Climate Change Skepticism

[Riverwind]

Yes there is a large amount of uncertainty with clouds but models are currently ttempting to reduce that uncertainty by using different sets of cloud modeling parameters – one for instance has been running over 60,000 different simulations, so that is definitely not ignoring clouds.

Specific criticisms about modelling clouds are symptoms of a much larger problem with scientific computer models (a topic which I do have personal experience with). All computer models use the laws of physics/chemistry as a starting point, however, these laws depend on physical parameters that must be measured and/or estimated. The usefulness of the model output depends entirely on the quality of data used to estimate the various fudge factors. In complex systems the number of fudge factors is huge and it is not possible to measure or estimate most of them accurately. For that reason modellers must calibrate their models by comparing the output to the real world and adjusting the fudge factors until the actual output matches reality.

What this means is computer models are very sensitive to the assumptions built into them. For example, if you build a computer model based on the assumption that CO2 is the primary driving factor then you will end up with a computer model that confirms your assumption - even if that assumption is completely wrong! Scientists deal with this problem by conducting real experiments and verify that their models predict the outcome. Models that are built on incorrect assumptions do not predict outcomes well and the scientists discover this very quickly. Unfortunately, we don't have a climate lab that allows the modellers to validate their models against reality. This means we have no way to know if the assumptions built into the models are correct.

Many AGW advocates don't seem to understand the limitations of the models they use. For example, The IPCC report itself makes the assertion that we should have 'confidence' in models because they predict the past - a claim that is completely absurd because the data about the past was used to create the models in the first place.

In other words, the computer models do not provide proof of anything and we should not be making fundemental economic and social decisions based on the output of these computer models.

Furthermore several skeptics do accept the computer models, the most well known would probably be Lomborg, who in his recently released “Cool It” endorses accepting the IPCC middle of the road climate predictions.

I suspect that Lomborg is being pragmatic and plays lip service to the models because he wants people to listen to his arguments about economic decision making. All of the skeptics that look at this problem from a scientific perspective reject the models as definitive proof of the effects of CO2 induced warming.

I will have to check to see if Christy and Spencer ever released their data and computer source code. Last I checked they hadn't.

Christy has (according to climate audit) and he got beat up because of it. McIntyre points out that scientific journals and funding agencies generally require authors of peer-reviewed research to archive all of the data necessary to reproduce their research. In other words, McIntyre is only asking the journals and funding bodies to enforce long standing policies.

Studies I have seen have shown that UHI has only minimal effect on the records - both present day and historical. Skeptics have a tendency to have an issue with those studies, but I have yet to see them do their own study.

That is not true. McKitrick released a recent statistical analysis that demonstrates a co-orrelation between higher temperatures and urban areas. Their analysis suggests that up to half of the recent warming could be due to the UHI effect.

If his results are different from theirs than other groups can attempt to reproduce the results and if there appears to be fraud then that can be investigated. My problem with the releasing of source code is that it allows others who are attempting to reproduce the results to do so by copying instead of doing original work.

Your position makes sense if this was a purely academic discussion. However, this research is being used to justify some pretty major economic decisions which means a different set of rules is required. For example, would you invest money in a company based on the financial data released by the company or would you insist that independent auditors review the financial data?

But, anyways that doesn’t mean that I don’t like McIntyre, I actually think that the field of climatology is better off with him around then without. But I certainly wouldn’t use him as a primary source of information about climate change. However, I really don’t like Milloy.

McIntyre is an analyst that provides a useful sanity check on claims made by others. However, he does not do his own research into hows and whys of climate change. Milloy is a website author who simply repeats what others have told him.

As for tree rings, you have issues with the IPCC on that issue, I have issues with Lohle (sp?), but overall I don't really think it matters much. Whether or not the MWP was as warm or even warmer than today means little. The cause of the MWP was different than the cause of current warming.

We don't really know what is causing the current warming so comparisons to the past are quite relevant. The CO2 as the primary driver hypothesis is much less plausible if it can be shown that similar temperature rises have occurred in the past without any connection to CO2.

I am not an expert on ice ages. My understanding is that the causes have to be the same as the traditional causes of warming: Milankovitch cycles, atmospheric gas concentrations, solar energy levels and volcano emissions.

The argument advanced today is that CO2 is a major driver of climate change. The lag between CO2 levels and the temperature rises in the ice core records are explained by suggesting the temperature rose slightly due to the sun and was later amplified by CO2 released from the oceans. However, if this was the case then we should have seen runaway global warming due to CO2 induced positive feedbacks. Even if we accept that the CO2 induced rise halted due to unknown negative feedbacks that does not explain how come temperatures later fell while the CO2 levels remained high. If CO2 is a powerful driver of climate then it would have taken a powerful cooling effect to over come this driver. If the Milankovitch induced cooling was strong enough to overcome the CO2 effect then why would Milankovitch induced warming be insignicant without CO2? A more plausible hypothesis is the influence of the sun on climate is much larger that what one would expect given simple measurements of TSI levels.

Our current level of CO2 is already much higher than that and we have the ability to increase the CO2 levels by 80 ppm in a period of a decades.

Yet we have seen only a modest warming that is no worse than warming trends in the recent past. That suggests that the influence of CO2 on the climate is much less than what AGW advocates suggest.

Why should any scientist who says such baloney be given the time of day by real scientists who are busy?

I realize that there is a lot of rubbish produced on this topic and that it is not pratical to refute everything. However, the AGW advocates like those on realclimate seem to be quick to reject all counter evidence no matter what the source. The quick dismissal of recent works by McKitrick, Spencer and Christy are good examples. Sometimes saying "you have some good points that need to be investigated further" is the most appropriate response. I get the impression that the AGW camp is scared to admit any weakness because it would give ammunition to the 'do nothing' camp. Unfortunately, this attitude means that I cannot take anything they say at face value.

I disagree with that statement. There is a wide range of computer model predictions and the IPCC has been honest about the uncertainties.

The "wide range" is a big part of the problem. The IPCC has so many models with so many predictions that pure chance dictates that some of them will be right some of the time. What the IPCC should be doing is comparing the models to reality and discarding those that are clearly wrong. Unfortunately, the IPCC seems to use any partial success with some of the models to claim that the entire suite of models are legimate reflections of reality.

I also disagree with your assessment that those models have done a poor job predicting trends. Hansen's computer model predicted the changes from the effects of Pinatubo extremely accurately.

Hansen's model predicted changes up until 1998. After that it has failed miserably. climateaudit compares Hansen's model to the most recent HadCRUT3 dataset. As you can see the actual climate is warming much more slowly than predicted. I realize this is an older model but I have noticed a trend where all models consistently overestimate the effect of CO2 induced warming. In my view, this is a sign of a systematic error and that we should be re-evaluating the assumptions built into the models. Edited January 3, 2008 by Riverwind

[Wild Bill]

What this means is computer models are very sensitive to the assumptions built into them. For example, if you build a computer model based on the assumption that CO2 is the primary driving factor then you will end up with a computer model that confirms your assumption - even if that assumption is completely wrong! Scientists deal with this problem by conducting real experiments and verify that their models predict the outcome. Models that are built on incorrect assumptions do not predict outcomes well and the scientists discover this very quickly. Unfortunately, we don't have a climate lab that allows the modellers to validate their models against reality. This means we have no way to know if the assumptions built into the models are correct.

Unfortunately, many AGW advocates don't seem to understand the limitations of the models they use. For example, The IPCC report itself makes the assertion that we should have 'confidence' in models because they predict the past - a claim that is completely absurd because the data about the past was used to create the models in the first place. This demonstrates that this lack of understanding is not limited to non-scientists.

In other words, the computer models do not provide proof of anything and we should not be making fundemental economic and social decisions based on the output of these computer models.

Gee, it sounds like the "Club of Rome" all over again. They based political and social decisions on expensive changes to entire countries on one of the earliest computer models that was to prove totally bogus!

[jbg]

Gee, it sounds like the "Club of Rome" all over again. They based political and social decisions on expensive changes to entire countries on one of the earliest computer models that was to prove totally bogus!

More like Club of Rome than you realize; it's a self-fulfilling approach to limits of growth.