Thursday, January 17, 2008

1988 and all that

As soon as the nonsense about global temperature not changing in a decade started, the lab bunnies knew what was coming, so they took out their crayons (very traditional they are, no magic markers allowed in the burrow) and started adding points to Hansen's 1988 graph

Of course, being ethical Rabetts, we used the GISS surface stations record which includes the polar regions. As we all know the models, including Grandpa Hansen, predict that the greatest warming will be in the Arctic, so if you use a surface temperature method or one of the MSU records that do not include the Arctic, it will appear that the models under overpredict (the logic was fine, the execution sucked. Thanks to Mike for pointing this obvious nuttiness out, anyhow youse knew what Eli meant).

The 1988 model appears to be a bit low even compared to scenarios B and C. Only Pat Michaels thinks that scenario A was the most likely, but still. Climate model forecasts depends on the scenario that predicts greenhouse gas concentrations. (OK, if your name is Piers Corbyn maybe not). We OTOH need to look at the predicted forcings which we can get from the NOAA annual greenhouse gas index (btw, the latter has a neat little toy under data visualization that let the little guys look at station data. Auditor's delight)
The total forcing is well fit by a hinged line with a break at 1990. What happened was the Montreal Protocols which flattened the concentration of the CFCs and better recovery of methane from oil wells, so it could be sold. Let's take a look at the forcings that were predicted in the 1988 paper and compare with what actually happened. So let's start from the forcings shown in Hansen, et al (1998) and put the NOAA forcings on top of them and extrapolating Hansen, et Als. (apologies to the Als, the anonymice of scientific papers) forcings to the future we get

where we have set the zero of the NOAA forcings to 1960 to better match that of Hansen, et Als. Since Hansen, et Als. forcings are noiseless, and the NOAA ones are compared to some average value around 1750, this is not a full Eschenbach not even a half one because as anyone can see from the figures, there is a lot less noise in the forcings than in the global surface temperatures.

The sharp eyed Auditoriums have seen that the NOAA forcings are higher than the GISS ones. These are all calculated from concentrations, but using slightly different formulas. So, what does this say about the model. In Hansen's 1988 words

The climate model we employ has a global mean surface air equilibrium sensitivity of 4.2 C for doubled CO2. Other recent GCMs yield equilibrium sensitivities of 2.5-5.5 C.....

Forecast temperature trends for time scales of a few decades or less are not very sensitive to the model's equilibrium climate sensitivity (reference provided). Therefore climate sensitivity would have to be much smaller than 4.2 C, say 1.5 to 2 C, in order for us to modify our conclusions significantly.
We are getting to the point, twenty years on, where the high estimate of climate sensitivity is making itself felt. OTOH, the 1988 paper estimated the forcings slightly on the low side. The result was a pretty good prediction. Definitely in the class of useful models.

22 comments:

David B. Benson said...

When was the 'altithermal'? I know about the Eem (termination 2).

Anonymous said...

That McIntyre, Pielke and others have to use Hansen's 20 year old model to show that models are inaccurate is a pretty good indication of where they are coming from.

When Hansen testified before Congress, global warming was as yet an unproven phenomenon..

Hansen did very well indeed with his projection given the uncertainties that existed at the time.

It's pretty pathetic that people like McIntyre need to use Hansen as a punching bag to make themselves feel useful and smart.

Steve Bloom said...

Very thorough, Eli. Thanks. Are we detecting the signs of increasing embitterment on the part of ole' Stevie Mac?

David, "altithermal" is another name for the Holocene Thermal Maximum (although sometimes "Optimum" is used rather than "Maximum"), which was a Milankovitch cycle-driven longish (@3,000 years IIRC) warm period in the mid-Holocene.

David B. Benson said...

Steve Bloom --- Termination 1, thanks.

Deech56 said...

Going to the CA thread, I pondered the sound of one shark jumping. I learned that Gavin is a NASA employee and that our esteemed lagomorph is a NASA apologist. From the comments I also learned that Hank Roberts and Ray Ladbury were RC gatekeepers. From now on the phrase "NASA employee Gavin" will be as familiar as "circumspect Penelope".

EliRabett said...

Given what they paid me NASA should apologize.

Mike said...

"As we all know the models, including Grandpa Hansen, predict that the greatest warming will be in the Arctic, so if you use a surface temperature method or one of the MSU records that do not include the Arctic, it will appear that the models underpredict."

Don't you mean "overpredict"?

Doesn't the GISS temperature record estimate temperatures over polar regions? What if that is correct, could you point me to an explanation of the technique.

EliRabett said...

Hi Mike, yep on the predict

For an explanation of GISSTEMP go to
http://data.giss.nasa.gov/gistemp/references.html

You basically want the Hansen, Ruedy and Sato papers from 1996 and 1999. The drummer changed somewhere in between.

stevesadlov said...
This comment has been removed by a blog administrator.
Anonymous said...

"Are we detecting the signs of increasing embitterment on the part of ole' Stevie Mac?"

Either that or the signs of increasing derangement -- or perhaps both (would that be "embittered derangement"? or "deranged embitterment"?


"Given what they paid me NASA should apologize."

Well, that depends what you gave them in return, doesn't it Eli?

So, did you give them a small hop for a rabbet? (worth $5)

Or a giant leap for rabettkind? (worth $15)

Anonymous said...

You guys demonize Steve M quite wrongly. He is a fellow with a very restless intelligence, the kind of person who would do crossword puzzles or write programs. As it happens, he's turned his attention to tracking down the detail of climate science papers.

It is a very narrow focus. It is not about refuting AGW, though many of you seem to think any such enterprise must be that. It is just about going through the papers and arguments and fleshing them out and seeing whether they are valid.

Its not embitterment or anything of the sort. Its good clean fun and exactly what climate science needs but will not do for itself for some reason.

I would add one very serious point in defence of CA. CA is the only climate blog where you will find chunks of R code posted for readers to verify procedures and results. You're not going to find this here. The level of detail that stuff gets examined on in CA is at least as thorough, probably more so, than RC. And unlike RC, CA is not politically funded by a large organization. Given this, CA is rather an amazing achievement.

People sometimes say that Steve M has not found much. You can argue, but whether he does is not his value. There is a value to careful detailed examination of the papers, regardless of what you find.

In the end, if you object to CA, your real objection is to free discussion and verification of results. That's all it is. You need to stop sniping and start reading, and not get all het up if you don't agree with everything Steve writes. I don't either, but he is the most informative and specific blogger on any of these issues. Tamino is quite good too, but nothing like as detailed and specific. RC suffers from continual lapses into rants.

Also, don't confuse Steve M with the contributors. Any more than you should confuse the anonymice with Eli. They are different, and Steve M is not responsible for views and analyses other than his own. Any more than Eli is.

Anonymous said...

Anon 1:27 says "As it happens, he's turned his attention to tracking down the detail of climate science papers."


Ah, yes, McIntyre is interested in the fine "details"... which is why he does not carefully read the papers he criticizes, right?

Had he done so in the case of the Hansen '88 paper, he would certainly have known that Hansen said in the paper that

"Scenario B is perhaps the most plausible of the three cases"

and McIntyre would not have claimed as he did that
"Hansen has subsequently said that Scenario B was said by him at the time (in his testimony) to have been the "most plausible", although the article itself contained no such statement."


McIntyre calls that "auditing"?

What a joke.

And the complaints about not having his comments posted on RC on Christmas Eve and the like are just nutty.

Anonymous said...

Steve M can make mistakes. He is human. I do not think the record on the Hansen material is as you represent it. But that is hardly the point. Steve M is doing a job no-one else can do, and in the main doing it carefully, accurately and very openly.

You can see this if you would like to verify Hansen's models. Where is the code? Where is Thompson's archived ice core data? Why did it take an FOI request to get the names of Jones' Chinese stations? Why did it take a Congressional Committee to get some of Mann's materials?

We need Steve M, with all his imperfections. His recent notes on Hansen were work in progress like much of his stuff. His material on climate sensitivity is similarly tentative, but it is at the heart of the issue, and the only place you'll find on the net where someone is trying to be rigorous and rationally sceptical and enquiring.

He's doing a great job, even if he is human, and his productivity is amazing.

He is not by the way anything of an extreme sceptic. This is not CO2 Science. This is a guy who thinks it was not and is not a sensible experiment for us the species to perform, raising CO2 levels as we are. You must see that if this level of enquiry from such a background into the claims of AGW cannot be tolerated by AGW proponents, they have moved into the realm of religion not science.

If you want to give a derivation of the 2.5C sensitivity, I am all ears. He will be too. Till then, I'll continue to read CA not with belief, but with increasing interest.

Anonymous said...

Anon 2:00 AM says "

"Steve M can make mistakes. He is human."

Can and does, but that is a silly excuse if ever there was one. Pathetic, really.

The critical thing is that McIntyre claims to be an "auditor."

So he should act like one. Any auditor worth his/her salt carefully reads the material he/she is auditing.

Or perhaps we are just to accept that "Ooops I did it again" is a legitimate excuse for auditors as well as Britney Spears?

Anon 2:00 AM continues
"I do not think the record on the Hansen material is as you represent it"

RTFP. Otherwise, you just look foolish like McIntyre did.

Carrick said...

Of course, being ethical Rabetts, we used the GISS surface stations record which includes the polar regions. As we all know the models, including Grandpa Hansen, predict that the greatest warming will be in the Arctic, so if you use a surface temperature method or one of the MSU records that do not include the Arctic, it will appear that the models under overpredict

If one is to be ethical, it's important to note that global climate models also predict a warming in the Antarctic, which isn't seen. Seems like that's a pretty large feature being missed by the models.

Really though, the only meaningful test of the '88 model is to rerun them using the known patterns of forcings between 1988 and now. Why? Because the modelers weren't given the opportunity to tune the model for that period.

I'm guessing if they did, their models would come in a bit high. But that begs the question of how would the newer models with presumably better treatment of physics do, and why do we care what a 20 year old model does?

From my perspective, this episode really illustrates the problems of prognostication given the complexity of changing industrialization patterns. (Who would have predicted in 1988, that the US CO2 emissions would have flattened out and are currently in a small downward trend?)

Carrick said...

By the way here's a nice graphic showing a long-term negative trend in the Antarctic. This is from Nasa's Earth Obsevatory, in case somebody questions the neutrality of my previous link...

Also it's just a beautiful graphic.

Slevdi said...

Why are some of the anonymous posters above (or is it just one?) very snotty towards this McIntyre chap? I've read a few of his posts at CA and they seem to be very level headed. Whether they are right or wrong eludes me as I am not able to grock the jargon.

Mention of his name here - and other AGW blogs - seems to be a red rag to a bull, and I find that suspicious.

Anonymous said...

Why are some of the anonymous posters above (or is it just one?) very snotty towards this McIntyre chap?"

That's a side show.

The real question is "Why should any scientist (or anyone else) take McIntyre seriously when he is so careless with his reading of scientific papers like Hansen 88?"

coby said...

Hi Eli,

I hope you don't mind that I have embedded your nice updated ABC graphic into this post, with proper attribution of course. Email me at aDOTfewDOTthingsDOTillconsideredATgmailDOTcom or comment over there if you want something changed.

EliRabett said...

No problem:)

Srinivasan Possin said...

"As we all know the models, including Grandpa Hansen, predict that the greatest warming will be in the Arctic, so if you use a surface temperature method or one of the MSU records that do not include the Arctic, it will appear that the models underpredict." Don't you mean "overpredict"? Doesn't the GISS temperature record estimate temperatures over polar regions? What if that is correct, could you point me to an explanation of the technique.

EliRabett said...

What GISS does (and now to an extent HadCRUT) is take advantage of what are called telecommunications, e.g. that there is a strong relationship between temperatures in one place and others as far as 1200 km away at least in terms of monthly averages. Thus, even though there are not very many stations in the Arctic, one can extrapolate from them others that are not so far north up to the north pole.

The exact details and links to the underlying research on which the extrapolation is based can be found on the GISS TEMP site. The base work was done in the 1980s