surface mass balance

Surface mass balance refers to the difference between the snowfall that adds mass to a glacier or ice sheet and the melting, sublimation, or calving that removes it over a specific period. Essentially, it measures whether a glacier is gaining or losing ice at its surface. A positive balance means the glacier is growing, while a negative balance indicates it is shrinking. This concept helps scientists understand how climate change impacts glacier stability and sea-level rise by tracking ice accumulation and loss over time.