Tuesday, October 13, 2009

Nothing new under the sun

Bret has taken on the not-quite-latest religion: AGW.

That reminded me of a recent trip to Exit Glacier, which due to Climate Change has been receding for the last fifty years. And, for what must be entirely unrelated reasons, had been receding just as quickly for at least 150 years prior to that:

Click on the image for better resolution

Each of the squiggly white lines in the image represents a terminal moraine; that is, a mound of glacial debris left at each pause in a glacier's retreat. The oldest* moraine, from 1815, is well out into the valley. In the next 100 years, the glacier retreated roughly half the distance (and likely more than half the volume change) to its present location.

The same is true for nearly all glaciers in Southeast Alaska and neighboring Canada.

So what natural process ended in 1950, to be replaced by AGW?

Glaciers have a terrible, implacable beauty. They are extremely dangerous.

It is also worth noting that there is probably no environment on earth deader than a glacier. There is only one life form of any note: glacier worms that look like short pencil scriggles, and appear to feed on pollen blown onto the glacier.

Consequently, I have a tough time seeing how the warming of the last 200 years has had any negative effects whatsoever.

Never mind apocalypse.

Glaciologists are able to date terminal moraines by well defined arboreal forest succession stages out to about 200 years. Each of the white lines in the photo is dated by how long it takes for the differing forest type to appear.

Trimlines (think bathtub ring, but in this case the high-ice mark below which the glacier sheared everything) on either side of Exit Glacier's valley show that not only has the glacier retreated, it has also lost a great deal of depth.


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