During the last glacial maximum, the Bohinj Glacier extended through the Vrata Valley and across Dežela to the gates of Radovljica. This (great) glacier experienced its own critical decline periods during warmer interstadials. The former Triglav Glacier was not a direct successor to that immense ice stream. Triglav Glacier (known traditionally as Zeleni sneg / Green Snow, named for the bluish-green tint of its dense ice) was once the largest glacier in Slovenia. The former remnants of the glacier were situated on the northeastern slope below the summit of Triglav on the Kredarica plateau, but today they no longer exist.
In the 16th century, the extent of Triglav Glacier was smaller than in 1957. This conclusion is drawn from records in the High Tauern, where miners excavated gold and silver along glacier margins during the 1500s before the adits were once again engulfed by advancing ice. In Slovenia, systematic monitoring of glaciers was initiated in 1946 by the Institute of Geography of the Slovenian Academy of Sciences and Arts (SAZU).
Due to its altitude, Mount Triglav and the Triglav Glacier were the sole locations suitable for observing the equilibrium snowline. The snowline is never permanent; rather, it fluctuates across distinct climatic intervals. In 1955, surveyors encountered dead ice beneath surface morainic debris and determined that the glacier had spanned that full perimeter approximately eighty years earlier (Gams). Between 1946 and 1952, its surface area hovered between 13 and 16 hectares.
It was established that glaciers receive up to 80% of the energy necessary for melting through solar insolation. Glaciers recede primarily during clear, sunny, and hot summers, while they advance during overcast, humid, and cool summers. The growth or deficit of glacial volume depended directly on the balance between accumulated snow and melted ice. Mount Triglav was assigned a theoretical equilibrium snowline at an elevation of 2,700 meters.
During the cooler climatic anomaly known as the Little Ice Age (mid-19th century), the glacier covered approximately 40 hectares. Even toward the end of the 19th century, Triglav Glacier remained a genuine, dynamic glacier featuring substantial ice thickness, internal plastic flow, and prominent crevasses. In recent decades, however, the drastic drop in October snowfall—traditionally the beginning of the accumulation season—accelerated its decline. Increased summer rain instead of snow, higher temperatures during the ablation season, and extended solar radiation triggered intense retreat after 1983 and fragmented the body into separate sections after 1991.
From a glaciological perspective, Triglav Glacier permanently lost its status as a true glacier by the end of the 20th century (after 1999). Following the loss of critical mass, the cessation of plastic ice deformation, and the total disappearance of crevasses, it transformed into a glacioid or stagnant ice apron (firn field) lacking any internal flow dynamics. In recent years, successive record-hot summers and arid winters melted away the final patches of dead ice, reducing its surface area to 0 hectares. With its total disappearance and the parallel demise of the glacieret beneath Mount Skuta, Slovenia no longer has any active glaciers.