A glacier in British Columbia has calved what one scientist has called "certainly ... the largest iceberg I've ever seen in Canada," and a "highlight example" of the impact on glaciers of climate change.
The exact date of the calving is unknown, but it was discovered when Dr. Mauri Pielto, professor of environmental science at Nichols College in Massachusetts and director of the North Cascade Glacier Climate Project, examined a photograph of the glacier taken when the NASA Earth Observations (NEO) satellite passed over the area on Aug. 27.
"I knew it would be a good time to look at the glacier," he told the Globe and Mail. "I hadn't looked in maybe two years at the satellite imagery at the end of [the glacier tongue], and it looked poised for a breakup. So I looked."
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Writing on the blog of the American Geophysical Union, Pielto describes the Porcupine Glacier as a 12.5-mile-long outlet glacier of an icefield in the Hoodoo Mountains of Northern British Columbia. The glacier terminates in a lake, as you can see in the photograph above, a false-color rendering of the satellite image.
In 1988 the glacier's tongue reached to within a mile of the far shore of the lake. By 1999 this tongue had narrowed and retreated into the wider portion of the lake. In 2011, it collapsed. By 2015 the glacier had retreated 2 miles from the 1988 location. Over the next 12 months, it retreated another mile, mostly due to the calving of the iceberg, which measured just under half a square mile.
Pielto noted that the pace of the retreat will almost certainly slow once the glacier reaches the head of the lake, and becomes grounded on bedrock rather than floating on water.
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What is happening to Porcupine Glacier is, he says, just an extreme example of what is taking place to a multitude of glaciers in the region.
"I could list 100 glaciers that are doing a similar thing in terms of the rate of retreat in the last 20 years, that are within a couple hundred miles of that location," he said. "I have worked on over 200 glaciers just in that area, and all but one have been retreating."
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