Causes of Glacial Retreat.
Global warning always seems to get the blame for glacial retreat, but there is evidence that it is not the only cause.
On a mountaineering trip 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 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 horizontal water channels that had originally been built to take glacial melt water to nearby villages.
- Glaciers at 18,000 feet were bone dry, totally without snow. Twisted upwards pointing fingers of ice were widely encountered on these high glaciers, some up to 5 inches tall.
- There were no clouds, there was no 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.
Our conclusion was that the glacial retreat we had encountered was not due directly to global warming, but to a long-term lack of clouds, needed to slow evaporation and to cause precipitation.
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