Mann rose to prominence by supposedly being able to detect “faint” signals using “advanced” statistical methods. Lewandowsky has taken this to a new level: using lew-statistics, lew-scientists can deduce properties of population with no members. Josh summarizes the zen of lew-statistics as follows:
Another bogus claim from Lewandowsky would hardly seem to warrant a blog post, let alone a bogus claim about people holding contradictory beliefs. The ability of many climate scientists to hold contradictory beliefs at the same time has long been a topic of interest at climate blogs (Briffa’s self contradiction being a particular source of wonder at this blog). Thus no reader of this blog would preclude the possibility that undergraduate psychology students might also express contradictory beliefs in a survey.
Nonetheless, I’ve been mildly interested in Lewandowsky’s claims about people subscribing to contradictory beliefs at the same time, as for example, the following:
While consistency is a hallmark of science, conspiracy theorists often subscribe to contradictory beliefs at the same time – for example, that MI6 killed Princess Diana, and that she also faked her own death.
Lewandowsky’s assertions about Diana are based by an article by Wood et al. entitled “Dead and Alive: Beliefs in Contradictory Conspiracy Theories”. A few months ago, I requested the supporting data from Wood. Wood initially promised to provide the data, then said that he had to check with coauthors. I sent several reminders without success and eventually without eliciting any response. I accordingly sent an FOI request to his university, accompanied by a complaint under any applicable university data policies. The university responded cordially and Wood immediately provided the data.
The most cursory examination of the data contradicted Lewandowsky’s claim. One can only presume that Lewandowsky did not carry out any due diligence of his own before making the above assertion.
A trivia question today for CA readers.
Continue reading →
The article itself presents a Holocene temperature reconstruction that is very much at odds both with Marcott et al 2013 and Mann et al 2008. And, only a few weeks after IPCC expressed great confidence in the non-worldwideness of the Medieval Warm Period, Rosenthal et al 2013 argued that the Little Ice Age, Medieval Warm Period and Holocene Optimum were all global events.
Although (or perhaps because) the article apparently contradicts heroes of the revolution, Rosenthal et al 2013 included a single sentence of genuflection to CAGW:
The modern rate of Pacific OHC change is, however, the highest in the past 10,000 years (Fig. 4 and table S3).
In the Columbia and Rutgers press releases accompanying the article, this claim was ratcheted up into the much more grandiose assertion that modern warming is “15 times faster” than in previous warming cycles over the past 10,000 years (though the term “15 times faster” is not actually made in the peer reviewed article):
In a reconstruction of Pacific Ocean temperatures in the last 10,000 years, researchers have found that its middle depths have warmed 15 times faster in the last 60 years than they did during apparent natural warming cycles in the previous 10,000.
Rather than quoting the article itself, Michael Mann, an academic activist at Penn State University, repeated the claim from the press release in an article at Huffington Post entitled “Pacific Ocean Warming at Fastest Rate in 10,000 Years”.
However, both the claim in the press release and the somewhat weaker claim in the article appear to be unsupported by the actual data. Continue reading →
A question for readers: which of the following proxies are used to reconstruct past Southern Hemisphere temperature in the IPCC’s graphic (Figure 5.7b) showing SH reconstructions:
1. Graybill’s California strip-bark bristlecone chronologies
2. upside down and contaminated Finnish lake sediments
3. European instrumental temperature data
4. Antarctic ice core d18O isotope data covering the medieval period
Gifford Miller’s most recent study on radiocarbon dates of Baffin Island moss has attracted recent publicity, including covers at Judy Curry, WUWT and Jim Bouldin, due to its claim to have demonstrated that the present is the warmest in 44000 years.
Over the past decade, Miller has been taking radiocarbon dates on moss exposed from receding glaciers/ice caps on Baffin Island. Up to his most recent study, these dates have been used to develop a chronology of ice expansion and recession. Miller’s sampling protocol focuses on “ice caps” rather (moving) glaciers and on short-lived moss (rather than longer-lived macrofossils). Miller assumes (reasonably enough) that the moss was engulfed by ice cap expansion – the expansion indicating a decline in temperature – and that the moss has not been subsequently exposed (since it degrades relatively rapidly upon exposure).
Miller’s article reports on 145 radiocarbon dates from recently-exposed moss, the vast majority of which are dated to the past two millennia, as shown in the histogram below of radiocarbon ages for the 135 Holocene dates (plus 10 pre-Holocene dates.)
At the majority of locations, receding ice is exposing moss that was engulfed by Little Ice Age glacier expansion. At a sizable minority of locations, receding ice is exposing moss that was engulfed by earlier glacier expansions (especially first millennium AD and first millennium BC). These Holocene glacier expansions are consistent with other millennial evidence e.g. treelines moving south, ice core melt and oxygen isotopes. In an unpublicized part of Miller et al 2013, Miller estimated a secular lowering of glacier of 129 m/ 1000 years, with a 19th century low about 200 m below 20th century levels.
From the lowering of glacier lines, Miller estimated a reduction of about 2.7 deg C in summer temperature over the past 6000 years or so. Miller observed that estimates from CMIP5 climate models were much lower – about 1.1 deg C – from which he deduced that things were worse than we thought.
Some of the exposed samples are increasingly earlier in the Holocene, with the earliest Holocene sample at 4285 radiocarbon BP (calibrated 4900 BP). It should be noted that these dates do not coincide with peak Holocene warmth, dated to ~6000-7000 BP on much other evidence.
In addition to the 135 sites where Late and Holocene mosses have been exposed, Miller sampled 4 sites (10 samples) where the mosses were dated deep into the LGM or at or near the radiocarbon detection limit (~44000 years). It was on the basis of these samples that the warmest in 44000 years claim arose.
Curiously, this claim is remarkably similar to claims made by Lonnie Thompson in 2005 at Quelccaya (see CA discussion here, here here). In this case, “remarkably similar” means remarkably similar as normally understood, rather than as used in climate science. Thompson also based his claim on radiocarbon dates from moss (Distichia) exposed by receding glaciers. As in Baffin Island, the vast majority of Quelccaya radiocarbon dates were from the 4200BP and later, but there was at least one at the radiocarbon detection limit. Like Miller, Thompson hypothesized that this moss was evidence that temperatures were the warmest since the Eemian.
Since Thompson’s 2005 news release, there have been a couple of academic articles on the Quelccaya moss with Holocene dates, e.g. here which reported:
In this case, we can infer that not only one species but a community of plants occurred at a high-elevation location ∼5000 yr ago under likely warmer conditions.
However, I haven’t seen anything further about Thompson’s “Eemian” moss. If anyone knows anything more, I’d be interested. The outcome of Thompson’s “Eemian” moss seems like it would be relevant to the appraisal of Miller’s Eemian moss.
Miller et al provided the following helpful photo of the location from which one of the “Eemian” samples was taken. Miller commented that the moss is observed only in the immediate receding vicinity: the rock quickly becomes barren.
Figure 2. Photo of site of samples M10-B231v and B232v, dated at or near detection limit.
There are a couple of nearby locations at which the exposed moss from receding ice caps at slightly greater altitudes merely has Holocene dates. “Eemian” sample B231v is at 1395m altitude. However, samples B223v and B226v are both slightly higher and located nearby (with a km or two) along the same ridge, but the exposed moss is merely Holocene (~4200 BP). A question: How does one reconcile the supposed in situ continuity of the little “ice cap” in the vicinity of sample M10-B231v (1395 m) since 44000 BP with recession in the vicinity of nearby higher M10-B226v (1438 m)?
Postscript: I’ve covered Miller’s work (relatively favorably) in the past – see here and here. Miller is a reputable scientist whose work rises above the data snooping, data mining and regression against increasing trends of self-opinionated verbiage (to borrow Briffa’s phrase) that is too prevalent in the field.
Much of Miller’s work has been the articulation of Late Holocene glaciation, up to and including its relative maximum in the Little Ice Age, from which numerous Baffin Island locations are still emerging in his recent study. Miller was coauthor of the Hvitavatn (Iceland) sediment series, with Miller attributing the Little Ice Age maximum of this proxy to cold, rather than warmth, and conversely for the Medieval period. As I noted in my coverage of PAGES2K, Kaufman and the PAGES2K authors used Miller’s series upside down, thereby attributing its 19th century maximum to warmth rather than cold. The PAGES2K Arctic reconstruction does not stand or fall on this error. However, it is one of relatively few series that show any Stick-ness and the other Stick contributors also have serious problems (e.g. contaminated sediments.)
Update: Oct 27. Andrews et al 1972 has an air photo on which the locations of B221v and B223v are shown. First, here is a google earth image looking east towards Broughton Island with sites marked – oriented to correspond to the 1972 air photo. The red pin shows the location of the ancient moss.
After discussing recent deterioration in summer temperatures, Andrews et al 1972 observed:
The evidence strongly suggests that glaciation of Baffin Island will herald the next glaciation of North America although the timing of such development is unknown. The climatic glacial mode may develop rapidly, but there is a lag of the order of 10,000 years in the subsequent buildup of a continental ice sheet… The recent climatic fluctuations in the area are on too short a timescale to be viewed with alarm. The main control on glacierization in eastern Baffin Island is snowfall, not temperature.
Co-authors of Andrews et al 1972 included Gifford Miller and Raymond Bradley.
AR5 Second Order Draft (SOD) Figures 1.4 and 1.5 showed the discrepancy between observations and projections from previous assessment reports. SOD Figure 1.5 (see below as annotated) directly showed the discrepancy for AR4 without additional clutter from earlier assessment reports. Even though AR4 was the most recent and most relevant assessment report, SOD Figure 1.5 was simply deleted from the report.
Nor can it be contended that IPCC erroneously located the projections in SOD Figure 1.5, as SKS claimed here in respect to SOD Figure 1.4. The uncertainty envelope shown in SOD Figure 1.5 was cited to AR4 Figure 10.26. As a cross-check, I digitized relevant uncertainty envelopes from AR Figure 10.26 (which I’ll show later in this post) and plotted them in the figure below (A1B – red + signs; A1T orange). They match almost exactly. Richard Betts acknowledged the match here.
AR5 Figure 1.4
Having deleted the informative (perhaps too informative) SOD Figure 1.5, IPCC’s only comparison between AR4 projections and actuals is in the revised Figure 1.4, a figure that seems more designed to obscure than illuminate.
In the annotated version shown below, I’ve plotted the AR4 Figure 10.26 A1B uncertainty range in yellow. Unfortunately, Figure 1.4 no longer shows an uncertainty envelope for AR4 projections. Here one has to watch the pea carefully. Uncertainty envelopes are shown for the three early assessments, but not for AR4, though it is the most recent. All that is shown for AR4 are 2035 uncertainty ranges for three AR4 scenarios (including A1B) in the right margin, plus a spaghetti of individual runs (a spaghetti that does not correspond to any actual AR4 graphic.) From the right margin A1B uncertainty range, the missing A1B uncertainty range can be more or less interpolated, as I have done here with the red envelope. I matched 2035 uncertainty to the right margin and interpolated back to 2000 based on the shape of the other envelopes. The re-stated envelope is about twice as wide as the actual AR4 Figure 10.26 uncertainty envelope that had been used in SOD Figure 1.5. Even with this much expanded envelope, HadCRUT4 observations are at the very edge of the expanded envelope – and well outside the actual AR4 Figure 10.26 envelope.
Figure 2. AR5 Figure 1.4 with annotations. The yellow wedge shows the uncertainty range from AR4 Figure 10.26 (A1B). The red wedge interpolates the implied uncertainty range based on the right margin A1B uncertainty range.
AR4 Figure 10.26
Richard Betts recognized that there was no location error in connection with AR4 projections, but argued (see here) that the comparison in AR5 Figure 1.4 was “scientifically better” than the comparison in the SOD figure which, as Betts acknowledged, was “based on” an actual AR4 graphic (AR4 Figure 10.26).
However, if one is comparing AR4 projections to observations, IPCC is obliged to compare to actual AR4 graphics. Figure 10.26 was properly recognized in the SOD as the relevant comparison. It was also cited in contemporary (early 2008) discussion of AR4 projections by Pielke Jr (e.g here) and Lucia (here here)
AR4 Figure 10.26 was a panel diagram, the bottom row of which (see below) showed projections for GLB temperatures under six emissions scenarios, including A1B, with the editorial AR4 comment that the models “compare favourably” with observations.
Figure 3. Bottom row of AR4 Figure 10.26 showing uncertainty ranges for GLB temperature for six SRES scenarios. Original caption (edits show information for bottom row): Fossil CO2, CH4 and SO2 emissions for six illustrative SRES non-mitigation emission scenarios … and global mean temperature projections based on an SCM tuned to 19 AOGCMs. The dark shaded areas in the bottom temperature panel represent the mean ±1 standard deviation for the 19 model tunings. The lighter shaded areas depict the change in this uncertainty range, if carbon cycle feedbacks are assumed to be lower or higher than in the medium setting… Global mean temperature results from the SCM for anthropogenic and natural forcing compare favourably with 20th-century observations (black line) as shown in the lower left panel (Folland et al., 2001; Jones et al., 2001; Jones and Moberg, 2003).
The next graphic shows the effect of AR5’s “re-stated” uncertainty range on Figure 10.26. The right margin uncertainty ranges of Figure 1.4 have been inset at the correct location, with the ends of the uncertainty range corresponding to 2035 values of the red envelope showing the re-stated uncertainty range. Despite the doubling of uncertainty in the AR5 restatement, recent HadCRUT4 values are at the very edge of the expanded envelope.
Figure 4. Detail of AR4 Figure 10.26 with annotation. HadCRUT4 is overplotted: yellow to 2005, orange thereafter. Original reference period is 1981-2000; the 1961-90 reference period used in AR5 is shown on the right axis.
In the final draft document sent to external reviewers, SOD Figure 1.5 directly compared projections from AR4 Figure 10.26 to observations, a comparison which showed that recent observations were running below the uncertainty envelope. The reference period for the AR4 uncertainty envelope was well-specified (1981-2000) and IPCC correctly transposed the envelope to the 1961-1990 reference period used in SOD Figure 1.5.
IPCC defenders have purported to justify changes to the location of uncertainty envelopes from the three early assessment reports on the basis that IPCC had erroneously located them in SOD Figure 1.4. Thousands of institutions around the world routinely compare projections to actuals without making mistakes about what their past projections were. Such comparisons are simple accounting, rather than cutting-edge science. It is disquieting that such errors persisted into the third iteration of the documents and the final version sent to external reviewers.
But, be that as it may, there was no reference period error concerning AR4 projections or in SOD Figure 1.5. So reference period error is not a reason for the deletion of this figure.
Richard Betts did not dispute the accuracy of the comparison in SOD Figure 1.5, but argued that the new Figure 1.4 was “scientifically better”. But how can the comparison be “scientifically better” when uncertainty envelopes are shown for the three early assessment reports, but not for AR4. Nor can a comparison between observations and AR4 projections be made “scientifically better” – let alone valid in accounting terms – by replacing actual AR4 documents and graphics with a spaghetti graph that did not appear in AR4.
Nor is the new graphic based on any article in peer reviewed literature.
Nor did any external reviewers of the SOD suggest removal of Figure 1.5, though some (e.g. Ross McKitrick) pointed out the inconsistency between the soothing text and the discrepancy shown in the figures.
Nor, in the absence of error, is there any justification for such wholesale changes and deletions after the third and final iteration had been sent to external reviewers.
In the past, IPCC authors famously deleted data to “hide the decline” in Briffa’s temperature reconstruction in order to avoid “giving fodder to skeptics”. Without this past history, IPCC might be entitled to a little more latitude. However, neither IPCC nor its supporting institutions renounced such conduct or undertook avoid similar incidents in the future. Thus, IPCC is vulnerable to concerns that its deletion of SOD Figure 1.5 was primarily motivated to avoid “giving fodder to skeptics”.
Perhaps there’s a valid reason, but it hasn’t been presented yet.
Figure 1.4 of the Second Order Draft clearly showed the discrepancy between models and observations, though IPCC’s covering text reported otherwise. I discussed this in a post leading up to the IPCC Report, citing Ross McKitrick’s article in National Post and Reiner Grundmann’s post at Klimazweiberl. Needless to say, this diagram did not survive. Instead, IPCC replaced the damning (but accurate) diagram with a new diagram in which the inconsistency has been disappeared.
A few days ago, Jochem Marotzke, an IPCC Coordinating Lead Author and, according to Der Spiegel, “president of the German Climate Consortium and Germany’s top scientific representative in Stockholm”, was praised (e.g. Judy Curry here) for his promise that the IPCC would address the global warming hiatus “head on” despite pressures from green factions in government ministries and for his declaration that “climate researchers have an obligation not to environmental policy but to the truth”.
However, it turned out that Marotzke’s promise was merely another trick. Worse, it turns out that Marotzke already knew that the report would not properly deal with the hiatus – which, in a revealing interview, Marotzke blamed on an ” oversight” (h/t to Judy Curry here). Worse, it turns out that IPCC authors were themselves complicit during the plenary session in causing information about the discrepancy between models and observations to be withheld from the SPM, as shown by thus far undiscussed minutes of the IPCC plenary session. Continue reading →