Glaciers in summer

A glacier is a huge, flowing stream of ice. It forms in high mountains when, over the course of decades, more snow falls than melts in summer. Due to its enormous weight, the old snow (firn) in the so-called glacier head is compressed into dense glacier ice, which eventually slides very slowly down towards the valley.

Glaciers cover around 10 per cent of the world’s land area. Over 99 per cent of the ice is found in the vast ice sheets of Antarctica and Greenland. The remainder consists of mountain glaciers, which can be found on almost every continent – from the Alps here in Austria to the Himalayas in Asia and the Andes in South America.

The characteristic blue colour is caused by the extreme pressure inside: the air is completely squeezed out of the ice, causing it to refract sunlight and reflect only the blue spectrum. Crevasses, in turn, are formed by the constant movement of the ice mass, which comes under immense strain as it flows over uneven rocky ground and splits open at the surface.

Lossofdistance: On average over recent years, the glaciers monitored in Austria have lost between 15 and 25 metres of distance per year. In extremely hot years (such as 2022 or 2024), individual glacier tongues have even shrunk by over 100 metres in just twelve months.

Thicknessloss: People often focus solely on how much shorter a glacier is becoming. However, the ‘subsidence’ is far more dramatic. In summer, glacier surfaces often lose 2 to 4 metres of ice thickness per year – across their entire area.

One thing that stands out about glacial rivers is that the water is not clear, but has a milky-grey, cloudy appearance. This is what is known as ‘glacial milk’. The cloudiness is caused by finely ground rock dust, which the heavy glacier grinds up as it moves over the rocky bed. It is best not to drink this water. Although it is not poisonous, the fine rock dust is extremely hard on the gastrointestinal tract. 

The ice and the remaining old snow act like a giant mirror. They reflect up to 80 per cent of UV radiation. At the Glacier Ski Resort, you are therefore exposed to UV radiation from above and below at the same time. Sun cream with SPF 50+, lip balm and high-quality sunglasses (category 3 or 4) to protect against snow blindness are essential items to pack.