Glacier_Mass_Balance_Map.png
Summary
The effective rate of change in glacier thickness, also known as the glaciological mass balance , is a measure of the average change in a glacier's thickness after correcting for changes in density associated with the compaction of snow and conversion to ice . The map shows the average annual rate of thinning since 1970 for the 173 glaciers that have been measured at least 5 times between 1970 and 2004 (Dyurgerov and Meier 2005). Larger changes are plotted as larger circles and towards the back.
All survey regions except Scandinavia show a net thinning. This widespread glacier retreat is generally regarded as a sign of global warming .
During this period, 83% of surveyed glaciers showed thinning with an average loss across all glaciers of 0.31 m/yr. The most rapidly growing glacier in the sample is Engabreen glacier in Norway with a thickening of 0.64 m/yr. The most rapidly shrinking was Ivory glacier in New Zealand which was thinning at 2.4 m/yr. Ivory glacier had totally disintegrated by circa 1988 [1] .
Copyright
This figure was originally prepared by Rober A. Rohde from published data and is incorporated into the Global Warming Art project.
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Notes
This sample of mountain glaciers excludes the primary ice sheets of Greenland and Antarctica .
It should be acknowledged that glacier sampling is heavily biased towards North America and Europe . Africa has only a handful of glaciers, whereas continental Australia has none. However substantial unsampled mountain glaciers do exist in South America , Asia and the margins of Antarctica. Despite their importance, none of the marginal Antarctic glaciers have had their mass balance sampled at least 5 times since 1970.
These estimates of ice sheet thinning do not include glacier mass lost due to iceberg calving. Such calving is not significant for most mountain glaciers, since only a small proportion of these glaciers terminate in the ocean.
Reference
- Dyurgerov, Mark B. and Mark F. Meier (2005). "Glaciers and the Changing Earth System: A 2004 Snapshot". Institute of Arctic and Alpine Research, Occasional Paper 58 .
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