because accumulation exceeds ablation in a location. This
accumulation zone after it thickens to more than 30 m begins to
For a glacier to survive it must have a consistent and
persistent accumulation zone. To diagnose a glacier that is
disappearing look for 1) Emergence of rock outcrops in upper
region of the glacier. 2) Recession of the margin of the glacier
in upper reaches of the glacier. 3) Lack of consistent snowcover
at the end of the summer in the accumulation zone of Published
Paper in The Cyrosphere 2010 Quaternary International Paper 2011
Why these criteria? Glaciers respond to climate in an attempt to
achieve equilibrium. A glacier advances due to a climate
cooling/snowfall increase that causes positive mass balance. A
climate warming/snowfall decrease leads to negative mass
balances and glacier retreat. To reestablish equilibrium a
retreating glacier must lose enough of its highest ablating
sections, usually at the lowest elevations, so that accumulating
snows in the near the head of the glacier