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At Roger Pielke Sr.'s blog entry:

As discussed on Climate Science, when climate metrics are investigated in detail, the reality of the real world often conflicts with the pronouncements of the climate assessments. With respect to glaciers, this mismatch between reality and the assessments has been presented before (see and see).

The weblog for today provides yet another example of the incomplete information that is being communicated to policymakers and others.

An article in the November-December 2006 issue of the Earth Observer entitled “The GLIMS Glacier Inventory of the Antarctic Peninsula” by Frank Rau,  Jeffrey S. Kargel,  and Bruce H. Raup provides an update on the recent behavior of glaciers in the northern Antarctica peninsula (see the November-December pdf on pages 9-11). This is a region where significant regional surface temperature warming has been recorded.

An excerpt from their article, however, shows that the response of the glaciers is more complex in response to this reported regional warming. They write,

“Analysis of high resolution ASTER data co-registered to Landsat Thematic Mapper ™ and Enhanced Thematic Mapper Plus (ETM+) data provide information on glacier front variations between the years 1986 and 2002. In regional case studies, more than 300 glaciers were examined, covering a variety of glacial systems distributed over the northern Antarctic Peninsula. Of these, only 40 (12.8%) displayed advancing glacier fronts accounting for a gain of 7.1 km², while 171 (54.6%) showed retreating ice fronts accounting for a loss of 146.1 km². In addition, 102 (32.6%) were found to be in invariant conditions. The glaciers examined displayed no indications of dynamic flow instabilities. The observed glacial variations are therefore interpreted as direct consequences of the rapidly changing climatic conditions in the region that are affecting accumulation and ablation.

Beyond the overall trend toward retreating ice fronts, observations dating from the mid 1980s to 2001 reveal different patterns of glacier variation across the Antarctic Peninsula. An area of significant retreat is concentrated on the northeastern sectors of the peninsula-- eastern coast of Trinity Peninsula and James Ross Island. Similarly, a consistent distribution of predominant glacial recession is also identifiable along the southwestern coasts of the study area--Graham Coast, Loubet Coast and Marguerite Bay. Thisis in sharp contrast with glacier frontal positions recorded in northwestern parts of the Antarctic Peninsula adjacent to Bellingshausen Sea, where only slight recessions and minor advances were recorded--western coast of Trinity Peninsula and Danco Coast. These observations from the northwest, which are presumed to be in the natural range of frontal fluctuations of tidewater glaciers, suggest relative dynamic stability of the glacial systems in this sector.”

This article indicates that 45.4% of the glacier fronts are either advancing or are invariant over the period from the 1980s to 2001. While the retreating glaciers have lost more area than has been gained by the advancing glaciers, this also need to be placed in context of the total area of the glaciers in this region (which was not done in this article).

Nonetheless, even without that information, the general message that glaciers are receding almost everywhere is clearly not accurate when the data is evaluated in detail.

by Nomad (Bjinse) on Mon Feb 12th, 2007 at 04:16:10 AM EST

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