A bit sideways, this one, but just something I noticed. Here is a new paper (under discussion), from The Cryosphere. The subject matter is the mass balance of the McCall glacier, Alaska.

The paper is interesting in itself, and at only 25 pages, worth a read, not least for the work on internal accumulation and its relation to mass balance, which seems to be quite original.

But the main reason for posting it id to draw your attention to the graphics in the latter part of the paper.  No surprise to learn that the glacier has been shrinking for some time now (100 years, in total), nor that the rate of change of mass balance has accelerated since the 1980′s.  What is interesting is that the graphs bear an uncanny resemblance to others I have seen recently, such as the ones showing long-term ice extent trends for the Arctic on Cryosphere Today.

In fact, the shape of the graph is similar to very many of those showing changes related to climate in the Arctic. On the principle that coincidence may be plausible for two discrete measurements, but not for a whole set, it may be acceptable to conclude – tentatively – that the consistency carries for a number of measures and data. This, again, probably comes as no surprise to those of you who observe the progress of the Cryosphere.

But it does have implications. The shape is suggestive of the first part of a hyperbolic curve, where increase goes from negligeable, to noticeable, to substantial, in a logarithmic (?) relation. The question we could be asking, then, is whether the line of best fit for likely future changes in glacier mass balance, sea-ice area, GIS mass balance, should continue along this curve.

I cannot say that this should be the case, nor claim that it is likely, but it is plausible. If so, this suggests that the impacts of climate change for glaciers, sea ice, and other elements of the cryosphere, is starting to accelerate rapidly. This in turn has implications for the estimates of 21st Century sea level rise, and also for water resource availability in the next ten-twenty years.

I would be interested to know if there are scientists out there, or knowledgeable amateurs, who are willing to speculate that this is the case, and, if so, what the implications might be.

If you decide to post a comment, it won’t go up ’til Sunday, as I’m off line for two days, but don’t let that stop you if the mood takes you: I’ll update as soon as I get back.

Enjoy the weekend.

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