In 2000, Lonnie Thompson drilled ice cores at Kilimanjaro which were published 2 years later. In 2003, they drilled ice cores at Bona Churchill in Alaska. They made a presentation at AGU with press release in 2004 about looking for (and not finding) White River Ash from an 803 AD eruption.
But no publications so far.
Here’e 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.
There is evidence for this prediction over and above conclusions drawn simply from the lack of published results.
The evidence comes from a recent paper by Fisher and 22 other authors discussing ice core and proxy evidence from nearby. Here is the key graphic summarizing dO18 values for Eclipse ice core showing 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 hypothesize 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.
So extrapolating from the nearby dO18 results, I project that 20th century dO18 at Bona Churchill will be relatively negative. Of course, it is highly likely that there are not just excellent, but really excellent reasons why results from Bona Churchill (probably showing lower dO18 values) have not been archived or even published.
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