cancer research. Couldn't we just bypass some clinical tests and get 'experimental' drugs right into the market where we could see if they work or not? Certainly cancer is a pressing issue to humanity.

Second, if you don't know the ability of these models to predict the climate properly because you are using ill-conditioned and indirect data whose uncertainty and associated propagated errors in such climate models is poor-defined, how do you even know that there is so much at stake? Maybe there is a 1 in 100,000 chance that what you think is at stake is truly at risk. Maybe it's more. But to make such a claim as though it is a fact of some kind doesn't seem complete truthful nor is it consistent with the message you give on your other posts. If this science is truly that difficult, and I think it's even more difficult, how have we come to a point where we know what's stake without enough direct, well-conditioned and useful data?

Third, and this is the kicker, you conflate modeling with theory. There is nothing basic about modeling. It is the utilization of computer algorithms to calculate stuff. Theory is basic. It's just as basic as experiments for that matter. But modeling is not basic. It's what climate researchers do because there is little else to be done. If that were true, could we say that Newton or Einstein or Euler didn't have a form grasp of science because they didn't model physical systems?

Fourth, this whole argument boils down to 'what else can we do?' and you know what, I have no idea what else to do. But at least I admit to the uncertainty in my position. All this about so many people working hard to make it work is great and all, but it doesn't make them right. The ONLY way to test a model is with real, direct, well-conditioned and understood data. Not data that is just lying around. That's the way science is done in reality. If you would like, I can give you a tour around my lab. We'll show you how it's done...

Coby, while gratuitous snark may not advance the scientific argument, I did get a wicked chuckle out of "Marc Morono (sick)". Snap!

If that were true, could we say that Newton or Einstein or Euler didn't have a form grasp of science because they didn't model physical systems?

But they did build models. Newtonian mechanics *is* a mathematical model of how objects interact ...

The ONLY way to test a model is with real, direct, well-conditioned and understood data.

And who are you to say they don't?

The entire anti-model rant is a bit disgusting. The basic approach used by climate models is no different than the early, primitive models used in the Manhattan project and later during research into the hydrogen bomb. Modeling showed that Teller's first design for the hydrogen bomb wouldn't work. Modeling based on better physics pointed the way to the first "Super", the Mike shot. Earlier fission work depended less on models, but that had more to do with available computing power (rooms full of computers - i.e. *people* - computing on mechanical calculators, then the very first general-purpose computers) than any aversion to modeling. Today, our nuclear weapons program is entirely dependent on modeling, as we no longer test.

The way experiments are formed to test climate models varies from they way lab experiments are designed, by necessity. But experiments have been run, nonetheless.

I love it when bloggers wander into the house claiming to be know more about climate science than those working in the field, displaying ignorance right and left.

The confusion still abounds.

This is not a rant for one. Second, it's most certainly not anti-models. Models are very important for determining what happens in experiments.

But what Newton came up with is not a model.

It is a theory.

There is an inherent difference that you seem to be missing between these two concepts. There is no new theory contained in global warming research. It is the application of known theory to a particular part of a physical system. More specifically, it is the model of carbon dioxide forced increase of the global mean temperature using the laws of spectroscopy, statistical physics, atmospheric physics and thermodynamics. But this is very different from what Newton did. He made very general statements about the world around us and how those statements manifest themselves in phenomena we see. F=ma does not necessitate a model system in which to be true.

What is becoming entertaining to me is that you are making my argument for me. The example of the atomic bomb and the Manhattan project is exactly what I saying needs to be done with respect to climate research of global warming. The models proved to be useful because Fermi and others could do controlled experiments on the chain reactions that lead to an atomic explosion. Do you think they built that giant graphite neutron reactor at the University of Chicago for fun? No they did it to test the models that were being produced. They also did numerous other tests there and Los Almos. And I'm sure the models showed that taking theoretical steps in certain directions might not be fruitful, but I am also certain that just as often the models themselves didn't work. This is research we're talking about.

Climate research is inherently different in this respect. It is the application of theory to a particular model and assessing the results of the outputs of such models. What I am saying here, and you continue to be unable to refute, is that if one does not understand the uncertainty in the data used to make such assessments, how does one know if the models really work?

Such uncertainties, in the form of errors, must be properly propagated to completely understand the implications of outputs from such models. Since there is no control on the vast majority of data for this purpose, paleological or not, it is very hard to assess uncertainties. Given that, how does one come to the conclusion, scientifically, that we are playing with the fate of the world?

There seems to be a logical jump being made here that is not taken lightly in other fields but is acceptable with respect to this issue because of it's grave importance. There are two main problems with such an approach.

First, because we don't have well-conditioned data one can't completely assess the outputs of these models as true or not. This I will keep repeating until you can provide the uncertainties associated with measurements like those of CO2 from tree rings from thousands of years ago. Is it plus/minus 50, 80 or 500 ppm? It would be nice to have some sources for the calculations of such uncertainties.

Second, if the climate is as sensitive as these models would lead us to believe, then we must be extraordinarily careful with our response to warming. By not knowing exactly what is happening and simply acting on what we know now can create unforeseeable problems with more uncertainties. The analogy of the car driving in the fog near a cliff is apt, except that there are 50,000 pedals, 49,999 of them accelerate the car and only one is the brake. Are we really going to just slam on them randomly given what we know at this point?

It has also come to my attention that a very simple model has been produced, only two phases, in a paper that was published a little over a year ago. Here is the link to the pdf. The researchers show that such a climate system, very simple mind you, will display a 'memory' of the forcings. This is known as hysteresis and is how most magnets are made these days. So even if we reduce carbon in the atmosphere, the temperature might stay the same.

As for the quip about bloggers, they bother me too. It's unfortunate, however, that your comment reflects much more on your standing in the conversation than my own. As of tomorrow, I will be a PhD candidate in the Applied Physics Program at the University of Michigan.

More than that, my work is on the interaction of light with matter, which may be of some use with respect to this issue. On top of that even, Professor Marc Ross who is an environmental physicist here at UM served on my qualifying exam committee asking me several questions on this topic ranging from simple to very complex. He also told me, point blank, that is has been very, very hard for anyone to say exactly what is causing what we see in terms of warming on this planet.

It may serve you well, since your work is with computers seems to be overwhelming your take on this topic, to open your mind's eye to what some people who work with physical systems have to say. Again, I will most certainly express that there is a great deal about this that I don't understand. But the questions about data used to assess these models are very simple and you seem rather persistent in ignoring them and lambasting me as some ignorant person. That is unfortunate. It really says much more about you than me.

Mmm Aaron sounded quite reasonable (lots of big words in the correct order at least, not like some other deniers who have trouble with English syntax) till it all fell apart when he said:

"This I will keep repeating until you can provide the uncertainties associated with measurements like those of CO2 from tree rings from thousands of years ago. Is it plus/minus 50, 80 or 500 ppm? It would be nice to have some sources for the calculations of such uncertainties".

WOW, a whole new discipline, CO2 concentrations from tree rings:-) Were they found frozen in the ice cores by any chance?

Aaron:

Congratulations on becoming a PhD candidate and I trust Professor Ross is an intelligent and educated man, but if this information is offered to give authority to your views, I think we would have to defer to the expertise of these folks. Myself, I have never claimed any authority of my own, nor do I offer my own personal theories or conclusions (at least not intentionally and not on the major points). I merely try to communicate what the latest scientific information is. I don`t mind opining, I am a blogger after all, but I do insist that we get the facts straight.

You are clearly arguing from a great deal of ignorance, and therefore from a different set of "facts". I highly recommend that you get yourself familiar with the latest IPCC report. You would also do well to check out the link I offered to Weart`s history of global warming. Did you yet?

About what models are or not I must insist that you do not own the word, nor do I, and it has it own definitions independent of your or my intended meaning. I will be clear and tell you that when I say model in the comments above I mean a physical, mathematical, or logical representation of a system of entities, phenomena, or processes. I consider e = mc^2 to be a model. I am happy to revisit our modeling meta discussion above if you reread what I wrote with that definition in mind. If you wish to shift the topic to another kind of model please be specific and we can start again.

Regarding your objections to data used to feed or verify GCM`s please be specific. Exactly what data are you thinking of and exactly what is wrong with it. I have to agree with Ian that your confusion about tree rings betrays an ignorance of this material that is not well matched to the strength of your apparent convictions. The same goes for other issues you are raising, you are giving us very broad characterizations and nothing specific to examine!

(Side note: we are in the comments section here and you are dialoguing with more than one person. It is not clear to me who "you" is referring to above.)

Ian,

it is a wonderful thing when someone makes an accusation that they can neither backup nor even bother to check themselves.

You might be interested in this PNAS (that stands for Proceedings of the National Academy) article. In it the authors detail the importance of tree rings given that some species can live thousands of years (bristlecone pines et al.) There is also no discussion of uncertainties in this paper.

And all I had to do was Google "CO2 Tree Rings" to get that. Google is very useful for information. You might want to look into using it.

I would also not like to be given the moniker 'denier' seeing that at no point have I mentioned that global warming is not happening. It is most certainly happening. I merely disputing the presentation that it is scientific fact garnered from the scientific method, as applied in other fields including my own, that CO2 is the most responsible forcing. Maybe you could come up with a more fitting negative description of my position that actually reflects that reality of our situation rather than ignoring it.

Aaron Rury, please re-read that PNAS paper you quoted. I did read it and it does not say what you are claiming. The majority of the researchers who looked for a CO2 effect on tree rings did not find such a relationship. The only "scientist" who did find one was Idso. Have you ever heard of him? He is one of the more notorious "scientists" who are typical deniers. He has a web site (CO2science, but I'm sure you know that)) which is full of dishonest comment, misinformation, cherry picking and other examples of scientific malfeasance. If you don't want to be called a denier I suggest you broaden your list of sources for quality information on climate science.

I hope you are more careful and honest with your own graduate work, I would have very harsh words for anyone who reported in a thesis what you just did with that PNAS paper. That could be considered scientific misconduct but at the very least shows that you are not very careful in your interpretations of scientific results.

But what Newton came up with is not a model.

It is a theory.

it's both, and physicists know it. For another example of "both" look up "Standard Model".

Good luck correcting them ...

And, yes, I understand what was done during the Manhattan Project. The development of the hydrogen bomb was much more grounded in computer implementations of models of nuclear physics than the earlier fission bombs, but this was mostly due to the rapid increase in the speed of computation and the more limited ability to do lab experiments on fusion. Still, the models implemented and computed on mechanical calculators and later in the project when making the two fission bomb designs, very early electronic computers, were extremely useful.

Remember, they didn't bother testing Little Boy.

Also, climate scientists do run experiments using their models, you can lie about it until you're blue in the fact, but it won't make your lie true.

It may serve you well, since your work is with computers seems to be overwhelming your take on this topic, to open your mind's eye to what some people who work with physical systems have to say

I do. Atmospheric and solar physicists are very active in the climate science community. Why should I ignore them and pay attention to people who aren't specialists in the field?
Why would I expect some random applied physics prof to know more than they do? Why would I expect a freshly-minted undergraduate (you) to know more than they do?

On the seemingly-ever confusing notion of a 'model', I will say this. Equations are MATHEMATICAL models of a physical system that allows us to understand how different physical parameters affect each other. Newton's laws or Maxwell's equations are great examples of this type of model.

In science research, such mathematical models are applied to scientific models like climate models, that also use math in some contexts, but there is an inherent difference. When the laws of physics are applied to a scientific model, we already know the parametric dependencies in the physical system. We just want to know how those dependencies mean TO THAT SYSTEM IN PARTICULAR. A good example of this is the standard model, which does not necessitate new dependencies between particles other than QED, but gives us a coherent picture of how different particles can be divided up with respect to similarities and differences. So I would say that climate models are a SCIENTIFIC model as opposed to a MATHEMATICAL model, despite the fact that impressive amounts of math used in such models. Can we all agree on this assessment?

Ian,

You seem to be misunderstanding the argument the PNAS paper provides with respect to your comments. You implied that my previous comment concerning the lack of well-understood uncertainty in tree ring research was inconsequential since such research doesn't exist. The citation of the paper merely provides proof that it does exist. The fact that this particular paper is more critical of such a technique is neither here nor there. It is simply the fact that the research exists. Some researchers, not all of them can be named in such a publication, do find what they interpret as a connection between tree growth and CO2 concentrations. My simple question is, 'what's the uncertainty associated with such measurements?'. Why don't we stick to one argument at a time rather putting words in my mouth?

Coby,

I admit that it is very hard for me to keep up with all the 'data' that is used to check the output of models. The one example that comes to my mind is from chapter 6 of 'Statistical Analysis in Climate Research' where the authors discuss signal processing in general and applying such rules to the CO2 signal. You check out most of the chapter on Google scholar. But the analysis of this research points out that the big systematic problem is the lack of a true 'control' regime. In describing how researchers get around this fact, the authors point out there is no method which can be reliably applied. So I don't think it is necessary to make a table of the different data and why each one of them has issues. They all seem to have the same issue of being ill-conditioned with respect to an unknown uncertainty that is very difficult to properly propagate error in these climate models.

The fact that you bring up my 'convictions', again, I think only serves to further cloud this discussion. My simple conviction is that there should be a strict application of the scientific method to produce scientific information. That means models have a place next to theory and experiment in importance, and not above them simply because all we can do is scientifically model our climate. I have a similar skepticism of ideas like string theory although there is a community of researchers who push its importance. It just doesn't seem like science if they can't tell us experimentalists how to prove or disprove the theory's implications.

dhogaza,

Newton laws are a mathematical model. I will agree with such an idea. But climate models are SCIENTIFIC models which are, in their nature, very different from the Newtonian laws they use to 'make' data. I think you need to better appreciate this difference.

That you are willing to distrust my opinion and frame my knowledge as 'undergraduate' despite the fact I graduate 6 years ago and have done research since is not shedding the best light on your position. Also, one doesn't gain PhD candidacy right out of undergrad. Why bring up such things if you have such a strong argument? Just explain the answers to the questions I have posed. Ultimately, is the push of this plan to just destroy the reputation of those who disagree with you?