global warming: salvaging fact from heaps of BS

[Mokele]

The topic of how accurate or reliable GCM's might be is, in fact, not possible to quantify (yet), and is subject to opinion.

 

Projections made in 1988 accurately predicted the temperatures almost 20 years later, with simpler models running on computers less powerful than our cellphones.

[SkepticLance]

Mokele

 

And modern GCM's running in 2003 underestimated Arctic ice melt by a factor of 100%.

 

The reason for that underestimate was an ocean current bringing warmer water north, that had not been detected previously. It is these 'unknown unknowns' that are most likely to screw up GCM's. Slow moving ocean currents are very difficult to detect, let alone measure. Deep ocean currents are very poorly understood, and have a big impact on global climate.

 

Cloud formation is critical to climate modelling, and is very poorly understood. The impact of variabilities in this factor will be to create unpredicted outcomes.

 

As time passes, of course, GCM's will get better. As of right now, they have definite limitations.

[Mokele]

True, but limitations don't make them useless, and they definitely should not be dismissed entirely. Clearly, they have predictive value, especially for large-scale variables like average global temperature, even if they break down at smaller-resolution variables, like arctic sea-ice levels.

 

Someone whose name I forget once said "All models are wrong, but some are more useful than others." No model will ever be perfect, but they will improve over time, and many are specially tailored to particular issues.

 

Basically, don't throw the baby out with the bathwater - exercising caution about predictions is not the same as just disregarding them due to imperfections.

 

Also, a climate scientist who gave a seminar I attended pointed out that for long term (100+ year) predictions, the biggest unknown is human behavior, with regards to everything from carbon output to simple population.

 

Mokele

[scalbers]

As Skeptic Lance points out a model can just as easily underestimate global warming effects as overestimate it.

 

On another note I just read Jim Hansen's paper from this year today where he lays out the rationale for 350ppm as CO2 concentration limit. He points out that models and other estimates only take into account short-term feedbacks and ignore longer term feedbacks that would increase the effect.

 

It's also interesting to consider what time in history (and what CO2 levels) the Antarctic and Greenland icecaps formed, and this helps provide a guide to future potential climate impacts.

Edited December 14, 2008 by scalbers

[SkepticLance]

Mokele

I do not suggest throwing out the baby with the bathwater. Models have their value, as I have said previously. However, it is scientifically correct to realise that they are works in progress, far from perfected, and it is healthy to maintain a level of scepticism about their accuracy.

 

A couple of other quotes from Dr. Lenny Smith.

" The climate community presents a united front......The downside is that if someone goes too far in interpreting model results, they don't always face proper scrutiny"

 

About the IPCC reports, he says :

"You have to read the qualifiers carefully, though. In the most recent report, for instance, there is an explicit acknowledgement that the range of simulations in today's models is too narrow. That is, future warming could be greater or less than what is suggested by the diversity between models in the report. It is good that the qualifier is there, but it is a hell of a qualifier to find on page 797"

[iNow]

About the IPCC reports, [Lenny Smith] says :

"You have to read the qualifiers carefully, though. In the most recent report, for instance, there is an explicit acknowledgement that the range of simulations in today's models is too narrow. That is, future warming could be greater or less than what is suggested by the diversity between models in the report. It is good that the qualifier is there, but it is a hell of a qualifier to find on page 797"

 

This is perfectly acceptable, and well within what we should expect if, say for instance, they don't start talking about models until page 798.

[swansont]

About the IPCC reports, he says :

"You have to read the qualifiers carefully, though. In the most recent report, for instance, there is an explicit acknowledgement that the range of simulations in today's models is too narrow. That is, future warming could be greater or less than what is suggested by the diversity between models in the report. It is good that the qualifier is there, but it is a hell of a qualifier to find on page 797"

 

Interesting that he only discusses a range of warming, and not the possibility of cooling. The comment also seemingly ignores that the IPCC did not predict a single value for the temperature increase, but a range of values.

[SkepticLance]

swansont

You should know by now that I am not a denier, or someone who predicts cooling. The most likely future, at least for the next 50 to 100 years, involves warming. It is the degree of warming that is moot.

 

Neither is Dr. Smith a denier. He is a good scientist involved in GCM's, who know their limitations and is not afraid to discuss those limitations. This is what makes him unusual. It appears, from his statements, that most modellers overhype their models and fail to admit to the limitations.

 

As far as the IPCC qualifier is concerned, my interpretation of Dr. Smith's comments is that the IPCC are aware of the fact that their range of models is inadequate, and the true result might be quite different to that which they are publishing. To cover their asses, they print a qualifier in a place where virtually no-one will read it. We could argue that this tactic is intellectually dishonest.

[swansont]

swansont

You should know by now that I am not a denier, or someone who predicts cooling. The most likely future, at least for the next 50 to 100 years, involves warming. It is the degree of warming that is moot.

 

I was quoting what Dr. Smith said, not you.

 

But why would you accept models that predict warming and not cooling, if they are so unreliable? Aren't models that predict cooling just as valid? Or is it that we know enough that we can exclude cooling as a scenario — doesn't that have some value?

 

Neither is Dr. Smith a denier. He is a good scientist involved in GCM's, who know their limitations and is not afraid to discuss those limitations. This is what makes him unusual. It appears, from his statements, that most modellers overhype their models and fail to admit to the limitations.

 

Again you have made a bald claim about a group of scientists without a whiff of supporting evidence.

 

As far as the IPCC qualifier is concerned, my interpretation of Dr. Smith's comments is that the IPCC are aware of the fact that their range of models is inadequate, and the true result might be quite different to that which they are publishing. To cover their asses, they print a qualifier in a place where virtually no-one will read it. We could argue that this tactic is intellectually dishonest.

 

But since that is pure conjecture, you can't really argue that, now can you?

 

On this topic, how do you feel about selective quoting? I mean, what was said in an article is buried there, and with no link, virtually no-one will read it. Someone then posts snippets that don't give the whole picture.

 

For example,

 

 

" The temptation to interpret model noise as forecast information invades our living rooms every night. ......."the details we see on TV weather forecasts are noise from the models. I think we are having exactly the same problem with climate projections."........"they cannot give us trustworthy forecasts of climate for regions as small as most countries are."

 

One might get the impression that Dr. Smith thinks GCMs are untrustworthy for predicting global effects.

 

But if we look at the article, one could have chosen to say

 

They are certainly right on the basic story of global warming. Man-made climate change is real. … The bottom line is that the models help us understand pieces of the climate system, but that does not mean we can predict the details.

 

Which paints a very different picture.

 

And you could have chosen to include this quote

 

Do you worry that the doubts you express about climate models could fuel the arguments of climate sceptics?

 

Yes I do. Effective application of climate science hinges on clear communication of which results we believe are robust and which are not. Any discussion of such limits can be abused by those seeking only to confuse. But failing to discuss these limits openly can hinder society's ability to respond, and also compromise the future credibility of science.

 

 

Which I think is spot-on.

 

The truth here is that Dr. Smith is not critiquing global models much at all. He's critiquing models being applied to local systems, which is pretty clear from his examples. And that does not contradict discussions that have taken place here. Local effects have more uncertainty associated with them, but this noise averages out when you look at the larger picture. Global averages have a much smaller uncertainty.

[SkepticLance]

swansont

It is all a matter of interpretation. You look at things one way, and I the other. However, I have not challenged the basic science, which is something my debate opponents seem to keep overlooking. I am simply saying that GCM's are not as accurate or reliable as some seem to think. Dr. Smith says the same thing.

 

 

Models predicting global cooling would be a surprise. They would have to have very good reason to do so, since the 30 year trend is warming. It would take a bit to convince me that such a model is valid, since it flies in the face of recent experience. Localised cooling may be a bit different.

 

You said

 

"But since that is pure conjecture, you can't really argue that, now can you?"

 

Of course it is conjecture. That is why I used the words 'my interpretation'. However, it makes sense. To call it "a hell of a qualifier to find on page 797" implies surprise. Dr. Smith expressed surprise that the qualifier was 'hidden' so far into the report, and there has to be a reason for this.

 

On selective quoting. I was not going to type out the entire interview - both because of copyright and because of the time required. Thus I had to be selective. I left out what was not relevent to the point. Since I was not arguing against the fact of warming, there was no need to include something affirming the fact of warming.

 

The message from Dr. Smith was not to overhype models. Treat them with healthy scepticism, which is something I have done consistently.

[Mokele]

The message from Dr. Smith was not to overhype models. Treat them with healthy scepticism, which is something I have done consistently.

 

What's the basis for your skepticism?

 

I'm not being flip - skepticism without basis is just being contrary for it's own sake.

 

For instance, I'm skeptical of many molecular phylogenies because I worry about long-branch attraction between long-separated modern taxa, taxon sampling effects, and molecular convergence. These are all legitimate, specific issues which particular, specific phylogenies may avoid, address, or account for.

 

So, what specific aspect and problems are the basis for your skepticism? How do you determine whether these problems are an issue in any particular given model?

 

Mokele

[SkepticLance]

Mokele

 

This has been a long, protracted issue. I have given many reasons for scepticism, including past errors such as Arctic ice predictions, current information lack, such as the detailed impact of cloud formation, unknowns such as oceanic currents and so on. I really do not want to repeat it all again.

[Chris C]

SkepticLance's stance that models (or anything for that matter) should be treated with a healthy skepticism is not a bizarre notion, and it's hard to believe that many people would disagree. There is a very detailed treatment of the strengths and limitations of GCM's here, and at least the summary should be read by those with a strong care of the issues

http://www.climatescience.gov/Library/sap/sap3-1/final-report/

 

They are not currently very good at the task of simulating sub-grid scale processes such as cloud microphysics, etc. Regional precipitation changes are not robust among ensemble members. Aerosol indirect effects and other things are still heavily paramaterized or not included at all (despite how realistic those paramaterizations may be) but since we're not up to the task yet of building a full-blown model with no empiricism whatsoever, care needs to be taken in long-term future projections. Care is usually taken in primary documents as to how uncertainty in models, assumptions, observations, etc are likely to effect the overall conclusion(s)--if at all.

 

We do not yet have adequate knowledge of ice sheet physics to make highly confident predictions concerning the magnitude and rate of ice loss (though they are certainly better than best guesses). OTOH, I have a lot of confidence in basic responses to changes in external forcings such as CO2, solar irradiance, etc...the "basic physical responses" to warming such as decreases in the pole-to-equator temperature gradient, landmasses heating up faster than oceans, etc are treated well in models. Responses which are robust among all models and different modelling groups (even with changes in initial conditions) such as "more CO2 gives you warming" are probably robust and it is unlikely that uncertainty in cloud physics or ocean dynamics are going to take away from that conclusion, especially ones with a solid foundation in theory and have reliable paleoclimatic constraints.

 

It is very difficult to explain on a blog/forum what kind of results are well known (and if the model result is likely good enough for policy-decisions) and what kind of stuff is still treated very much inadequately. You'll need to read authoritative documents such as the one above, IPCC, etc to see the recommendations of scientists and a more thorough treatment of individual sub-topics. Also, many things which are treated inadequately may still be constrained enough (by theory or observations) to not limit confident projections or hindcasts of other climatic variables. The notion in the swindle video or other venues for instance that "if one of the thousands of variables is incorrect, then the whole thing is worthless" is clearly not correct, and whether they are "useful" or not depends on what climatic variable you are talking about and the context around it.

 

C

 

http://www.chriscolose.wordpress.com

Edited December 16, 2008 by Chris C

[npts2020]

At any rate there are more reasons than any climate modeling (good or bad) to be able to discern that humans are having a major impact on the environment especially with regards to climate change. When someone can show me that human activity does anything besides add to any other cause of global warming, then I will agree it is not necessary to take action to severely limit those additions. Look at satellite photos of the poles for as long as they have been taking them. Visit a glacier and see how far it has receded in the past 40 years, there are several near Mt. Rogers in Canada that have been kept track of for at least that long. Look at migrating species, some have started going south two weeks or more later in the season or northward that much earlier. Even where I grew up in central Pennsylvania I can see the difference, in the 50's, 60's, and 70's it was normal to have snow on the ground all winter long once there was an initial heavy snow, in the past 20 years I would be surprised to learn that there had been snow all winter a single time. In the Poconos the season for our family maple syrup operation has definitely gotten earlier in the year by at least 2 weeks. In the 60's we never began setting up before mid-March, now you will miss much or all of the season if you wait til then, these days you want to be finished with setup before March 1. All of the syrup producers I have spoken with in the last ten years have told me similar stories about the season getting earlier as far away as Quebec and northern Maine. Look at temperature records for as many cities as you can as far back as you can get them, how many record or abnormally hot vs. cold days are there? None of this tells me that humans are the cause but then we come to ice cores. Ice cores are not a good year-to-year measure, however, they are very accurate for long term trends, which fortunately is what we are interested in for climate change discussions. Those long term trends tell us that the climate undergoes periodic changes of warm and cold, even fairly sudden ones on occasion. The part that should concern us is that those same ice cores tell us that the rate of warming is unprecedented for at least the past couple of hundred thousand years (as far back as they go). Once one accounts for all other possibilities, the elephant behind the curtain becomes human causes. Expecting a model to exactly predict what happens in the real climate, is similar to expecting one to model evolution and come up with a human after starting with a one-celled organism. Just because it can't be accurately modelled doesn't invalidate the theory which works in all other respects. If anyone wants links to support any of the above I will do my best to find them but it is basically a compilation of what I have experienced and read on the subject for the past 35 years or so.

[culvers3]

I realize that this is off topic, but I just got online. Just for the record, I do not deney that Global Warming is happening, I just disagree with the fact that most people think that we are the cause.

 

I mean people have been screaming Global Warming and Cooling since the late 1800's. And they keep switching it back and forth because in reality they have no clue what is happening they can just make assumptions, and those assumptions then get blown out of proportion.

 

So just let all of us make our own assumption because I bet that it will be a while before someone has any undisputable proof as to what is causing Global Warming, no matter what hypothesis that evidence may support.

[Mr Skeptic]

Um, there is indisputable proof that greenhouse gases and lower albedo cause global warming, and that particulates and higher albedo cause global cooling. No one who is sane disagrees with that.

[swansont]

I realize that this is off topic, but I just got online. Just for the record, I do not deney that Global Warming is happening, I just disagree with the fact that most people think that we are the cause.

 

I mean people have been screaming Global Warming and Cooling since the late 1800's. And they keep switching it back and forth because in reality they have no clue what is happening they can just make assumptions, and those assumptions then get blown out of proportion.

 

OK, now if you will be so kind as to provide evidence to back up the claim that the scientists have had no clue, and that all they do is make assumptions (which I am interpreting as "guess"). I don't care so much what "people" have been saying; if they have no claim to any expertise, it's just blather.

 

This is precisely the kind of thing to which I referred at the end of post #586

http://www.scienceforums.net/forum/showpost.php?p=451652&postcount=586

 

This demonstrates a profound lack of appreciation of what scientists are doing.

 

 

(holy crap, five-frikkin'-hundred eight-six)

 

So just let all of us make our own assumption because I bet that it will be a while before someone has any undisputable proof as to what is causing Global Warming, no matter what hypothesis that evidence may support.

 

Making your own assumption isn't how science works. If you want to start your own religion, it's fine, but be prepared to be ignored, since this is something that can be studied scientifically.

 

 

And in my experience in discussions about this and creationism, there is no such thing as indisputable proof™. There is no evidence that you can't find somebody who will dispute it. There are intellectually dishonest people, there are people who are ill-informed enough of the science that they end up arguing against a strawman, and there are people who are just plain contrary. Dispute it they will, so this is not the right metric to use.

[SkepticLance]

Like most of the others here, I disagree with Culvers. Warming over the past 30 years correlates very closely with CO2 rise, and there is no other possible factor that shows any similar correlation. While swansont is fond of saying that correlation does not equal causation, it is still a very strong hint that there is a causative factor involved, and if no other factor can be found, the correlating factor is probably the one. So the world is warming, and anthropogenic greenhouse gases are the cause.

 

I hope my stance on being sceptical of some of the details of warming can be treated with a bit more open mindedness, and less automatic opposition. We do need to be sceptical, until evidence is clear cut.

[iNow]

Like most of the others here, I disagree with Culvers. Warming over the past 30 years correlates very closely with CO2 rise, and there is no other possible factor that shows any similar correlation. While swansont is fond of saying that correlation does not equal causation, it is still a very strong hint that there is a causative factor involved, and if no other factor can be found, the correlating factor is probably the one.

Just to be clear, the evidence is much more than just "coorelation." There are empirical data which show without a doubt the effect CO2 has on blocking certain frequencies of IR, causing a blanketing effect and trapping heat, thus raising temps.

 

 

So the world is warming, and anthropogenic greenhouse gases are the cause.

Again, just to be clear, there are other causes, but anthropogenic contributions are by far the greatest single contributor to the change.

 

 

I hope my stance on being sceptical of some of the details of warming can be treated with a bit more open mindedness, and less automatic opposition. We do need to be sceptical, until evidence is clear cut.

 

While I agreed with you above, and was simply supplementing what you said, I must disagree with your closing. Being open minded does not mean you accept anything. It's not "open minded" to say, "The last million times we injected mice with this chemical it killed them, but hey, I'm open minded, I may as well try again. They will probably survive this time." Stuff like that is ignorant, not open minded.

 

Also, since skepticism is implicit in the scientific method, I see no reason to wait until things are "clear cut" to stop. It's always present. We are perpetually skeptical. However, when the data is in, we need to move past the skepticism, as it soon bleeds into unfounded denial, obfuscation, and a waste of everyones time.

 

Again, Lance, I know you're not a denier, but you do sometimes repeat their fallacies. Focus more on real numbers and data and all will be well. That's a good dogma to hold.

[The Bear's Key]

Mokele

 

This has been a long, protracted issue. I have given many reasons for scepticism, including past errors such as Arctic ice predictions, current information lack, such as the detailed impact of cloud formation, unknowns such as oceanic currents and so on. I really do not want to repeat it all again.

"They've been wrong before" is not a reason for skepticism. A much better reason is not having looked at the evidence yourself. In between replicating the experiments and combing the data, skepticism is healthy. Wise, in fact. Yet just being a skeptic for the label's prestige, tends to be stupid.

 

Few will be able to replicate experiment or review the data, so it's a perfect opportunity for politicians and/or the affected industries to confuse the issues. Be skeptical of them as well. However, unlike science, they have no formal manner of recording their views for experimental analysis. In other words, their conclusions are merely opinions that can't be dissected in a lab, and they don't have a larger peer-review body that automatically double-checks their results with the understanding their peers will make every attempt to poke holes through it.

 

Science welcomes the fine scrutinizing of every bitty detail by complete strangers in the field, because that's what real scientists do. The opposition has no such intellectual architecture. They have no rigid, self-imposed, and neutrally "open to all" type of checks and balances.

 

And due to all that, it's easy for them to confuse the issues. It's fine scrutiny vs. closed door meetings and strategizing. The opposition, industries, politicians can afford the money to do astroturf. In fact, we may have some of those occasionally dropping by here for all we know.

[Mokele]

Science welcomes the fine scrutinizing of every bitty detail by complete strangers in the field, because that's what real scientists do.

 

I should note that in my field, I can immediately call to mind two papers written by statisticians who basically said "You're doing your math wrong", and far from being repressed or rjected, these papers were published in top-tier journals, given space beyond the usual for those journals, and are required reading in every biology graduate program (and many of the better undergrad programs).

 

Mokele

[Reaper]

Good grief! You mean to tell me that this stupidity is still going on? After 621 posts and 7 months?.

[Sayonara]

Yup.

 

When scientists decide to make a monster they usually get it spot on.

[JohnB]

Science welcomes the fine scrutinizing of every bitty detail by complete strangers in the field, because that's what real scientists do.

Really? Then how would you classify someone who says "Why should I make the data available to you, when your aim is to try and find something wrong with it."

[iNow]

Really? Then how would you classify someone who says "Why should I make the data available to you, when your aim is to try and find something wrong with it."

 

Where was this said, and by whom? Context would help in addressing your inquiry.