Gorner Glacier

Glacier on the Monte Rosa massif

The Grenzgletscher between the central Monte Rosa massif and the Liskamm to the south is nowadays the main contributor to the lower Gorner Glacier. The Gorner Glacier's upper part is almost already disconnected from its lower part. The former tributaries Breithorngletscher, Triftjigletscher, and Unterer Theodulgletscher lost their connections to the Gorner Glacier during the twentieth century; the Unterer Theodulgletscher became disconnected in the 1980s. A notable feature of this glacier is the Gornersee, an ice marginal lake at the confluence area of the Gorner Glacier and Grenzgletscher. This lake fills every year and drains in summer, usually as a glacial lake outburst flood. This is one of only a few glacial lakes in the Alps exhibiting this behavior. There are also notable surface features including crevasses and "table top" forms where large surface boulders have been left stranded above the glaciers surface. These tabular rocks are supported by ice that the boulder has sheltered from melting that has affected the more exposed surrounding ice. The glacier is the source of the river Gornera, which flows down through Zermatt itself. However, most of its water is captured by a water catchment station of the Grande Dixence hydroelectric power plant. This water then ends up in the Lac des Dix, the main reservoir of Grande Dixence. The glacier as well as the surrounding mountains can be seen from the Gornergrat , connected from Zermatt by the Gornergrat Railway.

Like almost all other glaciers in the Alps, and most glaciers on the globe as well, the Gorner Glacier is retreating as a result of global warming—in this case, dramatically so. As of 2014, Gorner Glacier had been retreating about every year, but with a record loss of in 2008. Since its last major expansion (in the modern era, after the last glacial period) in 1859, it had lost more than in distance. As of about 2015, the Gorner Glacier had retreated to the point where it lost touch with its main tributary: the Grenzgletscher on the south side of the Monte Rosa massif. The Gorner Glacier proper is found on the north side. Now the prominent flow visible from Gornergrat is properly called the Grenzgletscher and can no longer be considered part of the Gorner Glacier. The Monte Rosa Glacier in the middle has also lost touch with the Gorner Glacier. This can be seen in a comparison of photographs over the years: