Philip

The response of non-linear systems to forcing is not straightforward. Many people think it's likely that a portion at least of 20th C warming is due to some non-linear response.

If one argues for a non-linear response to modest changes in RF (TSI variation) surely this is also an argument against an insenstive climate system?

It's not clear what caused the MWP and LIA, although the general view is that both may have been climate responses to variations in TSI. These variations were not, apparently, very large.

If climate exhibits non-linear responses to minor changes in RF, then presumably it must be sensitive to increased RF from CO2?

To be clear, I'm not suggesting that CO2 will trigger a non-linear response in temperature as you suggest that the mystery forcing may have done in the early C20th. But I am suggesting that climate sensitivity to doubled CO2 (or the equivalent increase in RF) will be in line with the best current estimate of ~3C. Any lower, and variation like the MWP/LIA could not happen. Nor would the spatial and seasonal reorganisation of RF by the 100ka Milankovitch cycle be sufficent to terminate a glacial.

Yet I suspect that you are suggesting that the role of CO2 in C20th warming is being over-stated and implying that projected warming may be exaggerated as a consequence. Certainly there are many who believe this to be the case, even if I've over-interpreted what you write. This seems to me to be a contradictory position. Do you see why I'm puzzled here?

It's fascinating how this is almost turning the literature argument on its head. MBH98/99 try to get rid of the MWP. S&B03 tries to restore it. Both are flawed, both are the product of determination to impress a message on to the public and policy makers. But there is a rather amusing irony: there was an MWP. Whether global average temperatures ever got above mid-C20th levels is debatable. But MBH were wrong. Yet their paper is self-contradictory: a long, straight handle on the stick implies a low CS. Why then should we expect a significant response to increased RF from, for example, CO2? In contrast, S&B say, look: lots of natural variability. This argues for a high CS, including, presumably, to increasing RF from CO2 ;-)

Before I forget, who are the 'many people' you refer to who think that at least some of the early C20th warming was a non-linear response to an unidentified (?) forcing?

Bish,
From writing:

On the other hand, the review process at CR was formally in order.

von Storch went to this:

The review process had utterly failed; important questions have not been asked, as was documented by a comment in EOS by Mann and several coauthors.

Kinne himself details why he objected to von Storch's unilateralism at Climate Research, even as von Storch and he, wrestled with the foisted impression that the community had found processes at CR to be 'flawed'. As ever, the community only consisted of a handful of people gossiping on emails: Mike Hulme, Barrie Pittock, Jim Salinger, Mike Mann and Phil Jones. (emphasis mine)

From Kinne's article (Climate Research: an article unleashed worldwide
storms

Hans von Storch has done more than most other members of the CR Editorial Board. Since 1994 he has increasingly been a powerful motor promoting the journal’s development. CR has been close to his heart. I am very grateful to him and recently appointed Hans as CR Editor-in-Chief (EiC). He accepted as of August 1, drafted an Editorial and proposed that all mss be submitted to him. His Editorial text draft has drawn both positive and negative responses from editorial board members. It was criticized that the EiC’s functions as proposed by Hans would amount to a devaluation of editors and reviewers.

Hans’ proposal could not assure unbiased high quality ms selection in view of the widely diverging expertises of authors, reviewers and editors. Further Hans made several statements that did not represent the views of all editors; he did not consult with several editors while speaking in their names.I wanted the editorial by Hans von Storch to be published, but with a green light from the Editorial Board. Hence I asked Hans not to rush the editorial, to consult with the Editorial Board and to publish a revised version. Hans did not like this and decided to resign only a few days after I had appointed him.

So, the resignation from von Storch is a bit of an ego tiff, and a protest by von Storch against his politicizing move (publishing an editorial just in time for a US Senate hearing) being prevented. Kinne did want to publish the editorial.

The apparent methodologic flaws which persuaded von Storch that the 'overall review process' had a problem even as the 'formal review process' was in order, as McIntyre points out, are present in Mann's own rebuttal paper which formed the very basis for von Storch's opinion.

BBD

Just to be clear from your last posting: you accept there (likely) was a MWP, and that it was widespread around the globe?

You argue it was likely caused by an increase in TSI. While modern warming is almost certainly down to RF from CO2. (?)

This, you say, argues for a high CS.

But that's cherry-picking, BBD. What of the rest of the last 1000 or so years, subject to various forcings and exhibiting substantially less, or no, sensitivity?

Gixxer

Apologies - I have been travelling. I will try and answer your questions as soon as I get some peace... Next couple of hours hopefully.

Gixxer

But that's cherry-picking, BBD. What of the rest of the last 1000 or so years, subject to various forcings and exhibiting substantially less, or no, sensitivity?

I haven't explained this properly. Sorry. If you know some or most of this already just skim. I'm trying to cover all the bases.

Start with the idea that 'global warming' or cooling is a way of measuring how much energy there is in the climate system. Energy comes from the sun as shortwave radiation. Absorption and re-radiation of outgoing longwave radiation by GHGs including water vapour within the atmosphere slows down the loss of energy to space. This causes energy to accumulate in the climate system. That's why it isn't -15C at night even at the equator.

The balance between incoming solar SW and outgoing LW determines how much energy accumulates in the climate system (mainly in the oceans). This determines if the CS warms, or cools.

Both solar SW and outgoing LW are terms of radiative forcing (RF). At the end of the day, it's all just energy. So there's no essential difference between a variation in solar output or in the amount of GHGs in the atmosphere. Both change the amount of RF experienced by the climate system. Both will cause it to heat up or cool down. The temperature response to a defined change in RF is described as the climate sensitivity.

The point here is that the climate seems to be moderately sensitive. Quite small changes in solar output appear to have caused the MWP and LIA (the latter is clearly associated with the period of slightly reduced solar activity known as the Maunder Minimum).

Nothing much else appears to have varied over the last 1000 years or so. No cherry-picking or repeated alterations of climate sensitivity are required. When something (probably the sun) did change a bit, we got an MWP and later an LIA.

In the here and now there's a great deal more CO2 about, and RF from same is rising. Since everything indicates that the climate is moderately sensitive to modest changes in RF, there is a near-certainty that it will respond to an increase in RF from CO2 by warming up.

A favourite argument of contrarians is that the climate sensitivity is low. But if it was, there wouldn't be much in the way of climate variation, even if forcings varied quite substantially.

Thanks for that BBD, a very clear explanation. (I was largely familiar with what you have set out.)

Indeed it is ironic that Mann and his mates have tried so hard to erase the MWP if it supports a magnitude of climate sensitivity equating to their claims.

Gixxer

Glad it was clear; sorry about the inevitable re-hash of what you know.

The 'straight handle HS contradiction' only dawned on me last night. But it still works today ;-) so maybe there's a decent point there. I've a feeling that some here might have mistaken me for an apologist for Mann. But as you can see, I'm not.

Try it out me on the other discussion thread later - I won't care if it goes a bit wrong

Ye gads! I think it worked - thanks BBD!

BBD says: The 'straight handle HS contradiction' only dawned on me last night.

Are you serious? There must be some explanation, because it sounds like a flat-out lie otherwise.

Here are you own words arguing the same essential point about five months ago:

"As these arguments grind on, I find myself wondering why nobody is asking the obvious question about the MWP. Namely that whichever attribution one favours, the actual forcings and feedbacks suggested are not especially large (eg increased TSI, decreased volcanism, NA warm water). Which is strongly suggestive of a relatively high climate sensitivity.

So, arguing for a pronounced, global MWP (which the evidence appears to support) is arguing for a high climate sensitivity. This is not compatible with 'lukewarmerism' which is one of several reasons that I have had to abandon this position recently. With considerable regret, but that's how it goes."

Shub

Now you are calling me a flat-out liar for saying the same thing twice, in two different contexts?

I'm left shaking my head in amazement, once again.

FWIW, on this thread, I was thinking specifically about this as a critique of MBH98/99. It reveals an internal contradiction in Mann's reasoning that hadn't struck me before, although it is blindingly obvious in hindsight.

Yet instead of agreeing that yes, this does look like a valid criticism of MBH98/99, you call me a liar. Doesn't that strike you as slightly deranged?

Shub -
Between 800-1300 there was relatively high solar activity. I don't suppose you know how this has been incorporated into climate models?

I have only glanced at this thread, and among the early postings was struck by these two short sentences posted (with some emboldening that I cannot reproduce) by BBD on Dec 8 at 2:55 PM

" Neither Soon nor any other player has taken legal action. Therefore these facts are correct."

I'm afraid that I don't have the time or the inclination to read the whole thread, so it's possible that someone else has already drawn attention to this absurd non sequitur.

So Cassio, you would allow Greenpeace - an easily identifiable organisation - to post defamatory and misleading information about your affiliations and sources of funding and do absolutely nothing? Not even a rude letter from your lawyers? These are Americans, let us not forget.

But have no fear. Soon admitted that it's all true anyway:

Soon, who had previously disclosed corporate funding he received in the 1990s, was today reportedly unapologetic, telling Reuters that he agreed that he had received money from all of the groups and companies named in the report but denied that any group would have influenced his studies.

Yeah, right.

So, where's this 'absurd non sequitur' then?

Lots of waffle, plenty of abuse from the usual suspects, and no answers to these questions as yet. Much diversionary chatter about S&B. No focus on the real issues.

Let's have them up again for the new page:

- The real question is whether the MWP is relevant here. This presumes equivalence with the present. Can we assume this?

- If you argue yes, there is a condition. The MWP seems to have been caused by increased TSI. So is there credible, widely-accepted evidence that TSI is the main driver of modern warming?

- A substantial body of work points to increased radiative forcing by CO2 as an energetically sufficient cause for much recent warming. Has it been refuted or even seriously challenged?

- Have observations revealed any energetically sufficient alternative?

- If they did, the effect of increased RF from CO2 would still have to be taken into account. If 'something else' is responsible for modern warming, it should be warmer than it is. How do you explain the missing heat?

- S&B and the small group of energy-industry funded, right-wing contrarians they belong to has deliberately and successfully distracted attention from the central issues. For example, if the hockey stick is debunked, what effect will it have on the laws of physics that cause RF from CO2 to heat the climate system?

The MWP seems to have been caused by increased TSI.

Only if you can show conclusively that high solar activity had nothing to do with the relative warming.

Soon also said

"I have never been motivated by financial reward in any of my scientific research," he said. "I would have accepted money from Greenpeace if they had offered it to do my research."

(and I have no reason to disbelieve him).

matthu

Only if you can show conclusively that high solar activity had nothing to do with the relative warming.

Sorry, you've lost me there. What are you trying to say?

(and I have no reason to disbelieve him).

I've got over a million reasons why I don't believe him at all.

If you cannot show conclusively that high solar activity had nothing to do with the relative warming over the MWP then there is no reason to presume that it was caused by e.g. TSI.

Are you saying that one has to prove that solar variation did not cause the MWP before it is allowable to argue that it probably did cause it?

And if not solar variability...? We're back to the 'mystery forcing'. A touch of Occam's razor might be appropriate here.

Solar activity is a different concept to TSI (one that was not considered in AR4).

matthu

Solar activity is a different concept to TSI (one that was not considered in AR4).

Fine. We can go with subtle, solar-cloud effects. What we need is good evidence that this is a significant factor in modern warming.

Same goes for jet stream-UV interactions.

We also still need a moderately sensitive climate system or nothing much would happen anyway.

During this discussion of mystery forcings, uncontroversial estimates of RF from CO2 disappear from the table. Odd.

We also still need a moderately sensitive climate system or nothing much would happen anyway.

I am not convinced that this follows logically, unless you discount all possible interactions other than really simple relationships. That is what resulted in only TSI being considered in the first place.

Lots of waffle, plenty of abuse from the usual suspects, and no answers to these questions as yet. Much diversionary chatter about S&B. No focus on the real issues.

Please, sir, the title of this thread is

Soon, Baliunus (sic), de Freitas, Etal

Just in case you hadn't noticed.
Now it's quite possible that you'd rather not discuss that subject but that is the subject. So it looks as if the waffle and certainly the abuse are coming from you.
If you don't want to discuss the problems that Soon and Baliunas and de Freitas experienced at the hands of Mann and his little band of yes-men why don't you go and talk about what you want to talk about somewhere else and leave us to our own games?

matthu
I see no reason to disbelieve Willie Soon either. At least so far I have seen no evidence that he deliberately falsifies data, uses statistical methods known to be at best flaky, or bullies other scientists into making sure he gets his own way.

Hi BBD,
Re my last comment: I didn't call you a liar. I was just as surprised as you say you were, when I saw your comment so I asked. I think it is a natural reaction if one says something and says (more or less) the same thing 5 months later and yet claims the idea dawned on him just the day before.

Moreover, you say: "FWIW, on this thread, I was thinking specifically about this as a critique of MBH98/99. It reveals an internal contradiction in Mann's reasoning that hadn't struck me before, although it is blindingly obvious in hindsight. "

You can critique Mann like that, only if you'd had knowledge that the climate system does have high sensitivity a priori. Otherwise it sounds just like adoptiong a position and then attacking evidence that does not fit with that position.

Contrary to your constant refrain, not only is climate sensitivity just defined w.r.t to CO2 (presumably to guide 'policy'), it actually has a distinct physical basis in the climate system as well. x W/m2 of radiative forcing of solar origin is quite different from x W/m2 forcing by increased CO2 conc. mediated greenhouse effect. In fact in some respects it is quite the opposite.

What the hockey stick did was answer this question. CO2 concentrations are at levels historically never matched before, so what do the temperatures correspondingly do? de Freitas' email contains a good summary of the IPCC TAR logic.