Met Office Hindcast

In a recent post, I noted the discrepancy between the UK Met OFfice contribution to IPCC AR5 and observations (as many others have observed), a discrepancy that is also evident in the “initialized” decadal forecast using the most recent model (HadGEM3). I thought that it would be interesting to examine the HadGEM2 hindcast to see if there are other periods in which there might have been similar discrepancies. (Reader Kenneth Fritsch has mentioned that he’s been doing similar exercises.)

In the figure below, I’ve compared HadCRUT4 (anomaly basis 1961-1990) to the Met Office CMIP5 contribution (red), converted to 1961-90 anomaly.

Continue reading


More Met Office Hypocrisy

In yesterday’s post, I observed that Nature’s recent news article on Met Office decadal forecasts failed to show the most recent Met Office decadal forecast and that its inclusion would not have permitted the Nature headline. I also showed the large change from the Met Office submission to IPCC AR5 and their current decadal forecast. Asked to comment by Anthony Watts, Richard Betts of the Met Office did not explain why the Met Office either signed off on or had not objected to the omission of their most recent forecast. Instead, Betts claimed that my plot was “wrong” because “HadGEM2 not an initialised forecast, so Steve is wrong to plot it from 2010 high point – exaggerates difference”… as though this were responsive:

BETTS TWEET

However, I had directly plotted from data from the Met Office so there was no inaccuracy in my graphic despite Betts’ implication. Nor, needless to say, there is no scientific or statistical principle forbidding the illustration of initialized and uninitialized forecasts on the same graphic. Ironically, as shown below, the UK Met Office had themselves done so in the very article (Smith et al 2012 Clim Dyn) from which the Nature News article had been derived.

Continue reading

Nature-mag Hides the Decline

Earlier this year, David Whitehouse of GWPF drew attention to a striking decrease in the UK Met Office decadal temperature forecast, that had been quietly changed by the Met Office on Christmas Eve. Whitehouse’s article led to some contemporary interest in Met Office decadal forecasts. The Met Office responded (see here); Whitehouse was also challenged by Greenpeace columnist Bob Ward.

Fast forward to July 10, 2013. Using UK Met Office decadal forecasts, Jeff Tollefson of Nature reported as a “News Feature” that “The forecast for 2018 is cloudy with record heat”, covered by Judy Curry here.

An innocent reader would presume that a Nature “News Feature” reporting on Met Office decadal forecasts would include the current Met Office decadal forecast. However, this proves not to be the case. Tollefson showed an older decadal forecast issued prior to the downward revision of the Met Office decadal forecast to which Whitehouse had drawn attention. Tollefson showed the multi-model mean from Smith et al 2012 (Clim Dyn), which has negligible difference from the 2011 Met Office decadal forecast. Had Tollefson shown the “decline” in the current decadal forecast, Nature would not have been able to make the same unequivocal headline. Continue reading

Paul Nurse and his Extra-Special Big Boy Pants

As a change from my Briffa reconsideration, I was intrigued by the recent correspondence between Nigel Lawson and Paul Nurse, President of the Royal Society, discussed from time to time at Bishop Hill, most recently here. Continue reading

Evasions and Fantasy at Real Climate

Several readers have asked me to respond to recent comments about me at Real Climate: briefly, Osborn has made one misrepresentation after another and made statements with seemingly complete indifference as to whether he has any basis for making the claims.

In respect to Schmidt’s whinge, as Lucia sagely observed a couple of years ago in connection with Schmidt’s defence of upside-down Tiljander, one cannot assume that people actually asked the questions that Schmidt says they asked or that his answers are adequate because he says so:

I might suggest that you are assuming that people asked the questions Gavin says they asked, and that Gavin’s answer to their questions is adequate because Gavin tells us his answer is adequate.

Schmidt and Osborn’s most recent comments were on July 2, the last day that comments were open on the thread, otherwise I would have attempted to respond at Real Climate. Unfortunately it takes more time to respond to their fantasies than it does for them to make them.
Continue reading

Treeline Changes and Altitude Inhomogeneity

The apparent inconsistency of ring width chronologies with analysis of changes in treeline elevation has long been an issue that I’ve urged specialists to address. Unfortunately Briffa et al 2013 failed to address the inconsistency at Polar Urals, even though they took note of an obsolete Shiyatov article on treeline changes. (More recent work by Shiyatov’s group has reported that medieval treelines at Polar Urals were even higher than previously thought.)

Worse, there have been significant changes in treeline at Polar Urals over the past 1500 years, an inhomogeneity that needs to be considered in RCS standardization. With the indecisiveness that is so characteristic of Briffa’s work, Briffa et al 2013 noted the possibility of altitude inhomogeneity, but then failed to investigate the problem or demonstrate that they could ignore the inhomogeneity. Continue reading

CRU Abandons Yamal Superstick

Unreported by CRU is that they’ve resiled from the Yamal superstick of Briffa 2000 and Briffa et al 2008 and now advocate a Yamal chronology, the modern portion of which is remarkably similar to the calculations in my posts of September 2009 here and May 2012 here, both of which were reviled by Real Climate at the time.

In today’s post, I’ll demonstrate the degree to which the new Briffa version has departed from the superstick of Briffa 2000 and Briffa et al 2008 and the surprising degree to which it approaches versions shown at CA.
Continue reading

Shiyatov and the Polar Urals

Nearly all readers agreed with the proposal (of my most recent post) for a comprehensive mapping and crossdating of all dead and living trees within one or more altitudinal transects in the Polar Urals, with the objective of achieving a crossdated dataset of at least 1000 subfossil trees and 500 living trees, each with accurately recorded coordinates and altitude. As opposed to the puny dataset used in the CRU chronology, which has less than 10% of this population and which, as archived, lacks accurate location and altitude information.

Several readers speculated that the costs of such a dataset would not be all that large and ought to be within the reach of the enormous climate science budgets. Rob Wilson wrote in – from the perspective of a practising (and, in contrast to CRU, actively collecting) dendro – saying that neither should the costs of such a program be under-estimated nor the difficulty in getting funding, concluding that such difficulties were the major factor in the shortage of long high-latitude chronologies:

As a quick response to Steve’s idealised approach. Yup – all well and good and I agree with it all. The reality is that for such replication requires multiple fieldtrips, several years (decades for Scandinavian work for example) and funding (plus bods on the ground). The reality is not so easy and funding is far from easy to acquire if you are considering, fieldwork, analytical costs (RW, MXD, isotopes etc), salaries etc. That is why there are so few millennial long chronologies from the high latitudes. The material is waiting there to be collected.

In a comment to the post, I observed that there was a punch line to it, a clue which a few readers understood but many didn’t.

The punch line is this: according to articles in peer-reviewed academic literature, the proposed comprehensive survey has already been done. (Indeed, the description of the recommended program was taken almost literally from an article by Stepan Shiyatov, who deserves great credit for carrying out a scientifically rational program for over 50 years under what must have been difficult circumstances.

In today’s post, I’ll summarize the extent of the Shiyatov dataset. (As a caveat, today’s post relies on information in peer reviewed academic literature; I have not personally had access to a digital version of Shiytov’s data.)
Continue reading

An RC Question about Briffa et al 2013

A commenter at Real Climate asked the following interesting question about the Urals/Yamal area reported in Briffa et al 2013:

So, for this region, what data do you wish you had, that could be plausibly gotten (i.e, not like 1000-year-old measured temperature records), that you don’t have? And why?

Jim Bouldin of RC described the question as an “excellent” one and on this point, RC and I are in agreement. It’s one that I have some ideas on.

On the surface, the Polar Urals are an almost ideal location for temperature-sensitive dendro. They are high latitude and high altitude. Within a distance of a kilometer or so, one can go from closed forest to alpine tundra. Subfossil trees are plentiful. Despite this plenty, Briffa et al 2013 use a very small dataset of subfossil trees, the limited coverage being exacerbated by their exclusion of 21 of 73 trees as being “root collars”. Due to their very small sample, CRU ends up with only two trees in part of the 11th century – a critical period in the modern-medieval comparison. There is an obvious need for more data.

In addition, there is an urgent need for accurate metadata, especially on the altitude of indovidual samples. Altitude is an important factor in local tree growth (as one can see by the sharp altitudinal gradient to the treeline), but the CRU metadata does not include the altitude of individual trees. Briffa et al 2013 does not even provide accurate information on the location of the sites used in its Polar Urals chronology. Altitude changes of samples are an important potential inhomogeneity that can only be addressed through accurate metadata, an issue apparently neglected in Briffa et al 2013 which splices living tree data from sites whose altitude appears to be materially lower than the reported altitude of the subfossil samples.

One relatively easy way of improving the situation would be to do extremely detailed map and measurements along the lines of what a geologist would do at a geological outcrop. The program described below may seem very detailed by dendro standards, but I’m convinced that it could be done at a reasonable cost and would result in an exemplary dendro data set.

The first step would be to mark out an altitudinal transect going from the alpine tundra to the closed forest. From Google Earth, it looks to me like this would be less than a km (say 800 m) A transect of width of 20 meters would be a workable width, giving a transect area of about 1.6 hectares, a practical area for detailed mapping. Geologists would mark the boundaries of the transect, perhaps with small cairns of stones at key points.

The next step would be to do a high-resolution map (say 1 cm map to 1 meter) on which the location of EVERY dead and living tree in the transect would be recorded. Information on each tree (height, etc…) should be recorded. Even if there are 5000 living trees and 1200 dead trees, this is a practical number. Geologists do this wort of detailed mapping all the time.

Next, the mappers could cut a cross-section from every dead tree and (say) 15% of the living trees, measure ring widths of the cores back at their lab and crossdate the cores using standard dendro techniques. Some proportion of the cores would not be crossdatable (especially those with relatively few rings), but suppose that 80% were crossdatable.

One would then end up with a data base of more than 800 crossdated subfossil cores and more than 500 crossdated living trees, each with exact coordinates and altitude. From our experience at Almagre, we know that a single dendro can collect tens of cores per working day and that the measurement of ring widths is automated and can be done relatively inexpensively. If “root collars” are the form in which subfossil data is available for older stunmps (e.g. medieval), then it would be prudent to sample living trees and standing dead trees at root collar as well as chest level, to facilitate analysis, rather than simply rejecting root collar data. While bending over may be a slight imposition on field dendros, geologists regularly bend over to examine rocks and I’m sure that dendros could be found to take cores at root collar as well as chest level. If not, I’d suggest that some field geologists be trained to do root collar cores.

I realize that this is an optimistic proposal. CRU dendros prefer to stay in East Anglia. Indeed, to my knowledge, no CRU dendro has ever even been to Yamal or Polar Urals. But there are capable Russian dendros who might be encouraged to take on this sort of program. From this sort of database, one could do real analysis, without having to listen to tiresome CRU whinging about poor replication. If one were lucky, one might even be able to accurately measure changes in treeline through the medieval period and Little Ice Age and modern warming, thereby obtaining a proxy that would be convincing to all parties to the debate. If the transect were properly marked, dendros could return to it in the future and definitively measure changes.

Optimistic or not, the collection of a dataset of over 1000-1500 crossdated cores from one (or two) well-located altitudinal transects at Polar Urals is one answer to the RC question.

Briffa Condemns Mann Reconstructions

Not in so many words, of course. However, Briffa et al 2013 took a position on the use of radially deformed tree ring cores that would prohibit the use of strip bark bristlecones in temperature reconstructions, thereby emasculating Mann’s reconstructions. And not just the Mann reconstructions, but the majority of the IPCC reconstructions used by Briffa in AR4.

I’ll report on this issue in today’s post. I’ve been looking closely at Briffa et al 2013 over the past 10 days and unsurprisingly there is issue after issue. According to CRU, they’ve been working on this article for over seven years and, needless to say, it is impossible to fully observe the pea in only a few days, especially when the adjustments have become so baroque that the chronology style is most aptly described as East Anglia Rococo, making the weary reader long for the classic simplicity of earlier CRU illusions like the Briffa Bodge and Hide the Decline. But more on this on another occasion. Continue reading

Follow

Get every new post delivered to your Inbox.

Join 2,902 other followers