Rob W in the Courier

While I was away, there was a bit of a kerfuffle over the new paper by Esper et al. The authors claimed that Northern European temperatures were warmer than today in both the Medieval and Roman Warm Periods. Anthony reported the story at the time.

The kerfuffle came over subsequent newspaper claims that the paper disproved the AGW hypothesis (I haven't seen these claims myself, but no doubt they are out there). Readers may therefore be interested to see the response of Rob Wilson, one of the co-authors of the paper and an occasional commenter here, in his local newspaper, the Dundee Courier.

Some climate change sceptics have leapt on this as proof global warming does not exist, but Mr Wilson said no such conclusion could be drawn from a study which concentrated on one geographic area.

He said it has become ''expected'' people on both sides of the climate change argument will seize on certain parts of research to back up their own arguments, ignoring other data does not support their conclusions.

''It can come from both sides and I think there will be a few climatologists on the other side who will find issue with some of our findings,'' he said.

However, he made it clear the study does not disprove rising temperatures since the start of the 20th century are down to the actions of humankind.

I make a similar point myself in the Hockey Stick Illusion. Current temperatures can be entirely precedented and the AGW hypothesis could still be true. Equally, temperatures can be unprecedented and the hypothesis could be false.

That said, if temperatures do turn out to be nothing out of the ordinary (and I don't think we know either way yet), then it does rather reduce the cause for immediate alarm.

Gergis to resubmit at end of July

The University of Melbourne's page on the Gergis paper has been updated:

An issue has been identified in the processing of the data used in the study, "Evidence of unusual late 20th century warming from an Australasian temperature reconstruction spanning the last millennium" by Joelle Gergis, Raphael Neukom, Stephen Phipps, Ailie Gallant and David Karoly, accepted for publication in the Journal of Climate. 

The authors are currently reviewing the data and methods. The revised paper will be re-submitted to the Journal of Climate by the end of July and it will be sent out for peer review again.

I do think that this time around the Journal of Climate should ask the authors to archive the data series that didn't pass the screening as well as those that did.

A problem with the AGW hypothesis

A paper published in Nature last week claims that 12 million years ago the sensitivity of the Earth to carbon dioxide was profoundly different, with very high temperatures maintained despite very low levels of the bogeyman gas.

Deep-time palaeoclimate studies are vitally important for developing a complete understanding of climate responses to changes in the atmospheric carbon dioxide concentration (that is, the atmospheric partial pressure of CO₂, p_co2)¹.

Click to read more ...

David King has the answer - central planning and more spending

Former Government Chief Scientific Adviser Sir David King is interviewed in the Guardian. Here are some excerpts:

Record gold prices are an indication that investors are fleeing to safety because they do not feel governments are providing the necessary long-term regulatory frameworks or incentives to give them the confidence to invest in emerging new technologies.

The Treasury civil servants are heavily driven by traditional dogma that we do not support winners but let them emerge in the market place. This is one time when we can no longer let this philosophy dominate and that is a tremendous job to be done.

The scientific community felt very battered by the University of East Anglia climate revelations but they continue to beaver away showing predictions for the next 20 years ago are even worse than predicted and we are faced with a human existential crisis.

Given King's former willingness to mislead the public, it's hard to attach much credence to his views. What is a surprise is that any reputable newspaper should give such a man any column space.

Latercomers

A couple of new stories on the Gergis affair may be of interest to readers - Andy Revkin here and Retraction Watch here.

Update on Jun 12, 2012 by Bishop Hill

McIntyre has sent the following comment to Revkin via email. (AR has posted it in the comments).

By framing a Climate Audit discussion as extended peer review, you can perhaps see why demands that I produce my own reconstruction are off point to the criticisms. Climate Audit is a form of extended peer review and criticism.

The criticisms that I’ve made have nearly all been the sort of questions that, in my opinion, a properly informed peer reviewer should have asked. For example, the Yamal dispute that you covered a couple of years ago, was an extended peer review issue. I asked why the authors did not use the site selection method in the Yamal area that they had used in the Avam-Taimyr area. Had a peer reviewer understood the methods well enough, he ought to have asked that question. It was a good question at the time and remains a good question.

If the authors had responded – as CRU and Real Climate did – saying , Nyah, nyah, we can get Hockey Sticks some other way – the reviewer and editor would have concluded that the authors were deranged. This sort of question should be answered on its own terms – as Karoly appears intent on doing.

The same things apply to the ongoing Mann debate. The technical “peer review” points were never answered. Instead, the topic gets changed to – We can get Sticks some other way; or Sticks don’t matter.

Although “peer review” is apparently an integral part of academic publishing, there is astonishingly little empirical study of peer reviews themselves because the documents are not available. Most academic discussions tend to be programmatic and platitudinous: that it’s flawed but it’s the best alternative.

I try to avoid generalities. In practical terms, if reliance is to be placed on academic articles for policy purposes, people need to recognize what isn’t done in journal peer review: no review of data, no detailed review of methodology. It is evident to me that academics need to accommodate “extended peer review” by archiving of data and meticulous documentation of procedures (source code is an aid to this, though too often sneered at.) The hypocrisy of academics expecting large-scale policy changes while refusing to provide data on the grounds of “intellectual property rights” is risible and deserving of the contempt of the public.

BTW the problems in Gergis et al are no worse than Mann et al 2008, which should have been retracted for its use of contaminated upside-down data for his centerpiece no-dendro reconstruction. By conceding the problem, Karoly and Gergis have suffered some loss of reputation, while Mann’s obfuscation has been extremely successful within the field. It seems unfortunate that people suffer for doing the right thing and are rewarded for the wrong thing. (But not the only place in the world where this happens.)

Cheers, Steve

Gergis paper disappears

Paul Matthews has just drawn my attention to the page for the Gergis et al paper at the AMS Journal website, which now displays a notice as follows:

The requested article is not currently available on this site.

Is this significant I wonder?

Update on Jun 9, 2012 by Bishop Hill

Steve M reports that the paper has been "put on hold".

Another Hockey Stick broken

Updated on Jun 7, 2012 by Bishop Hill

There are some important findings at Climate Audit today. Once again I have tried to set out a layman's version of the discussion there.

One of the perennial problems with temperature reconstructions has been a lack of data covering the southern hemisphere - the Hockey Stick itself was a northern hemisphere reconstruction, although the IPCC billed it as global in extent. However, a recent paper by Gergis et al sought to partially remedy this by presenting an Australasian temperature reconstruction for the last millennium, based on 27 proxy records, primarily from tree rings and corals. The headline was, perhaps not unexpectedly, that late twentieth century warming was unprecedented:

The average reconstructed temperature anomaly in Australasia during A.D. 1238–1267, the warmest 30-year pre-instrumental period, is 0.09°C (±0.19°C) below 1961–1990 levels.

Click to read more ...

Joelle Gergis talks up her results

Further to the last post, I came across this recent interview with Joelle Gergis, in which she discusses her recent paper. It's remarkable to see her making the same claims of hockey-stickdom that have caused so much of a furore over the last 15 years or so.

When you realise that the whole thing is based on a logical fallacy, it's hard not to become angry. [Update: but see caveats on the update to the earlier post.

Tim Osborn responds to the Yamal furore

I've just noticed that UEA has posted a response to the recent flurry of postings about Yamal, both at Climate Audit and here.

It's authored by Tim Osborn and can be seen here.

Yamal in the National Review

Harold Ambler and I have written a joint piece for the National Review about the Yamal affair.

Read it here.

Rand Simberg reviews the Yamal story

Rand Simberg at PJ Media reviews the Yamal story, quoting extensively from yours truly.

But at a minimum [Yamal] should be the final blow to the hockey stick, and perhaps to the very notion that bristlecone pines and larches are accurate thermometers. It should also be a final blow to the credibility of many of the leading lights of climate “science,” but based on history, it probably won’t be, at least among the political class. What it really should be is the beginning of the major housecleaning necessary if the field is to have any scientific credibility, but that may have to await a general reformation of academia itself. It would help, though, if we get a new government next year that cuts off funding to such charlatans, and the institutions that whitewash their unscientific behavior.

RealClimate on Yamal

Gavin Schmidt has issued the official response to the recent excitement over Yamal. I have to say, even on a brief glance through it is a wild piece of writing.

Briffa, as we know, reprocessed data from Hantemirov and Shiyatov in his 2000 paper on Yamal. He used the same data again in his 2008 paper on regional chronologies. Schmidt says:

McIntyre is accusing Briffa of ‘deception’ in stating that he did not ‘consider’ doing a larger more regional reconstruction at that time. However, it is clear from the 2000 paper that the point was to show hemispheric coherence across multiple tree ring records, not to create regional chronologies. Nothing was being ‘deceptively’ hidden and the Yamal curve is only a small part of the paper in any case.

Click to read more ...

A whole new bias

A new paper by Brienen et al in the journal Global Biogeochemical Cycles suggests that there may be a whole new set of biases in tree ring studies.

Tree ring analysis allows reconstructing historical growth rates over long periods. Several studies have reported an increasing trend in ring widths, often attributed to growth stimulation by increasing atmospheric CO₂ concentration. However, these trends may also have been caused by sampling biases. Here we describe two biases and evaluate their magnitude. (1) The slow-grower survivorship bias is caused by differences in tree longevity of fast- and slow-growing trees within a population. If fast-growing trees live shorter, they are underrepresented in the ancient portion of the tree ring data set. As a result, reconstructed growth rates in the distant past are biased toward slower growth. (2) The big-tree selection bias is caused by sampling only the biggest trees in a population. As a result, slow-growing small trees are underrepresented in recent times as they did not reach the minimum sample diameter. We constructed stochastic models to simulate growth trajectories based on a hypothetical species with lifetime constant growth rates and on observed tree ring data from the tropical tree Cedrela odorata. Tree growth rates used as input in our models were kept constant over time. By mimicking a standard tree ring sampling approach and selecting only big living trees, we show that both biases lead to apparent increases in historical growth rates. Increases for the slow-grower survivorship bias were relatively small and depended strongly on assumptions about tree mortality. The big-tree selection bias resulted in strong historical increases, with a doubling in growth rates over recent decades. A literature review suggests that historical growth increases reported in many tree ring studies may have been partially due to the big-tree sampling bias. We call for great caution in the interpretation of historical growth trends from tree ring analyses and recommend that such studies include individuals of all sizes.

Presumably, this new source of bias applies just as much to tree ring studies where the increase in growth is ascribed to temperature.

(H/T Hockey Schtick)

MSNBC on Climategate and the inquiries

There is a very interesting, if rather toe-curling, segment about Climategate and the inquiries on the Rachel Maddow show on MSNBC.

Although she kicks off with the normal straw man about hiding declines in global temperature, she soon moves on to something that is closer to the truth, explaining that hide the decline was about hiding the failure of the proxies to track temperatures in the period after 1960. This is good, but she then elides into an important piece of misinformation, by suggesting that this is an issue that only affects the post-1960 period. This is of course, not the case. Since nobody knows what causes the divergence, nobody knows whether it affects earlier periods or not, although of course there are strong suggestions that it does.

Click to read more ...

Cue outrage

Dan Satterfield, a broadcast meteorologist in the USA, has written an article for the NCAR website, linking weather extremes to global warming.

The past twelve months have seen some of the most extreme weather of modern times, especially in North America. NOAA announced in January that in 2011 the United States suffered through a total of 14 weather disasters that cost over a billion dollars each. Among these were the Texas drought that was literally off the charts, and of course the deadly tornadoes in Alabama and Joplin, Missouri, among other places. More of the United States was either extremely wet or extremely dry in 2011 than in any other year on record.

Click to read more ...