Explain how the mass balance of a glacier can be an indicator of climate change.

The ELA (Equilibirum Line Altitude) of a glacier identifies the point at which the ablation and accumulation zones are balanced, meaning the mass balance of the glacier is at equilibrium. The altitude of this line changes when either the rate of accumulation or ablation changes, so the position of the ELA becomes a measure for the mass balance of a glacier. For example, if the temperature increases and the ablation rate increases then the ELA will rise as a larger proportion of the glacier melts, and the mass balance decreases. In contrast, in winter when accumulation increases the ELA will get lower, towards the tongue of the glacier, as the mass increases. As climate change acts to increase temperatures, it has been identified that glaciers are melting faster as a result. The ELA can be used as an indicator of this climate change by tracking its location, therefore showing how the rate of ablation as a function of temperature change is increasing. Furthermore the rate at which the ELA rises will indicate not only that climate change is happening, but at what speed. This is vital information for projecting future impact assessments.