Entropic Man, and you have a motive to keep denying science which is rewarding I am sure.

This thread was about the pointlessness of climate models, as Schrodingers Cat has just pointed out.

EM, the strawmen have been of your manufacture, assisted by Raff. It is all over this thread.

Nice Tag Team work, but not exactly science.

Down among the molecules the energy flows and the particles interact in accordance with the laws of physics. That is what I mean by deterministic.

Got it..

EM, I asked you a straight question. As pointed out much earlier, the validation of models depends on their ability to correctly simulate the system they claim to emulate. Climate models fail by any standard.

Do you agree or not? A non answer will be taken as your reluctant agreement.

If you disagree, please explain in what way the models predict reality sufficiently to overturn our definition which is the definition adopted universally in science and briefly repeated in my second sentence above.

Raff tries to divert attention......

"Nial, "optimising the models against past forcing values"? What makes you think this is what they do?"

...from the point.....

The rest of us realise that they are intimately linked, there is no worth in optimising the models against past forcing values if you can't predict what future forcings are going to be.

Schrödinger's cat

The 295 runs in the CMIP5 ensemble modelled a range of possible forcing intensities.

Those wit higher modelled forcings than actually observed. gave temperatures for 2015 higher than observed, as one would expect.

Those wit lower modelled forcings than actually observed gave temperatures for 2015 lower than observed, as one would expect.

Those whose modelled forcings matched observed forcings gave temperatures for 2015 which matched observation, as one would expect..

The CMIP5 models work just fine. How you turn this into "All the models are wrong" is beyond my comprehension.

Simon Hopkinson, Martin A

I used to fall into that old trap. All any deterministic system has to do is operate by its own internal rules. Its operation does not have to be transparant.

There is no requirement for a deterministic system to produce outcomes which are predetermined, inevitable or exactly predictable by human beings.

Nial, again, what makes you think scientists are "optimising the models against past forcing values"? What does that mean to you?

Martin, come on, is calibration of the sort described in your link the same as validation? It is a simple question. You imply that it is, but you wont say so directly. If it is, then why use a different word. If it isn't then why does anyone take UAH and RSS so seriously when they are using non-validated models? You all claim that GCMs are rubbish because they are not validated. Maybe you are like Simon who can somehow detect a pause while thinking that none of the temperature series (in which he might detect a pause) is valid. Maybe BH has two clairvoyants.

Nial
I checked the gold standards for Climate Science, and it seems you are right in what you say about forcings being added and adjusted in models.

So all models are first tested in a process called Hindcasting. The models used to predict future global warming can accurately map past climate changes. If they get the past right, there is no reason to think their predictions would be wrong. Testing models against the existing instrumental record suggested CO2 must cause global warming, because the models could not simulate what had already happened unless the extra CO2 was added to the model. All other known forcings are adequate in explaining temperature variations prior to the rise in temperature over the last thirty years, while none of them are capable of explaining the rise in the past thirty years. CO2 does explain that rise, and explains it completely without any need for additional, as yet unknown forcings.

Where models have been running for sufficient time, they have also been proved to make accurate predictions. For example, the eruption of Mt. Pinatubo allowed modellers to test the accuracy of models by feeding in the data about the eruption. The models successfully predicted the climatic response after the eruption. Models also correctly predicted other effects subsequently confirmed by observation, including greater warming in the Arctic and over land, greater warming at night, and stratospheric cooling.

https://www.skepticalscience.com/print.php?r=21

AOGCMs internalise as many processes as are sufficiently understood. However, they are still under development and significant uncertainties remain. They may be coupled to models of other processes, such as the carbon cycle, so as to better model feedbacks. Most recent simulations show "plausible" agreement with the measured temperature anomalies over the past 150 years, when driven by observed changes in greenhouse gases and aerosols. Agreement improves by including both natural and anthropogenic forcings.

https://en.wikipedia.org/wiki/General_Circulation_Model

GCMs perform calculations with timesteps of about 20 to 30 minutes so that they can capture the daily cycle and the progression of weather systems. As with weather forecasting models, the weather in a climate model is chaotic. Starting from a very similar (but not identical) state, a different simulation will ensue – with different weather, different storms, different wind patterns – i.e different wiggles. In control simulations, there are wiggles at almost all timescales – daily, monthly, yearly, decadally and longer – and modellers need to test very carefully how much of any change that happens because of a change in forcing is really associated with that forcing and how much might simply be due to the internal wiggles.

http://www.realclimate.org/index.php/archives/2008/11/faq-on-climate-models/

Supported by others, for example

It seems unlikely that the anti-correlation between forcing and sensitivity simply happened by chance. Rational explanations are that 1) either modelers somehow changed their climate sensitivities, 2) deliberately chose suitable forcings, or 3) that there exists an intrinsic compensation such that models with strong aerosol forcing also have a high climate sensitivity. Support for the latter is found in studies showing that parametric model tuning can influence the aerosol forcing . Understanding this complex is well beyond our scope, but it seems appropriate to linger for a moment at the question of whether we deliberately changed our model to better agree with the 20th century temperature record.

http://judithcurry.com/2013/07/09/climate-model-tuning/

I used to fall into that old trap. All any deterministic system has to do is operate by its own internal rules. Its operation does not have to be transparant.

Apart possibly from Attp, are there others that share this conviction?

Yes,yes, EM, I get the picture. So the class of deterministic systems includes:

- Emission of gamma ray photons from a sample of cobalt-60
- A human being
- Brownian motion
- The noise voltage appearing across a hot resistor

etc etc

Are there many who share this belief? ATTP it seems.

As I have said before EM, you have a tendency to imagine something and that then promptly becomes, for you, reality.

There is no requirement for a deterministic system to produce outcomes which are predetermined, inevitable or exactly predictable by human beings.
Jan 20, 2016 at 12:27 AM | Unregistered CommenterEntropic man

For a completely deterministic process predictability is 100%. You can project past and future values exactly.(...)
Jan 15, 2016 at 6:56 PM | Unregistered CommenterEntropic man

Raff tries the same distraction, SandyS kills this distraction branch nicely, thanks.

The point again......

The rest of us realise that they (models and forcings) are intimately linked, there is no worth in optimising the models against past forcing values if you can't predict what future forcings are going to be.

Sorry, but this is just utter nonsense.

The rest of us realise that they (models and forcings) are intimately linked, there is no worth in optimising the models against past forcing values if you can't predict what future forcings are going to be.

There is essentially a direct relationship between forcings and concentrations. The reason we can't predict what furture forcings will be is because we don't know what we will do as far as emissions are concerned. However, we can consider various possible future pathways. Hence we can use models to estimate what will happen if we follow a high emission pathway, a medium emission pathway, or a low emission pathway. Not being able to predict what future forcings will be does not mean that we cannot try make predictions that are conditional on the pathway that we actually follow.

By your logic, we can never say "if we do X, Y will probably happen". According to you, unless we know precisely what we will do in future, we can never try to understand what might happen. Might as well go back to the Dark Ages.

What WE will do as far as emissions is concerned is one of the LEAST uncertain of all climatic considerations.

Well, then we can predict the future forcings.

Simon Hodgkinson

I am sure that your 12.04 statement was intended to be facetious, but it is probably true..Under 19th/20th century conditions all the natural forcings have been neutral or slightly negative. Without human input the 20th century would have stayed at the same temperature as the latter 19th century, around 13.8C.

Nial, Sandy thanks for the links. From what I read, aerosol forcing does seem to be adjusted to tune (at least some, maybe all) models, so I conceded the point. But I don't understand why "there is no worth in optimising the models against past forcing values if you can't predict what future forcings are going to be". That seems strange.

Martin,

Apart possibly from Attp, are there others that share this conviction?

Don't look at me, I'm out of my depth... But I can still try to understand whether calibration of the sort described in your link the same as validation. Is it?

The problem is one of mindset. Warmists convinced themselves that CO2 is the dominant forcing during the warming of the second half of last century. Hindsight and common sense now suggests that a high proportion of that warming was due to natural changes which may now be going into reverse. There is a reluctance to contemplate the failure of fifty years of modelling.

The “science is settled” obsession with radiative forcing now leaves the science wrong footed since little is known about other possibilities. I refer to solar modulated cloud formation, UV variability in solar output and other factors that may affect albedo.

Hindsight and common sense now suggests that a high proportion of that warming was due to natural changes which may now be going into reverse.

Where does that conclusion come from?

Another problem concerns assumptions about feedbacks. Positive water vapour feedback was a useful amplifier at the time when the rate of warming was very high. The stability of our climate and, indeed, our continued existence, suggests that our climate is dominated by negative feedbacks.

The IR blocking in the atmosphere by CO2 does not lead to the theoretical level of surface warming or a troposphere hotspot for the simple reason that water vapour radiates the excess heat to space.

For too long, the models have assumed radiative warming and aerosol cooling but in order to try to achieve realistic temperatures the values of these parameters themselves need to be unrealistic.

These are the sorts of issues that need to be addressed but to do so risks the collapse of the “settled science”. This is why the issues raised in this post are never properly admitted or debated.