First time commenter – sometime lurker.

That was a really enjoyable read. Don’t think it really changed anyone’s mind or belief systems and certainly didn’t stay on topic, but it was fun.

Just a query and an observation: why is there so much arrogance and oftimes aggressioninvolved in AGW discussions? It’s only the weather ;o)Predominantly on the pro side you get,
“I’ve said this before and I’m not saying it again” “I told you” etc etc?
It reminds me of talking to an untrustworthy/incompetent/lazy supervisor. And on the con, you have people loaded for bear with every factoid a mere keystroke away, reminding me of suspects in an interview grasping at every straw trying to convince the copper they aren’t to blame.

Interesting.

Savo

Sure thing. Are you going to contact Robinson, Robinson and Soon and tell them their lag argument is nonsense?

I agree that the ice core data did not show the relationship as clearly as it now does (and always have). I also agree that the lag is not inconsistent with AGW, which you want to call “does fit”. I always have agreed it is not inconsistent (i.e. does not contradict) and said so above.

As for the lag itself, it does fit in with AGW. This is not in dispute in the serious literature, but only in the denialist realms. But feel free to find me a paper that says otherwise.

Barnola et al (Tellus 1990) is: J. -M. BARNOLA P. PIMIENTA D. RAYNAUD and Y. S. KOROTKEVICH, CO2-climate relationship as deduced from the Vostok ice core: a re-examination based on new measurements and on a re-evaluation of the air dating Tellus B 1990. Manuscript received 22 January 1990; in final form 10 July 1990). The abstract says:

Interpretation of the past CO2 variations recorded in polar ice during the large climatic transitions requires an accurate determination of the air-ice age difference. For the Vostok core, the age differences resulting from different assumptions on the firn densification process are compared and a new procedure is proposed to date the air trapped in this core. The penultimate deglaciation is studied on the basis of this new air dating and new CO2 measurements. These measurements and results obtained on other ice cores indicate that at the beginning of the deglaciations, the CO2 increase is either in phase or lags by less than about 1000 years with respect to the Antarctic temperature, while it clearly lags the temperature at the onset of the last glaciation.

The realclimate claim under discussion is that Hansen “predicted” this lag, a claim made at
http://www.realclimate.org/ind.....-and-co2/) as follows:

Second, the idea that there might be a lag of CO2 concentrations behind temperature change (during glacial-interglacial climate changes) is hardly new to the climate science community. Indeed, Claude Lorius, Jim Hansen and others essentially predicted this finding fully 17 years ago, in a landmark paper that addressed the cause of temperature change observed in Antarctic ice core records, well before the data showed that CO2 might lag temperature. In that paper (Lorius et al., 1990), they say that:”changes in the CO2 and CH4 content have played a significant part in the glacial-interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the relatively weak orbital forcing”

The lag is clearly discussed in Barnola et al 1990, which was published before Lorius et al 1990 and is cited by it. The RC claim that Lorius et al 1990 was written “well before the data showed that CO2 might lag temperature” is untrue and the conceit that Hansen “predicted the lag” is an inflation of Hansen’s record.

There may not have been an obvious lag between CO2 and temp then (1990)

That said, the lag in the empirical data was discussed at the Liege Colloquium which appears to have taken place in June 1989. Since conferences generally require people to send in abstracts a few months before the conferences, it’s likely these empirical observations was know at least several months prior to the conference.

Take two steps back a moment. Disregard the spurious temperature reconstructions (Hockey Stick) that appeared to show a good correlation with 20th century CO2 and disregard the initial Hansen prediction that temperature rises were directly caused by CO2 from the Vostok ice cores. Now lets think about CO2 and AGW

1) Near solar planetary temperature is related to a few basic things: Stellar output, land albedo, atmospheric constituents. Also the existence of a magnetic pole. So ask the first obvious question: how do solar cycles relate to temperature changes.
I know that there is the Gleisberg 70-100 year oscillation and the longer Suess 200 year cycle. So when I look at the temperature anomaly of the NH I see a slow increase in temp from 1890 odd til today with what would appear to be a sharper increase in the last 30 years but I’m not sure. What I can say is that my first impression is that there looks to be something periodic happening. Additionally there is superimposed on this a min to min cycle from around 1900 to 1980. Okay this may not be anything and it may be a willingness/bias of mine to only assume the sun is causing heating but until I am completely convinced that it isn’t I do not rule it out. The data has too much uncertainty still when I delve into the measurement and analysis techniques.

2) There may not have been an obvious lag between CO2 and temp then (1990) but its pretty much widely known now that there is so ask the obvious question: how can CO2 cause the temp to increase if it only increased much later and how come the temp goes down first then the CO2 goes down? I’ll try and answer

This would imply there is an initial low CO2 concentration that remains unchanged but causes a positive feedback in the atmosphere (H20 etc). Temp rises. Then the CO2 starts going up which should increase the positive feedback even more so temp should go up even more but no it looks like some other process (maybe even related to the CO2 itself) is causing the temp to limit and then have a net negative feedback even though you may think that the strength of the CO2 feedback based on the initial CO2 level should cause it to increase. This negative feedback dominates so that the CO2 (even at higher levels) is not affecting temperature. CO2 levels decrease again with no effect on temp until they hit the low level again some 800 years after temp has hit a minimum. Then this value of CO2 causes the temp to rise. I guess a bit like having the right amount of air mix in your carburetor. Its an interesting idea and certainly feasable however it implies that there is a threshold.

So the question is then if this is the mechanism it would only cause the temp changes if it had a positive feedback below some threshold then a negative feedback effect above the threshold. The CO2 itself would act like a limiter. Does this occur in the lab or on other planets with large amounts of CO2? And where exactly is the present CO2 level in relation to this threshold if this were the case.

On the other hand an alternative idea would be that CO2 has little significant effect on climate as opposed to solar variations, albedo changes, clouds even.

The question for CO2 is can these two ideas be resolved with the current data sets. I haven’t seen it yet. Too much uncertainty. So I cannot then say that there is AGW and I can’t see how anybody else can. I have to say that I don’t know. Because I’m a scientist and my first job as a scientist is to speak the truth as best I know it and show why I believe it to be so.

The full article is here:
http://articles.adsabs.harvard.....6.000.html

“Are you suggesting ice cores prior to 1990 are a mythical?”

Why don’t you try rereading what I said? I never said there weren’t ice cores.

I read what precisely what you said. You said this.

But you keep claiming–with no evidence whatsoever–that there was some mythical ice core data before 1990.

Based on that, I asked you if you were suggesting ice cores did not exist before 1990. How was I supposed to know you were referring to ice cores with some particular level of resolution?

I am aware that much earlier you said something about resolution increasing with time. So what the heck does that have to do with any points I made?

What’s important is that the theory explaining the lag is perfectly consistent with AGW–despite what denialists such as Robinson, Robinson and Soon would have you believe.

Why is this “what’s important”? And in what context?

I don’t see how that is remotely the important thing in terms of the discussion we are having in comment here. This discussion was triggered by your claim that some the positive feed back theory for the CO2 lag is “obvious”. It is true that if your theory is “obvious”, then RRS claim is obviously wrong.

However, I am telling you your theory is only plausible not obvious. There are a sufficient number of holes the empirical support for your theory to permit the possibility that the alternate theory that temperature causes CO2 to be released but there is no positive feed back due to CO2 causing a noticeable temperature rise.

I haven’t suggested your alternate theory for the CO2 temperature relationship is implausible or wrong. It is consistent with– as are other theories.

I’m unimpressed by the claim that Hansen ‘predicted’ the lag in the CO2 Vostok cores because we had CO2 and temperature data from Vostok cores before he made it. It’s true that the resolution improved– but so what? People learn things and infer things based on low resolution data. If Hansen had had higher resolution data, maybe his “prediction” of the time lag wouldn’t have been off by orders of magnitude!

What’s important is that the theory explaining the lag is perfectly consistent with AGW–despite what denialists such as Robinson, Robinson and Soon would have you believe.

And we return to square one. That remains an assertion by you rather than a statement of fact. I believe it is correct, but you have never cited anything that amounts to proof.

Why don’t you try rereading what I said? I never said there weren’t ice cores. I said the ice cores didn’t have the resolution to definitively say if CO2 lagged temperature. Drilling techniques improved a lot in the 1990s, as well as methods of analysis and the handling of the cores themselves.

But if you want to keep believing that every ice core is the same then that’s fine with me. The prediction is not particularly important anyway. What’s important is that the theory explaining the lag is perfectly consistent with AGW–despite what denialists such as Robinson, Robinson and Soon would have you believe.

There were no ice cores drilled that showed a lag between 1985-1990. Feel free to prove me wrong if you find one.

I didn’t say there were any ice cores drilled between 1985 and 1990. Why would I try to prove there were any such ice cores? (That said, I don’t know what was drilled at what particular time. The issue is when information became available to the person’s who are “predicting” something.)

Not what I said at all. It was clear that temp and CO2 had a relationship in 1990–they rose and fell together. But it was not clear which came first

I have been discussing what empirical evidence Hansen already already knew when he made what you call a “prediction” which you seem to credit as showing his theories or ideas have some sort of predictive power.

If the empirical data were already available to him– or his co-author Lorius, they are not predicting what empirical data would ultimately show based on theory. They are “predicting” what empirical data would show based on what the empirical data already have revealed to them.

Those empirical results might have be preliminary or coarse, but the empirical data were affecting their “theory” and in particular the “predictions” of what the data would show. (Which they should btw. That’s the scientific method since Bacon.)

But you keep claiming–with no evidence whatsoever–that there was some mythical ice core data before 1990.

First, whatever are you talking about?

Are you suggesting ice cores prior to 1990 are a mythical? Besides the 1985 paper by Lorius already mentioend above, here’s:

“Vostok ice core provides 160,000-year record of atmospheric CO2
paper presenting results of CO2 analyses on ice cores. It’s published in 1987. ”
http://www.nature.com/nature/j.....408a0.html

This is not only a non-mythical ice core but an ice core from Vostok. Moreover, CO2 results were presented. One of the authors is Lorius, who three years later coauthored the paper in which you tell us Hansen “predicted” that temperature would lag the CO2.

By the way, paper cites “Record of past atmospheric carbon dioxide from tree-ring and ice core studies” published by Lorius, Hansen’s co-author in 1982!

I hope you consider a journal article in Nature evidence that ice cores predate 1990.

If you weren’t to busy to google, you might find these Boris. I did “Lorius Hansen vostok” in Google Scholar, and there it was.

Patrick,
It’s my understanding that the longish delay (And it’s no really clear form the data what the delay is–500, 800, 1000) is related to the carbon pump–with which there are still major uncertainties. I don’t see how the mechanism of carbon release matters much to sensitivity–at least on the long term–or how it would matter to the 20th century, where the source of carbon is well known and understood.