In 2002, Lonnie Thompson drilled a 460 meter ice core in a col between Mounts Bona and Churchill in Alaska. As of October 2003, they had analyzed over 5600 samples and concluded that the core covered approximately 2500 years. A presentation was made at AGU in December 2004. The data was not discussed in IPCC AR4 or even in Thompson’s 2006 PNAS article. Actually, not only is the data completely unarchived, to date, there is no journal publication whatever of these results (funded by the National Science Foundations Office of Polar Programs grant OPP-0099311).
In mining promotions, whenever results are delayed, you can be 99% sure that they are not good results. Promoters can delay results a little bit hoping that more drilling will get a good hole, but there’s not much discretion. For some time, I’ve noticed the non-reporting of Bona Churchill (which I’ve compared to a similar situation at Sheep Mountain) and surmised that the results were not “good” for Thompson’s viewpoint: otherwise we’d have heard about it. Here’s one such prediction:
Heres my prediction about dO18 levels at Bona Churchill.: 20th century dO18 levels will be more negative (“colder”) than levels in the early 19th century – the opposite pattern to the pattern that Thompson is promoting for tropical glaciers.
While the results remain unpublished, Follow the Money noted a reference to Bona Churchill in a workshop proceeding here, which contained a PPT presentation (81 MB) by Lonnie Thompson, the abstract to which stated:
Records providing the necessary time perspective may be reconstructed from chemical and physical properties preserved in the regional ice cover and ocean sediments. Comparisons are made among the geographically dispersed, annually dated ice cores records from the Antarctic Peninsula, the tropical Quelccaya ice cap (Peru) and Bona-Churchill (southeast Alaska) over the past 500 years. Decadally averaged δ18O histories demonstrate that the current warming at high elevations in mid- to low-latitudes is unprecedented for at least the last two millennia.
The PPT presentation contained an interesting graphic providing the first information on Bona-Churchill levels. And in sufficient detail to test my prediction. How do you think that I did on my prediction?
Just for fun, let’s review the history of the Bona-Churchill project a little. Skip to the end if you want the results without waiting.
The purpose of the Bona-Churchill drilling (presumably drawn from the proposal to NSF) is set out on an Ohio State webpage here:
Ice core reconstruction of North Pacific climate variability and environmental history from the Bona-Churchill Ice Field, Alaska. This project is funded by the National Science Foundations Office of Polar Programs (OPP-0099311) and is in its third year.
This project was designed to retrieve and analyze ice cores from the col situated between Mt. Bona and Mt. Churchill (61o 24′ N, 141o 42′ W; 4420 m asl) in Wrangell-St Elias Mountains of southeastern Alaska. These records will fill a significant void in the high resolution climate history of this region. These new ice core records will complement and extend the existing tree ring-based climate records for the region and will add to the suite of high resolution ice core histories now emerging from other north polar ice fields. Global scale syntheses of past climate variability include ice core contributions from both Antarctica and Greenland as well as from ten lower latitude, high altitude sites in Tibet, South America and Africa. To date the unique paleohistories preserved in Alaskas ice fields have not been tapped and thus have not contributed to this global climate synthesis. The sparseness of high resolution climate histories from the northeastern side of the Pacific Basin has been a major obstacle to advancing our understanding of the rapid and recent changes in the dynamical state of the Pacific region and its global teleconnections. The ice cores attained from the Bona-Churchill col will help fill this void and provide critical new insight to the climate history in this region.
Our scientific objectives for the Bona-Churchill cores include:
(1) Assess whether the warming of the last 30 years that appears to be amplified at high elevations in the tropics and subtropics extends to northwestern North America;
(2) Assess the character of the most recent step change in the dynamics of the Pacific Basin climate regime that occurred in 1976-77 and explore whether similar abrupt transitions have occurred in the past and if so, determine when and of what magnitude were the changes;
(3) Explore whether the recently identified multi-decadal ENSO-like mid-latitude climate variability has its roots in the tropical Pacific;
(4) Determine the bottom age of the ice on Bona-Churchill col; and
(5) Determine whether Mt. Churchill is indeed the source of the White River Ash.
By October 2003, Thompson’s group reported that they had completed over 5600 samples from over 75% of the core, which was estimated to cover 2500 years:
The analyses of the Bona-Churchill ice cores are now underway in the laboratories at OSUs BPRC. The primary measurements that are being made continuously along the length of all cores include the concentration and size distribution of insoluble microparticles (dust), δ18O, δD, and concentrations of the major anion and cation species. The upper sections of the cores have been analyzed for total Beta radioactivity. The annual accumulation rate has averaged ~1100 mm of water equivalent over the recent past. As of October 2003 we have analyzed 5600 δ18O, δD, dust and chemistry samples representing 320 meters of the 460-meter deep ice core. The dust and calcium concentrations show distinct annual variations and the preliminary results suggest that the annually resolved record will cover more than 2500 years. This bodes well for the recovery of a very high-resolution record of past climatic and environmental variability from these cores.
In an interview in May 2004, Thompson noted high levels of potassium in snow layers from the 1960s, which he thought might have come from China (given that potassium is an important fertilizer, it’s interesting to think of it being airborne at higher altitudes in the context of high-altitude tree ring growth):
A second surprise in the Bona-Churchill ice core is the high level of potassium found in snow layers from the 1960s.
Potassium is not something you usually find in an ice core, Thompson said.
His guess is that the potassium is from China, where wind lifted it from fertilized dry fields and carried it across the Pacific to settle in Alaska and elsewhere in North America. Thompson said he doesnt know if the level of potassium is high enough to boost the growth of Alaska plants.
A third question raised by the Bona-Churchill ice core is why the ice from 1,500 feet down in the core fell as snow in 1,000 B.C., which suggests that no ice existed on the mountain before then. The current theory of Alaskas past is that glaciers have covered at least the mountainous parts of the state for at least 12,000 years, when the last Ice Age started to wane. Though Thompson said volcanic heat might have affected the Bona-Churchill ice core, it shows no evidence of this.
Is it possible that the ice totally disappeared, and these glaciers are a function of climate in the last 5,000 years, in the cooling period that started in the middle of the Holocene (the last 11,000 years of Earths history)? Thompson said. To me, its a very important story to unravel.
In December 2004, there were two presentations at the AGU Fall Meeting. In one presentation, they stated:
In 2003, six ice cores measuring 10.5, 11.5, 11.8, 12.4, 114 and 460 meters were recovered from the col between Mount Bona and Mount Churchill (61° 24′N; 141° 42′W; 4420 m asl). These cores have been analyzed for stable isotopic ratios, insoluble dust content and concentrations of major chemical species. Total Beta radioactivity was measured in the upper sections. The 460-meter core, extending to bedrock, captured the entire depositional record at this site where ice temperatures ranged from -24° C at 10 meters to -19.8° C at the ice/bedrock contact. The shallow cores allow assessment of surface processes under modern meteorological conditions while the deep core offers a ∼1500-year climate and environmental perspective. The average annual net balance is ∼~1000 mm of water equivalent and distinct annual signals in dust and calcium concentrations along with δ 18O allow annual resolution over most of the core. The excess sulfate record reflects many known large volcanic eruptions such as Katmai, Krakatau, Tambora, and Laki which allow validation of the time scale in the upper part of the core. The lower part of the core yields a history of earlier volcanic events. The 460-m Bona-Churchill ice core provides a detailed history of the `Little Ice Age’ and medieval warm periods for southeastern Alaska. The source of the White River Ash will be discussed in light of the evidence from this core. The 460-m core also provides a long-term history of the dust fall that originates in north-central China. The annual ice core-derived climate records from southeastern Alaska will facilitate an investigation of the likelihood that the high resolution 1500-year record from the tropical Quelccaya Ice Cap (Peru) preserves a history of the variability of both the PDO and the Aleutian Low.
In a second presentation, they reported:
The White River Ash (WRA) is a well-documented bi-lobate Plinian deposit covering as much as 540,000 square km of the Yukon Territory, Canada and adjoining eastern Alaska. Recent studies have identified the source of the ash as Mount Churchill in the St. Elias Mountains of southeastern Alaska by comparing pumice deposits from the summit area of Mount Churchill with more distal pumice deposits of the WRA (e.g. McGimsey et al., 1990; Richter et al., 1995). In spring 2002 a team from The Ohio State University’s (OSU) Byrd Polar Research Center recovered a 460-m long ice core drilled to bedrock in the col (elevation 4420 masl) between Mount Churchill and Mount Bona (4 km southwest) to reconstruct a proxy climate history for the region. This core is also ideal to assess whether Mount Churchill is the source of the WRA. No evidence of a visible ash layer was encountered during drilling. Borehole temperatures of -24 degrees C at 10m depth and -19.8 degrees C at the ice-bedrock interface indicate the glacier is frozen to its bed. After being returned frozen to OSU the core was cut into 12,162 samples that were analyzed for stable isotopic ratios, insoluble particles and soluble chemistry. A preliminary time scale was developed using annual variations in oxygen isotopes, dust and calcium concentrations, beta-radioactivity (bomb horizons) and well-documented historic volcanic eruptions. The ∼1500 year long record shows elevated sulfate values at ∼803AD possibly associated with the second of two eruptions in the past 2000 years that produced the eastern lobe of the WRA deposit. The paleoclimate records appear to be stratigraphically continuous and show no evidence of a depositional hiatus. The absence of an ash layer in the core suggests that the WRA deposit requires further investigation, and the source and age of the WRA will be addressed.
Fisher and Mount Logan
Around the same time as Thompson was drilling the Bona-Churchill ice field, David Fisher and associates were drilling a similar legnth of core at the Eclipse ice field near Mount Logan.
Two cores (345 and 130 m) were recovered in 2002 (Table I).
They submitted a manuscript on May 5, 2005, revised and accepted Jan 13, 2006, published in Sept 2006. Fisher et al showed an interesting graphic (previously discussed here) which showed a dramatic and sharp drop in the 1840s (as well as a sharp change ~800 AD held to signal the start of the MWP.
Original Caption: FIGURE 3. (A) The d18O for PRCol (5 340 m asl) and the dD for Eclipse (3 017 m asl) ice core sites, smoothed with a 5-years low pass filter. At PRCol there is an abrupt shift in d18O of about 3 ca. A.D. 1840, that is not evident in the Eclipse record. The older NWCol Logan core also has a similar shift at the same date.We suggest that prior to A.D. 1840 the moisture flow was predominantly zonal with North Pacific sources of water, and after A.D. 1840 the flow was mostly “modern” delivering moisture from more southerly sources. The higher site receives relatively much more distant southern warm-source moisture than the lower. Compare the A.D. 1840 shift to that of A.D. 1976. (B) The deuterium excess plot for PRCol, indicating a major shift of moisture source ca. A.D. 1840. The larger excess points to warmer source oceans providing the moisture. (C) A plot of ENSO strength statistics implying that a regime shift occurred in the mid-19th century.
Fisher et al hypothesized a re-arrangement of hemispherical wind circulation patterns in the 1840s, taking place over only a few years, changing the moisture source and thus dO18 values.
The synoptic situation that would go along with the shift is that a deeper more northwest-centred Aleutian Low would draw moisture from farther south.Comparison of stable isotope series over the last 2000 years and model simulations suggest sudden and persistent shifts between modern (mixed) and zonal flow regimes of water vapour transport to the Pacific Northwest. The last such shift was in A.D. 1840. Model simulations for modern and “pure” zonal flow suggest that these shifts are consistent regime changes between these flow types, with predominantly zonal flow prior to ca. A.D. 1840 and modern thereafter. The 5.4 and 0.8 km asl records show a shift at A.D. 1840 and another at A.D. 800. It is speculated that the A.D. 1840 regime shift coincided with the end of the Little Ice Age and the A.D. 800 shift with the beginning of the European Medieval Warm Period. The shifts are very abrupt, taking only a few years at most.
The dO18 history is a bit different from the Mount Logan history in that the 20th century decline is more mooted; squinting at the graphic, one can perhaps discern a small decline between the two centuries. However, the visual impression is that there has been negligible change between the 19th and 20th centuries in dO18 values and that there were “warmer” values from about 1350-1600. Does it mean anything? Who knows. If one thought that there had been strong warming in Alaska in the 20th century (and there is evidence of this), then one could hardly say that the dO18 histories were a useful proxy for this warming.
Thompson and Moseley-Thompson say of this data:
Decadally averaged δ18O histories demonstrate that the current warming at high elevations in mid- to low-latitudes is unprecedented for at least the last two millennia.
The U-word again. But is there any evidence of this from the Bona-Churchill δ18O history showing unprecedented warming? I can’t see any. Maybe you need to be a dendrochronologist to see it. Again, please note that the question here is not whether there is or isn’t “unprecedented” warming, but whether the Bona-Churchill δ18O history provides any evidence of unprecedented warming? I think not.
I think that my prediction for Bona-Churchill was pretty good: there’s nothing here that “helps” Thompson’s story that there are higher ice core dO18 values in the 20th century show global warming.
D.A. FISHER*, C.WAKE, K. KREUTZ, K.YALCIN, E. STEIG, P. MAYEWSKI, L. ANDERSON, J. ZHENG, S. RUPPER, C. ZDANOWICZ, M. DEMUTH, M. WASZKIEWICZ, D. DAHL-JENSEN, K. GOTO-AZUMA, J.B. BOURGEOIS, R.M. KOERNER, J. SEKERKA, E. OSTERBERG, M.B. ABBOTT, B.P. FINNEY and S.J. BURNS; STABLE ISOTOPE RECORDS FROM MOUNT LOGAN, ECLIPSE ICE CORES AND NEARBY JELLYBEAN LAKE.WATER CYCLE OF THE NORTH PACIFIC OVER 2000 YEARS AND OVER FIVE VERTICAL KILOMETRES: SUDDEN SHIFTS AND TROPICAL CONNECTIONS, Géographie physique et Quaternaire, 2004, vol. 58. url
Lonnie G. Thompson, Ellen Mosley-Thompson 2006. Glaciological evidence for abrupt climate change: past and present. NSIDC: An International Workshop: Antarctic Peninsula Climate Variability: Observations, Models, and Plans for IPY Research. ftp://sidads.colorado.edu/pub/ppp/IPY-APCV/LonnieThompsonWorkshop.pps