Causes of Glacial Retreat.
Melting ice always seems to get the blame for glacial retreat, but there is evidence that it can be due to evaporating ice.
On a mountaineering expedition to the Bolivian Andes in 1992, it was obvious that the glaciers had retreated significantly from where their snouts were depicted on the maps. These are the obvious symptoms that we easily spotted:
- The recorded rainfall in the area was just a few millimetres per annum.
- The mountains were on the edge of the altiplano, at 3,600m, the highest desert in the world outside of Tibet.
- There was virtually no water flowing from the snouts of the receded glaciers.
- Near two glacial snouts we found the remains of long dried out levadas (horizontal water channels) that had originally been built to take glacial melt water to nearby villages.
- Glaciers (such as the one in the photo below at 6,600m amsl) were bone dry, totally without snow. Twisted upwards pointing fingers of ice were widely encountered on these high glaciers, as you can see.
- There were few clouds, no noticeable wind, and we were at very high altitude in the tropics, resulting in a very strong sun. From this, it seems obvious that the evaporative loss of ice from high altitude glaciers must surely be quite significant.
’Neve Penitenta’ at 6,552 metres
Our conclusion was that the glacial retreat we had encountered was not due to ice melting, but to it evaporating.
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