Upper Engadine, Switzerland · 1877–2025
The Morteratsch Glacier on every Swiss map since 1877
Swiss surveyors have mapped this glacier again and again since 1877, and measured its front almost every autumn since 1878. Here are 18 editions of the national map and a 2025 aerial photograph, laid over the mountain as it stands today, with the measurements beneath them.
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The first precise map
On the Siegfried map in print in 1877, the Bernina sheet of that year with the St. Moritz sheet of 1875 to the north, the ice fills the valley floor below Piz Bernina, at 4,049 m the highest summit of the Eastern Alps, and its tongue reaches down into the larch forest.
Every map here lies on the ground as it is today, so the old ice is drawn on a valley floor that in 1877 lay beneath it.
The ice front was a place people walked up to.
Measured almost every autumn
In the autumn of 1878 the position of the glacier’s front was measured for the first time. Since then it has been measured again almost every year. The record is kept by GLAMOS, the Swiss glacier monitoring network: 137 measurements, with one year, 1893–94, missing.
3,059 mmeasured retreat of the front, from autumn 1878 to October 2024The old maps lag behind the ice
The Bernina sheet was reprinted in 1887, 1896, 1909, 1925 and 1938; the St. Moritz sheet, which holds the end of the tongue, in 1896, 1908, 1925 and 1938. In 1887 the end of the tongue was still on the 1875 sheet, and on the 1909 and 1938 editions it looks as it did on the editions before. Press the play button to step through them.
Over those sixty years, from 1878 to 1938, the measured front retreated 683 m.
A new map, and the fastest retreat of the 20th century
From 1950 the new national map replaced the Siegfried sheets, at 1:50,000, then at 1:25,000: the St. Moritz sheet from 1958 and the Piz Bernina sheet from 1964. The style of drawing changes with it: the blue contour lines on the ice are a new way of drawing it, not new ice.
The front retreated 261 m in the 1940s, 282 m in the 1950s and 318 m in the 1960s, more in each decade than in any decade before.
A pause
Then the retreat slowed: 141 m in the 1970s, 85 m in the 1980s. In 1985 and 1988 the front was even found a few metres further down the valley than a year before, 8 m and 2 m.
Small advances like these were also measured in 1899, 1912 and 2004. None of them lasted.
The fastest decade on record
In the 2010s the front retreated 606 m, nearly twice as much as in any decade before. The two largest retreats in a single year were measured in 2015, 164 m, and 2016, 135 m.
On the 2015 edition the tongue has pulled far back up the valley, and the stream runs where the ice was.
Today, with the ice of 1850
This is the aerial photograph swisstopo took in 2025. The white line is the glacier around 1850, at the end of the Little Ice Age, reconstructed from old maps and from the moraines the ice left behind. Then the ice ended less than half a kilometre from Morteratsch.
In 2025 the tongue was already free of snow in June. Across Switzerland, glaciers lost more than 5% of their volume in 2026, and nearly a fifth in five years.
How far has the front retreated since the year you were born?
Type a year: the year you were born, or a year you stood in this valley. The sum runs from that autumn to the last measurement, in October 2024, and the mountain shows the map published closest to it.
