Home > paleoclimate > Mann 2007 SI Fig 5 and Antarctic Volcanic Sulfur

Mann 2007 SI Fig 5 and Antarctic Volcanic Sulfur

2010 July 15

Jeff Id had a post up at tAV that was taking a preliminary look at Mann 2007 SI Fig 5. I’m no paleo-guy, but there was this strong dip in the early 19th Century with its obvious relationship to the Tambora volcano.

I was curious about the other dips. A quick google search yielded A 4100-year record of explosive volcanism from an East Antarctica ice core by Cole-Dai, 2000, from which I graphed the first 19 events. Cole-Dai includes many more events, but those predate the time scale on Mann 2007. On the other hand, there are other volcanic events in other records listed in the paper which correspond to the mid-11th century dips. Here is the Cole-Dai “Plateau Remote” volcanic events with the tick marks roughly scaled logarithmically to the size of the sulfur emissions.

mann07-si-fig5-coledai-volcano.jpg

A 4100-year record of explosive volcanism from an East Antarctica ice core

Extensive archives of volcanic history are available from ice cores recovered from the Antarctic and Greenland ice sheets that receive and preserve sulfuric acid fallout from explosive volcanic eruptions. The continuous, detailed (average 1.2 samples per year) sulfate measurements of a 200-m ice core from a remote East Antarctica site (Plateau Remote) provide a record of Southern Hemisphere volcanism over the last 4100 years. This extends the volcanic record beyond the last 1000 years covered by previous Antarctic ice cores. An average of 1.3 eruptions per century is recorded in East Antarctic snow during the last 4100 years. The record shows that on average eruptions have been more frequent and more explosive during the most recent 2000 years than in the previous 2100 years. Intervals up to 500 years are observed in which few explosive volcanic signals are detected. These periods include 2000–1500 B.C. (no eruptions), 500–1 B.C. (two eruptions), and 700–1200 A.D. (two eruptions). This new Plateau Remote volcanic record is compared with those from previous Antarctic ice cores covering the last 1000 years. In terms of dates for volcanic events, the new record is in excellent agreement with the earlier records. However, significant discrepancies are found between these records in relative signal magnitude (volcanic flux) of several well-known events. The discrepancies among the records may be explained by the differences in the glaciology at the ice core sites, analytical techniques used for sulfate and sulfuric acid measurement, and the selection of detection thresholds for volcanic signals. Comparison with Greenland ice core volcanic records indicates that during the last millennium, nine large, low-latitude eruptions contributed significant amounts of volcanic aerosols to the atmosphere of both hemispheres, potentially affecting global climate. In contrast, only one or possibly two such eruptions are found in the first millennium A.D.

http://www.agu.org/pubs/crossref/2000/2000JD900254.shtml

Citation: Cole-Dai, J., E. Mosley-Thompson, S. P. Wight, and L. G. Thompson (2000), A 4100-year record of explosive volcanism from an East Antarctica ice core, J. Geophys. Res., 105(D19), 24,431–24,441, doi:10.1029/2000JD900254.

A snip of the top of the chart …
cole-dai-2000-volcano.png

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  1. 2010 July 15 at 8:29 pm

    Thanks for plotting the sulfates to scale. Very nice!

  2. 2010 July 16 at 5:50 am

    Thanks. My very first paleo-post.

    If I understand Mann 07 correctly, the plots are based on pseudo-proxies generated from models. So seeing the volcanoes in the data is really just confirmation that volcanoes are being fed into the models forcing scenarios.

    Turn to the real proxy composites, and it seems a lot of this is washed out in the smoothing. Something to keep my eye on while I learn more.

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