How do polar glaciers differ from temperate glaciers?

Glaciers are classified by their thermal condition, which dictates how they accumulate mass, lose mass, and transform snow into ice. The primary differences between polar and temperate glaciers are as follows:1

• Thermal State: A polar glacier remains below the freezing point throughout its entire mass for the whole year. In contrast, a temperate glacier exists at the melting temperature throughout its mass, though its surface may freeze during winter.1
• Mass Loss (Ablation): In temperate regions, surface melting is the predominant process for removing glacier mass. In polar regions, calving—the breaking off of icebergs—is typically the most significant process for mass loss.1
• Energy Balance: For temperate glaciers, solar radiation is usually the primary heat source, and most heat loss is directed toward melting ice. In polar regions, while solar radiation remains a primary heat gain, heat loss occurs through outgoing long-wavelength radiation, and heat conduction from lower layers plays a more significant role in the glacier's energy balance.2

These thermal differences mean that temperate glaciers act as complex reservoirs that store and release liquid water seasonally, whereas polar glaciers are characterized by their consistently frozen state.13