What do you understand by "Glacier mass balance"? While elucidating the factors that affect the Glacier mass balance, discuss its implications for geography and environment.

Glacier Mass Balance is the gain and loss of ice from the glacier system. When glaciers lose more mass than they receive, it will be in negative mass balance and so will recede. When glaciers gain more mass than they lose, they will be in positive mass balance and will advance. Whereas, when Glaciers gain and lose approximately the same amount of snow and ice, they are considered as ‘in equilibrium’, and will neither advance nor recede.
In simple words, glacier mass balance is the quantitative expression of a glacier’s volumetric changes through time.
The factors affecting the Glacier Mass Balance are-

• Temperature.  
• Precipitation.
• Ablation (includes surface melt, surface melt water runoff, sublimation, avalanching and windblown snow)

The implications of glacier mass balance on geography include-
Glacial accumulation- This results into water input to a lake, which includes processes such as precipitation and water carried into the lake by streams, rivers, and groundwater channels.
Glacial ablation- This results into water removal from a lake, which includes processes such as evaporation, water carried out of the lake by streams, rivers, and groundwater channels, and extraction by humans.
With respect to its implication on environment, it is significant from the point of view melting of glaciers which would result into global warming and a major cause of concern for climate change.