I’ll start by thanking Todd Albert for maintaining Cryolist. It made this soooo easy.
Todd asked me to compile the responses that I received and share it with the list.
After just a few hours, here were the most informative replies (minus the many that quickly steered me toward the Bahr & Dygerov reference with the figure of 160,000 glaciers in it). Thanks to everyone!
1--from Hester Jiskoot
For a number of years now I have been using the rough number of 160,000 based on Bahr and Dyurgerov (1999).
In my PhD thesis from 1999 (see Table 1.1 on p. 7 and 8: http://people.uleth.ca/~hester.jiskoot/pages/publications/Jiskoot_H_PhD_1999.pdf) I verified their number based on counting and extrapolation of a published glacier numbers estimated around the world. The total number of glaciers I calculated from the sum of all regions was 157122, very close to the Bahr and Dyurgerov estimate. This number includes an estimate of Antarctic peninsula local ice that is half the number of the local glaciers around the Greenland Ice Sheet.
The above total glacier number include all glacier types (incl. rock glaciers, neves, etc). I also roughly estimated on the basis of the distribution of 'true' glaciers (mountain glaciers and up) by excluding glaciers smaller than 1km2 in a number of regions (e.g. Svalbard and the Yukon Territory) that the total number of glacier >1km2 is about 50% of 160 000. On the basis of the above calculations in my PhD thesis I did publish a number of "more than 100,000 glaciers world-wide" in Jiskoot et al. (1998).
Bahr, D.B., and Dyurgerov, M.B., 1999. Characteristic mass-balance scaling with valley glacier size. J. Glaciol. 45 (149), 17-21.
Jiskoot, H, P Boyle & T Murray, 1998. The incidence of glacier surging in Svalbard: results from multivariate statistics. Computers and Geosciences 24 (4), 387-399.
2—from Jeff Key ( I like it because it reminds us all of the IGOS Cryosphere volume)
In our IGOS Cryosphere Theme report there is a statement that "The total number of glaciers has been estimated by statistical scaling to about 160,000 (Meier and Bahr, 1996), covering an area of about 785m999 km2 (Dyurgerov and Meier, 2005)". The Meier and Bahr reference is a CRREL Special Report, 96-27, 98-94, "Counting Glaciers: Use of scaling methods to estimate the number and size distribution of the glaciers of the world". The other reference is Dyurgerov, M.B. and M.F. Meier, 2005, Glaciers and the changing earth system: a 2004 snapshot", INSTAAR Occasional Paper, OP-58.
3—from Tad Pfeffer
The answer obviously depends on what
lower size limit you choose, but the largest number that gets quoted is 200,000
- 400,000 glaciers, with a cutoff at 1 km^2. Bahr and Meier (2009) use this,
quoting Dyurgerov and Meier's INSTAAR Occasional Paper #58 (2006).... but, I
can't actually find the number in Dyurgerov and Meier. You might contact Dave
Bahr <[hidden email]> about
this (I actually had exactly this conversation with him the other day). Other
analyses suggest that there are an enormous number of uncounted glaciers, and
it's pretty easy to get up to ca. 200,000 with conservative estimates.
4—from Jason Box (not actually the answer to the question I asked, but interesting numbers, so I added it)
Based on MODIS data, I calculated
0.389 million sq km isolated ice masses in Greenland of at least 0.0625 sq km
in area totaling 69,489 sq km outside the inland ice sheet, total glaciated
area: 1.818 million sq km. The work is unpublished :-/ but use the numbers if
I certainly got what I need—and more!
Dr. Robert Bindschadler
Hydrospheric and Biospheric Sciences Laboratory
Code 614 Bldg. 33, Rm. A112
NASA Goddard Space Flight Center 301-614-5707
Greenbelt, MD 20771 301-614-5666 (Fax)
USA [hidden email]
"None of us is as smart as all of us." Japanese proverb
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