A Climategate thought

[JohnB]

One of the emails contains a bit that demonstrates part of my concern regarding attribution of climate forcings.

Kevin Trenberth said;

The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't.

email here.

 

I see this as a problem in logic. One of the main attribution arguments is that we understand the natural forcings and systems and can account for them, therefore we know that CO2 is a major driver.

 

However, if that were in fact the case, then wouldn't we therefore also know which forcing or part of the system has "reversed" itself and be able to account for the "lack of warming"?

 

It seems to me that the two go hand in hand. If you know one, then you must know the other. Opposite sides of the coin, so to speak.

 

Conversely, if we don't know what negative forcings are causing the current lack of warming, how could we say with certainty that we know all the factors that contributed to the warming in the first place?

 

Thoughts?

[swansont]

The context of his arguments, and that statement, is not about forcings. It is about the various places the energy goes, and our inability to track those paths.

 

It would be as if a physicist, discussing an inelastic collision, said "The fact is that we can't account for the reduction of kinetic energy at the moment and it is a travesty that we can't." We know energy is conserved, but don't know where it all went. We don't have the diagnostic instruments in place to track it.

 

 

BTW, the paper linked in the email in the paragraph preceding the quote is outdated. The updated version is

http://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/EnergyDiagnostics09final2.pdf

[JohnB]

Hmmmm. Fair enough, thanks. There are still some questions, but I'll post them when I can (hopefully) put them in a clear fashion.

[bascule]

The context of his arguments...

 

Always helps.

[toastywombel]

Also the lack of warming seems to be attributed to the solar cycle. However, the study they were referring to in that conversation predicted that the climate would continue to warm regardless of the solar cycle. Kevin even cited the concerns he had in his paper which was published.

[bascule]

Also the lack of warming seems to be attributed to the solar cycle.

 

That's certainly a component of it. Solar output is unexpectedly low.

[toastywombel]

Bascule could you give me some links to solar output information? I am curious about it.

[iNow]

Bascule could you give me some links to solar output information? I am curious about it.

 

Here's one in context:

http://scienceblogs.com/startswithabang/2009/04/the_solar_cycle_and_global_war.php

[bascule]

Bascule could you give me some links to solar output information? I am curious about it.

 

http://science.nasa.gov/headlines/y2009/01apr_deepsolarminimum.htm

[toastywombel]

Thanks for the links iNow and bascule.

[JohnB]

I've read the revised paper and I must admit I'm not so sure that the situation is any better.

 

Figure 2 of the UCAR paper shows the energy budget, something I think we've all seen before in one form or another.

 

Put bluntly, isn't he arguing that due to a lack of data we can't actually confirm the transfers within the system?

 

More to the point, we can't measure the transfers in the budget at all. If we could, we would be able to see which one(s) had changed and therefore know where the energy had gone?

 

So we have 341W/m-2 coming in and 341 W/m-2 going out (in a balanced system) but no way measuring what is actually happening inside the system. We can't measure or prove a single value in the internal workings of the budget.

 

If this is the case then he's right, it is a travesty. While it doesn't impact the GW debate that much, it does show where some money should be spent.

 

I also note that he mentions Dr. Spencers idea that a 1% change in cloud cover can roughly account for recent warming.

[bascule]

Put bluntly, isn't he arguing that due to a lack of data we can't actually confirm the transfers within the system?

 

More to the point, we can't measure the transfers in the budget at all. If we could, we would be able to see which one(s) had changed and therefore know where the energy had gone?

 

Yes, this is the case. Instead climate scientists create a hypothesis about the various radiative forcings based on their best understanding of the climate system to date, and use these as inputs to climate models. The experiment takes the form of whether or not the provided radiative forcings, as inputs to the climate model, result in an accurate reconstruction of the instrumental record.

 

So we have 341W/m-2 coming in and 341 W/m-2 going out (in a balanced system) but no way measuring what is actually happening inside the system. We can't measure or prove a single value in the internal workings of the budget.

 

Yes, that's right, it's hard to obtain accurate measurements as to the thermal fluxes of the climate system, because it's the largest complex dynamical system on earth that humans have attempted to study and skillfully predict.

 

If this is the case then he's right, it is a travesty. While it doesn't impact the GW debate that much, it does show where some money should be spent.

 

Because we have models of how the climate system operates, and can use hypotheses about the radiative forcing effects as climate model inputs. If these inputs do not accurately reconstruct the historical temperature record, then either they're wrong, or the models are wrong. It's a Herculean effort to accurately reconstruct the historical record within a climate model, but when we do, it tells us we're on to something.

 

Climate scientists are doing their best given the difficulty of studying a complex dynamical system full of nonlinearities and feedback loops. I think it requires a relatively nuanced understanding of the problem to even come to the realization that the climate system can, in fact, be modeled. If you have an axe to grind, you should be arguing that multi-decadal GCM reconstructions are not yet skillful enough to produce realistic outputs.

 

But please, don't trivialize decades upon decades of atmospheric science research. These are not satellite photos, they are a GCM in action:

 

tbXwRP0CQNA

[JohnB]

So, um, where has the energy gone?

 

This is the point. The GCMs don't show it.

 

For example (and just as a suggestion). The recent hiatus could be due to increased temps and WV forming more clouds and reflecting more incoming radiation.

 

I think that this is what Trenberth was saying. If such a negative feedback existed and was messing up the budget, we have no way of detecting it.

 

AFAIK such a negative feedback is not included in the workings of models (from my readings, there seem to be very few negative feedbacks considered at all) so better detection would be of great value in improving those models. (If such a feedback existed of course, but better detection would be a plus in it's own right.)

 

If you have an axe to grind, you should be arguing that multi-decadal GCM reconstructions are not yet skillful enough to produce realistic outputs.

A bit hard to do when we get averaged output from ensemble runs, wouldn't you say? That's what Douglass tried (although it was a poor paper) and was roundly castigated for looking at the "mean" rather than the "spread".

[iNow]

Model accuracy is pretty solid, and has already been addressed:

 

http://www.scienceforums.net/forum/showpost.php?p=441763&postcount=7

[bascule]

So, um, where has the energy gone?

 

This is the point. The GCMs don't show it.

 

*shrug* I certainly can't answer that question. As far as I can tell it remains an open problem.

 

This is why Kevin Trenberth is pointing it out as such. Then Fox News got ahold of it and made him look like he was suppressing some sort of that evidence global warming is a big lie.

[JohnB]

Model accuracy is pretty solid, and has already been addressed:

So where has the energy gone? The models certainly don't answer that question.

 

You would also have to agree that if there is no way to measure the internal changes in the energy budget then there is also no way to check whether the models accurately reflect those changes?

 

A model might get the right answer, but is it for the right reasons? It would seem that at least internally, there is no way to check.

 

bascule. If it seemed like I was having a go at Trenberth, I didn't mean to give that notion. My reading of the email is that a researcher was complaining of a lack of measurment data, without which his science was put in a bad position for checking assumptions. A very valid complaint.

 

A question for you both. Since most current models do not show where the energy has gone, if there was one that did, would it not be worth careful consideration?

Edited December 21, 2009 by JohnB

[D H]

So where has the energy gone? The models certainly don't answer that question.

The models most certainly do answer that question. It has gone into raising the temperature of the Earth. Temperature is a measure of energy. (That is what kinetic theory is all about.)

[swansont]

The models most certainly do answer that question. It has gone into raising the temperature of the Earth. Temperature is a measure of energy. (That is what kinetic theory is all about.)

 

Which part of the earth is the question.

[bascule]

Since most current models do not show where the energy has gone, if there was one that did, would it not be worth careful consideration?

 

Of course

[JohnB]

Cool. I've been following DR. Spencer work on cloud variability forcing/feedback and find it interesting. The pdf of his presentation to the fall AGU meeting is here.

 

The work is interesting and his simple model does explain satellite data, something which the more complex models don't seem to do.

 

I don't know if his comments that all IPCC models use clouds as a positive feedback is correct. Do you have any idea on this claim?

 

Didn't you say that you had done some work in this area? I'd like your opinion.

[bascule]

Didn't you say that you had done some work in this area? I'd like your opinion.

 

My work involved helping integrate Fortran code between our existing model and a cloud model. I'm a computer scientist, not a climate scientist.

 

Regarding clouds and whether they represent a positive or negative feedback, I believe that's also an open question.

[JohnB]

Sorry, my mistake.