The Glacial Mass Thinning Plot Thickens
This (only a blog) post adds to the growing mass of evidence that Western US glaciers, and many others, have NOT BEEN SHRINKING, lately. They are not even Thinning, lately. Nor are their Areas diminishing, lately. I add the “lately” caveat because of a later plot or two capturing nearby streamflow records going back to the late 19th century. But first, consider the featured animation I adapted from . It basically demonstrates the self-contradicting messaging from that Institute of Arctic and Alpine Research (INSTAAR) reference.
For example, the color map suggests that the 1999 extent (green) of the Arapaho Glacier outside of Boulder, Colorado, is the smallest of the three years considered, selected by the authors from over 100 years of data and papers. Yet an aerial photograph used within the same paper and well in context of the color map suggests that the 1999 extent is at least as large as the 1960 extent (yellow). If disoriented at all, focus on the magenta line. This is their glacier depth cross-section line D-D’
In these figures and numbers they apparently did account for everyday snow, versus actual glacier. The next image set also comes from their paper. It shows again how through this transect and others, although marginally thinner through the middle of 3 the 4 main cross sections, the 2005* glacier is often Thicker at each end, than the 1960 glacier. Note that for the D-D’ cross section, they do not bother to produce the thickness difference in their insert plot. Rather they only indicate that the glacier hasn’t thinned across that profile.
Not to quibble but those inset profiles are also interesting for another reason. They only show where Thinning has occurred. They do not highlight where Thickening has occurred, even though that can be as significant as any thinning magnitude. Perhaps I’m too generous because the D-D’ cross section actually indicates significant thickening. At least the larger curves are clear and so the figure contains some mixed messages.
The paper has an abundance of mixed-messages on this glacier, but the take-home message is one of imminent glacier decline. The abstract of the paper includes a statement that (my bold):
“If recent trends in area loss continue, Arapaho Glacier may disappear in as few as 65 years..”**
And the Conclusions section includes a similar statement that (my bold):
“If past trends continue, Arapaho Glacier could cease to exist in as few as 65 years.”
Whereas slightly buried within the text, I find claims such as (my bold):
“The uncertainty of average thinning measured along C–C9, 67.7 m, does not rule out the possibility that Arapaho Glacier’s thickness increased between 1960 and 2005.”
I hope this is clear to any as I think it is to me. The animation from their own plots contradicts their own statement that “Arapaho Glacier has shown a pattern of increasingly rapid area loss..” Rather, as shown above, Arapaho Glacier’s areal extent appears to be relatively stable. Moreover, there appears to be some actual thickening. If the area remains constant and the thickness increases, that nominally suggests that the volume of the glacier has slightly increased since 1960.
The related Denver Post story, 8 years after the study, only reports the alarming claims. All of the caveats and contradictions are now stripped from the nominal public view. The article does include a recent photo of the glacier, but so far as I can make from that far away photo, the glacier is as long as it’s ever been. Many climate change activists are no doubt very thankful to Reporter Jackson Barnett and original co-author of  Robert S. Anderson for straightening out and updating the scientists’ original mixed messages to align with their belief system.
A good precursor to this post comes from my previous post and it is recommended that you read that as well if you haven’t already.
It seems likely to me that glaciers are not as Anderson states in that Denver Post article, canaries in the coal mine. They appear if anything to follow the streamflow patterns in that area. I’ve taken the liberty of stringing together some local and regional streamflow records to explore this point. Pictured below is a very long time series record covering observed streamflows for the Green River near Green River Utah (GRnGRUT), and a shorter record for Clear Creek near Lawson, Colorado (CCnLCO). Then I’ve adapted some information from text and Table 1 of  in the magenta circles. Finally I’ve simply eyeballed their glacier photos from Figure 2, and worked from the above treatment to try to fill in a few blanks with the smaller filled magenta dots.
This is only an informal treatment after all. Clearly more and better data would add much value. There is little controversy that atmospheric moisture (and streamflows accordingly) in that Southern Rocky Mountain region, was very abundant in the early 1900s. The moisture forcing dropped thereafter and never fully recovered. The reference  does not explore this connection. Nor does the Denver Post article.
The general pattern shown in this figure does happen to support my emerging notion (not a belief, just a notion) that it is mainly the influence of atmospheric moisture which drives glacier advancements and retreats.
 (2010) Twentieth-century Changes in the Thickness and Extent of Arapaho Glacier, Front Range, Colorado, Arctic, Antarctic, and Alpine Research, 42:2, 198-209,
*The report may have an error in identifying 2005 vs 1999 given the context of the plot. For my purposes this does not impact in general. But as always it is important to know whenever a date inconsistency is identified.
**A common theme of alarming papers is a drastic projection which will not materialize until the authors can no longer be held accountable simply because of a typical human career span. For example, please consider the Massive Tree Mortality (MTM) topic within a recent post.
640total visits,7visits today