Puruogangri (2000)

I was collating information on Thompson’s archiving of ice core information and noticed something interesting on the Puruogangri glacier in the Himalayas drilled in 2000 and still unarchived. (Thompson is one of the 20 wise men who recently weighed in with the Barton Committee on behalf of MBH.) In addition to not being archived, I haven’t identified any publication of this drill program. If anyone has seen one, I’d be interested and will amend this to incorporate this information. Thompson has made presentations about Puruogangri at several conferences. In 2002, Thompson told the AGU convention that the Puruogangri glacier (also the Dasuopu glacier in the Himalayas) were formed during the early Holocene warm period and their "formation/starvation" is "in response to precession-driven changes in solar radiation". Here is his abstract:

Ice core records from South America, Africa, the Himalayas and the Tibetan Plateau provide records of past changes in the hydrological cycle over a wide range of latitudes. Ice cores from seven high elevation (>5300 m asl) sites raise questions about the synchroneity of glaciation and the relative importance of temperature and precipitation in governing the growth of permanent ice fields in low latitude mountain ranges. Cores from Huascaràƒ⠮ (Peru at 9°S) and Sajama (Bolivia at 18°S) contain continuous records back ~ 19 ka and 25 ka, respectively and thus extend into Late Glacial Stage (LGS). Both glaciers undoubtedly survived the early Holocene warm period (10 to 6 ka B.P.), but neither contains a record of the entire LGS back to the previous interglacial. Thus, both mountains, among the highest in South America, appear to have been ice-free during a time when the Earth was in the grip of a ‘global’ glaciation. Conversely, the ice core records from the Dasuopu (28°N) and Puruogangri (34°N) glaciers suggest that ice existing today in the Himalayas and central Tibet formed during the early Holocene warm period. Glacier formation/starvation in the tropics and subtropics appears to be controlled by wetter/drier conditions in response to precession-driven changes in solar radiation. These ice core records are combined with more than 120 other paleoclimate to produce a global map of effective moisture changes between the Last Glacial Maximum and the Early Holocene. Changes in the tropical hydrological system over the last 25 ka have been extreme with the global pattern of climate in the Early Holocene being nearly opposite that during the Last Glacial Maximum. For example, the zonal belts in the deep tropics that experienced greater aridity during the LGS attained maximum humidity in the Early Holocene while at the same time the humid subtropical and mid-latitude belts became drier. The symmetry of these changes in moisture about the equator suggests a strong role for the Hadley circulation, and that either its position or its intensity or both were altered as the Earth moved from glacial to interglacial conditions.

Thompson’s 2004 Abstract to the AGU convention re-states the matter a little differently, but not much:

Three ice cores (215 m, 154 m, and 118 m in length) have been recovered [in 2000] from the Puruogangri Ice Field ( ‘ˆ⺳3\deg44′ – 34\deg03′N; \sim89° 00′ – 89° 20′E; 422.6 km2; 5970 masl) on the western end of the Tanggula Mountain Range. The ice bedrock temperature is -6.2° C. These cores have been continuously analyzed for stable oxygen isotopic ratios, concentrations of major ions and insoluble dust, and total Beta radioactivity. Annual layer thicknesses for the last 41 years reveal an average net annual accumulation 370 mm of water equivalent. The isotopic records from this very remote site indicate that the most significant isotopic enrichment (interpreted as atmospheric warming) in the ice field’s history has occurred in the last 50 years. Puruogangri is surrounded by sand dunes that lap onto its margins and as the sand moves in the spring, it produces a distinct annual dust layer that allows precise dating of the cores. Moreover, Puruogangri’s vertical relief facilitates the transportation of fragments of the sparse vegetation in the area to the top of the ice field. AMS 14C dating of several plant fragments from near the bottom of the core indicates that the Puruogangri Ice Field formed in the mid-Holocene. The possible reasons will be discussed as to why this high, cold and remote ice field is so young (mid-Holocene)

It’s odd that Thompson didn’t mention Kilimanjaro in this context, as my recollection is that this also formed in the Holocene and would be subject to precession effects. The Kilimanjaro glacier may be dated a little differently, but I wonder how solid the Kilimanjaro dating is in detail. If the formation/starvation of these tropical glaciers is precession driven, the passage of 8000-10000 years from their formation is a significant proportion of the precession cycle (which is about 22,000 years long). Wouldn’t one expect some serious effect simply from the precession cycle: maybe this was simply delayed by weak solar activity in the Little Ice Age? The Puruogangri program was financed by NSF grant ATM-0117113 managed for NSF by the ever-present David Verardo. The expiry date for the grant is July 31, 2005. As of today, Thompson has not archived any data from Puruogangri at WDCP. I would be very surprised if he archived data before the supposed expiry of his grant. For example, up to 2004, Lonnie Thompson had not archived any information from three Himalayan glaciers (Dunde, Guliya and Dasuopu) drilled in 1989, 1992 and 1995. The first archiving of informatio from these glacies occurred in 2004, after I had objected to Climatic Change (where he had re-published a graph showing information from these glaciers, Thompson grudgingly archived the decadal dO18 average used in the chart, but refused to archive the sample information or the chemistry. The raw data for ice cores is typically several thousand samples for each ice core with multiple measurements for each sample, including dO18, chemistry, dust etc. A complete data archive would obviously require that all samples be archived. I’ll get to a review of Thompson’s archiving quite soon, together with some interesting correspondence with Science, where Thompson published his results, in which I attempted to get Science to get Thompson to archive his data.

3 Comments

  1. John Cross
    Posted Jul 30, 2005 at 7:17 PM | Permalink | Reply

    It’s odd that Thompson didn’t mention Kilimanjaro in this context, as my recollection is that this also formed in the Holocene and would be subject to precession effects.

    I don’t think it would. Kilimanjaro is too close to the equator so precession effects won’t be significant.

    Steve: Could be. I thought that the precipitation in this region was monsoon-related, I’m pretty sure that the headwaters of the Nile are mostly fed by monsoon-related phenomena. If it was monsoon-related, wouldn’t it be affected by precession even if it was close to the equator if the monsoon was non-symmetric? I don’t know – just asking.
    It sure seems interesting that Puruogangri should have formed in the warm Holocene Optimum. Quelccaya puzzles me as well: the core is dated only to ~400 AD or so. Does that mean that it formed in hte 1st millennium?

  2. Louis Hissink
    Posted Jul 31, 2005 at 5:37 AM | Permalink | Reply

    The earth was in grip of …….?

    If I took a survey of the Antarctic glaciers today, I would not extrapolate that to “the earth was in the grip of….”

    Similarly the Permian deposits exposed south of Bermagui, NSW, OZ, would not lead one to conclude that “the earth was in the grip of….”.

    Sunny daytine Los Angeles is, so frigid McMurdo is too.

  3. TCO
    Posted Sep 21, 2005 at 12:41 PM | Permalink | Reply

    CLearly the time scales of glacier formation/decay are an issue as well as moisture versus temp issues. It would be nice to see someone skethc the problem conceptually.

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