FW: how many glaciers--answered!--addendum

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FW: how many glaciers--answered!--addendum

Bindschadler, Robert A. (GSFC-614.0)[EMERITUS]

All,

 

Just a short addendum to my “how many glaciers” question posted yesterday.

 

A good resource Mauri Pelto pointed me toward is: http://www.grid.unep.ch/glaciers/

 

And finally, I would be remiss not to mention the IGS Symposium on the World Glacier Inventory in 2009 (thanks Simon Ommanney).  IGS published a papers volume (Annals of Glaciology Vol.50, #53) and below I copy the abstract from Ohmura’s final paper in that volume.  If I take his statement that the incomplete portion of the inventory of 46% equals about 95,000 glaciers, then the full inventory comes in at just over 200,000 glaciers.   I think this is the number and the reference that I will use. 

 

Thanks to everyone who has contributed to this exchange!

 

Bob

Completing the World Glacier Inventory

Atsumu OHMURA

Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology (ETH), CH-8092 Zu¨ rich, Switzerland

E-mail: [hidden email]

ABSTRACT. An inventory of the surface area and volume of the world’s glaciers, outside Greenland and

Antarctica, was part of the International Hydrological Decade (1965–74). It was considered essential to

an understanding of the role played by glaciers in the hydrological cycle and was to be repeated every 50

years to detect change. To date, 46% of the estimated total glacier area has been inventoried and made

available through theWorld Glacier Monitoring Service and the US National Snow and Ice Data Center.

As the original inventory method was too time-consuming and inapplicable for some areas, a simplified

method was developed in the early 1980s using satellite images. The Global Land Ice Measurements

from Space (GLIMS) project now covers 34% of the estimated glacierized area outside Greenland and

Antarctica. Both inventory efforts have made good progress and contributed substantially to our

knowledge of glaciology and its related sciences, but global coverage is still incomplete. If both

inventories are combined, 46% of the world’s glacierized area is still missing; 26% is covered by both

methods, which allows the quality of the satellite-based and semi-automatic inventories to be assessed

by comparison. About 95 000 glaciers remain to be inventoried, of which about half are in the Canadian

Cordillera, South America and the Canadian Arctic Islands. As the cryosphere is changing rapidly, it is of

the utmost importance to complete the global glacier inventory as soon as possible, and identify an

appropriate repeat cycle.

 

+++++++++++++++++++++++++++++++++++++++++

Dr. Robert Bindschadler

Emeritus Scientist

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

 

From: [hidden email] [mailto:[hidden email]] On Behalf Of Bindschadler, Robert A. (GSFC-614.0)[EMERITUS]
Sent: Monday, August 30, 2010 2:40 PM
To: [hidden email]
Subject: [CRYOLIST] how many glaciers--answered!

 

Cryolisters,

 

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.

Better ask Dave though!

Reference:
Bahr, D. B., M. Dyurgerov, and M. F. Meier (2009), Sea-level rise from glaciers and ice caps: A lower bound, Geophys. Res. Lett., 36, L03501, doi:10.1029/2008GL036309.

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 you want.

I certainly got what I need—and more!

Bob

+++++++++++++++++++++++++++++++++++++++++

Dr. Robert Bindschadler

Emeritus Scientist

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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