The Beauty of Glaciers

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I recently took a wonderful cruise in Alaska and observed some of the earth’s largest glaciers.  A glacier is a huge buildup of ice and rock sediment that accumulates slowly by the compression of snow.  Although they appear to be solid ice, glaciers flow very slowly, from tens of metres to thousands of metres per year.  The record for the fastest glacial movement is held by the Kutiah Glacier in Pakistan, which raced more than 12 kilometres in three months.

Glaciers store about75% of the earth’s fresh water, and cover10% of its land mass.  If all the land ice melted, sea level would rise some seventy metres, world wide.

For a glacier to form, the temperature must be low enough for snow to build up, and snow precipitation must be constant enough for the accumulation of ice to be greater than the loss of ice through melting, evaporation and calving, which is the loss of ice from the base of the glacier.

Glacial ice often looks blue.  This is because years of compression causes the ice crystals, some of which may be as large as tennis balls, to become very dense, as tiny air pockets between the crystals are forced out.  This dense ice absorbs all the colours in the spectrum except for the blue, which is the colour we see.  When glacial ice is white it is because there are still many tiny air bubbles in it.

So next time you run out of ice, remember there’s still plenty out there - in glaciers.