Hanrahan, this event is often cited as evidence against global...

  1. 705 Posts.
    Hanrahan, this event is often cited as evidence against global warming but what it is is evidence of how glaciers and ice sheets work.

    Glaciers are quite accurately described as "rivers of ice". When snow falls in most places, it completely melts during the course of a season. However in some places it doesn't melt or evaporate away but accumulates year on year, gradually compacting and turning to ice. This ice will flow downhill under gravity, perhaps for hundreds of kilometres. Eventually the glacier will either melt away or bits will break off the end and float away as icebergs. This is hat would have been going on under the aircraft stranded on the Greenland ice sheet. The snow falling over the planes would be replacing ice flowing away from underneath. The balance between accumulating snow and flowing ice can be determined in a number of ways.

    The easiest to understand is observing the tongue of the glacier. Advancing and the glacier is getting bigger. Retreating and the glacier is getting smaller.

    The most useful measurement, but one we don't have for the plane site, is the thickness of the ice sheet. If your conjecture were true this total thickness would be increasing. However, total thickness must be measured to the base of the glacier, not to the slowly sinking planes.

    The most convenient for us is to access the GRACE satellite data to see if the total mass of a glacier/ice sheet is increasing or decreasing. GRACE satellite data shows that the Greenland Ice sheet is shrinking.
 
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