Sunday, November 01, 2009

Keith Briffa REALLY Responds

Keith Briffa and Thomas Melvin have put up a comment on the use of the Yamal proxy records, and a response to McIntyre's Yamal Follies, the conclusion of which is

So what can we conclude on the basis of this and McIntyre's sensitivity tests? Does either version of the Yamal chronology as presented in Briffa (2000) and Briffa et al. (2008) present a misleading indication of the likely history of tree-growth changes near the tree line in the Yamal region over the last two millennia, or can McIntyre's "sensitivity analysis" be taken as evidence that tree growth has not increased in this region in the second half of the 20th century as is clearly implied by the "extreme" version of the Yamal chronology he produced? On the basis of the evidence we report here, the answer is very likely "NO" on both counts.

McIntyre states "If the non-robustness observed here prove out .. this will have an important impact on many multiproxy studies ...". We have shown here that the "KHAD only" example constructed by McIntyre itself represents a biased chronology, contradicted by the evidence of other chronologies constructed using additional and more representative site data. The evidence does not support a conclusion that our previous work was in any way seriously flawed. The last 8 years of our chronology ARE based on data from a decreasing number of sites and trees and this smaller available sample does emphasise the faster growing trees, so this section of the chronology should be used cautiously. The reworked chronology, based on all of the currently available data is similar to our previously published versions of the Yamal chronology demonstrating that our earlier work presents a defensible and reasonable indication of tree growth changes during the 20th century, and in the context of long-term changes reconstructed over the last two millennia in the vicinity of the larch treeline in southern Yamal.

and, oh yes, as Eli said about who owned the data
Briffa has also been attacked by McIntyre for not releasing the original ring-width measurement records from which the various chronologies discussed in Briffa (2000) and Briffa et al. (2008) were made. We would like to reiterate that these data were never "owned" by the Climatic Research Unit (CRU) and we have never had the right to distribute them. These data were acquired in the context of collaborative research with colleagues who developed them. Requests for these data have been redirected towards the appropriate institutions and individuals. When the Briffa (2000) paper was published, release of these data was specifically embargoed by our colleagues who were still working towards further publications using them. Following publication of the 2008 paper, at the request of the Royal Society, Briffa approached colleagues in Sweden, Ekaterinburg and Krasnoyarsk and their permission was given to release the data. This was done in 2008 and 2009. Incidentally, we understand that Rashit Hantemirov sent McIntyre the Yamal data used in the papers cited above at his request as early as 2nd February, 2004.

The Climatic Research Unit has never been a prolific producer of tree-ring records, focussing mainly on the collaborative analysis of data generously provided by other institutions. We will continue to respect restrictions placed upon the dissemination of data by those colleagues who provide them. All of the data produced at CRU (sampled from living oaks or pines at various sites around the UK and Scandinavia) have been provided on request. (All of the data used or produced in the analysis described here are provided on the Data page.)

Go RTFL and then go read CA if your stomach can take it. Of course, Steve interprets caution as something that he does not do.

15 comments:

Dano said...

Why would someone risk eye damage by going to CA and suffering through the chimp screeching? Please, sir. Have you no decency?

Best,

D

EliRabett said...

Not a jot

Simon D said...

I'd venture a guess that the strong language is most likely a reflection of Briffa and Melvin's frustration dealing with CA's unfiltered attacks on their research. Peer review is flawed but at least provides some filter, so the community knows whether to take a critical analysis seriously. This is what I've been arguing about on Maribo. The blogosphere permits constant online machine gun fire of critical analyses, one in which 99.9% of the bullets are duds. McIntyre's perfectly welcome to do his analyses, but he should submit for review, rather than expect scientists to respond to every one of his voluminous blog posts. If climate scientists took the time to dutifully responded quickly to every online criticism of their work, and every request for data, they'd never be able to do any research.

John Mashey said...

..."never do any research."

But isn't that the goal? I.e., the general equivalent of The Data Quality Act, especially as discussed in Chris Mooney's book.

Does Canada have any equivalent of that?

Deech56 said...

As difficult as it is to assign motive, I believe John and Simon hit the nail on the head. How many times have we faced the argument that if the data are not certain, we should take no steps to prevent catastrophic climate change? The difficulty is that even the best science is imperfect, especially when trying to use indirect or incomplete physical evidence (from tree rings to fossil bones) to reconstruct the past. It’s hard for scientists to convey nuance and uncertainty but it’s also dangerous to oversimplify. It’s especially troublesome to talk about this dilemma.

I am thinking about a recent post in CA in which Rob Wilson explained the choice of proxies used in D’Arrigo, et al. 2006. The upshot from the discussion (and the rest) is to throw doubt into the northern Eurasia studies, and that any studies or reports that used these are also suspect. The multiple lines of independent studies that show the iconic sports implement become a series of flawed studies by the Team and from which we can conclude nothing.

The trap is that all of climate science gets boiled down to the hockey stick (better than broiled hockey puck, I guess), and any attempt to put these observations into scientific context almost becomes an admission of defeat. Debating the scientific merits becomes closing ranks. Debating the benefits of peer-review becomes a discussion about the greatness of blog review, since it’s these blogs that are heroically catching the errors and defying the Team. Of course, the truly scientific blogs are suspect.

And it’s only going to get worse in the coming months.

Anonymous said...

..."never do any research."

But isn't that the goal?"


McIntyre DOES seem to be on a "crusade" to see to it that Mann is forced out of science and forced to "never [again] do any research'

While it is true in a specific sense, I don't think it necessarily applies in the general sense, though.

For example, I don't see the evidence that McIntyre is out to bring a halt to climate research in general (although that probably IS the goal of people like Inhofe)

Steve Bloom said...

Deech56, so often it's forgotten that late Holocene climate is nearly policy-irrelevant since we can't (yet, anyway) derive climate sensitivity from it.

The stuff that needs to be in the public spotlight is the (mostly)recent science (starting with Hansen et al's "Target CO2") pertaining to temperatures, CO2 levels, and ice sheet state during the warm parts of the Pliocene and Miocene, and the fact if we let CO2 levels get much higher the planet will return to those conditions. Sure there's uncertainty about the timing and some other details, but the big picture is crystal clear.

To my knowledge McIntyre has never looked at this stuff, which is peculiar since you'd think he'd want to work on something with actual important implications. There's certainly no shortage of "audit"able papers and data.

Rattus Norvegicus said...

It's Keith Briffa, not Kenneth Briffa.

But he did destroy McIntyre.

Deech56 said...

Steve Bloom, your comment actually brings up an important point - that the key number is climate sensitivity. It also sent me back to the recent Knutti & Hegerl review article (h/t to John Cook, who has an excellent series of posts up), where it does appear that the sensitivity based on the millennial data falls at the lower end of the range.

One would think that the recent Linzden and Choi paper would create some stir, and would be cited as evidence more often. (Instead, I have been subjected to a David Archibald analysis.)

Judging from how much the hockey stick is revisited, it must have some kind of iconic status, maybe because the critics can point to the Wegman and NAS reports. It is tempting, though, to question why the NAS is suddenly a reliable source of information.

The Wegman report is especially useful to he denial crowd since it undercuts the independent verification of results by claiming that the researchers are not independent. No skepticism applied to this stuff! No sirree.

Anyway, back to your point - under BAU, we will hit a doubling pf pre-industrial CO2 levels around 2050 and a quadrupling by 2100. It's easy to do the math for a sensitivity of 3°C. This alone should alarm us.

Marion Delgado said...

My opinion of the denialists nowadays is mostly unprintable.

I'd actually say Lindzen is the only one left who's sort of playing the science game.

Marco said...

Seriously, Marion, Lindzen? I'd put John Christy waaaay higher on the list. Lindzen has been the one arguing that he did not want to use corrected data because he simply could not accept so much corrections were always in the direction of more warming. Lindzen also loves to show up at the Heartland conferences, where John Christy declines to be seen for fear of being grouped with the crackpots that show up there (or so I have been told).

Andrew Dodds said...

Deech56 -

Actually, even a warming of 2K puts us outside anything we have seen since the interglacial/glacial cycle started several hundred thousand years ago; this is more than alarming since we are essentially assuming that there are no 'rakes in the grass' out there.

Marion Delgado said...

Marco, I'll take your response to heart and re-consider.

Tentatively, I just don't see what positive steps Christy takes - it all seems fairly verbal and interpretive. I should probably add several others, not G&T but everybody on the competent side of them.

Deech56 said...

Andrew Dodds, you make a very good point, and your observation is what makes me doubt that we will have BAU. By mid-century our choices will be made for us.

MikeN said...

And why is it that Trans B requested Briffa provide this data?

Because it was part of their policy that such data should be released as a matter of science. Steve McIntyre was the one who pointed that out.
Briffa could have gone to his colleagues in the past and made this request.