Morteratsch Glacier Deep Dive
Morteratsch Glacier descends from the Bernina massif in the canton of Graubunden in southeastern Switzerland, flowing northward from the ice fields below the Bernina summit plateau through a wide glacial valley that opens toward the Engadin valley and the village of Pontresina. It is one of the longest and most voluminous glaciers in the Alps, and it has been the subject of continuous scientific monitoring since the late nineteenth century, making it one of the most thoroughly documented glaciers anywhere in the temperate zone.
For visitors, Morteratsch is also one of the most accessible significant glaciers in the Alps. A marked trail from the Morteratsch railway station — served by the Rhaetian Railway's Bernina line, itself a UNESCO World Heritage route — leads up the valley floor through the glacier's proglacial forefield, past stakes marking the position of the terminus in each decade of the twentieth and twenty-first centuries. This walk is both a scenic hike in spectacular mountain terrain and a vivid, physical lesson in glacier retreat.
Geography and Ice Field Context
Morteratsch Glacier covers approximately 15 square kilometres and descends from an ice field at approximately 3,200 to 4,000 metres above sea level to a terminus that, as of the early 2020s, stands at roughly 2,100 metres. The accumulation zone is connected to the Persgletscher, a tributary flowing from the south below Piz Bernina (4,049 m), the highest peak in the Eastern Alps. Other tributaries drain ice from Piz Palü (3,901 m) and Piz Zupò (3,996 m) on the southern rim of the ice field.
The glacier occupies a U-shaped valley carved through the pale leucogranites and gneisses of the Bernina massif. The valley walls above the glacier margins display the smooth, striated rock surfaces characteristic of recent ice contact, as well as prominent moraine ridges at various elevations that record the Little Ice Age maximum and successive retreat stages since then.
Retreat History: A Century of Records
Glaciological monitoring at Morteratsch began systematically in 1878 when the Swiss Glacier Monitoring Network (GLAMOS), one of the world's oldest glacier monitoring organisations, established annual terminus position measurements. The record shows that Morteratsch was close to its Little Ice Age maximum extent in the 1870s, with the terminus considerably further down the valley than today.
The twentieth century saw progressive retreat punctuated by two notable standstills and minor readvances. The glacier advanced slightly between approximately 1912 and 1920, and again during a series of cool, moist years in the mid-twentieth century. From the 1980s onward, retreat accelerated. The glacier has lost more than three kilometres of length since its maximum extent, and its area has decreased by roughly a third. Thinning of the ice surface has been documented using precision levelling surveys that show the upper glacier surface has lowered by tens of metres relative to early twentieth-century profiles.
The Marked Retreat Trail
The trail along the Morteratsch proglacial forefield is maintained in a way that makes the retreat history directly accessible to any walker. Wooden posts mark the position of the glacier terminus at ten-year intervals back to around 1900, and more recently at five-year intervals. Walking from the railway station to the current terminus, visitors pass these markers in sequence, the spacing between them indicating the speed of retreat in each period. Recent decades show larger spacings — faster retreat — than earlier ones.
The forefield between the marked terminus positions and the current ice is a landscape of raw glacial geology: polished and striated bedrock, lateral moraine ridges, ice-cored moraine hummocks, proglacial streams carrying milky meltwater, and ponds in recently deglaciated basins. Vegetation colonises the forefield progressively with distance from the current ice — bare rock and pioneer mosses immediately at the terminus, then herb communities, then developing shrub communities in the oldest-deglaciated areas near the trail head. The ecological succession of the forefield has itself been studied as a model system for understanding primary succession on recently deglaciated terrain.
Mass Balance and Scientific Monitoring
Morteratsch is one of the glaciers participating in the World Glacier Monitoring Service's global mass balance program, which coordinates annual net mass balance measurements at reference glaciers worldwide. Mass balance at Morteratsch is measured using a network of ablation stakes drilled into the ice across the glacier surface, supplemented by snow depth probing in the accumulation zone. Annual readings document the net gain or loss of ice mass each year, separating accumulation-season and ablation-season components.
Research groups from ETH Zurich and the University of Fribourg have used Morteratsch as a test case for glacier evolution models, calibrating ice flow and surface energy balance simulations against the long historical record. These models project continued retreat under all climate scenarios through the remainder of the twenty-first century, with the extent of eventual loss depending on the trajectory of global greenhouse gas emissions.
Nearby Glaciers and the Bernina Landscape
The wider Bernina area offers additional glacier destinations accessible from the same base at Pontresina or St. Moritz. The Diavolezza viewpoint above Pontresina, reached by cable car, provides a panoramic view of the Bernina glacier complex including Persgletscher and the ice fields below Piz Palü. A classic ski touring and summer ski route traverses the Persgletscher from the Diavolezza cable car station. The Bernina Pass at 2,328 metres, accessible by road and by the Rhaetian Railway Bernina line, separates the Engadin drainage from the Valtellina in Italy and provides views of hanging glaciers on the Bernina's south face.
The area around St. Moritz and the Upper Engadin valley has been a centre of Alpine tourism since the nineteenth century, with the Morteratsch Glacier among its most famous natural attractions. The combination of the scenic railway journey on the Bernina line, the glacier walk, and the mountain landscape of the Bernina massif makes this one of the most complete glacier experiences accessible in the Alps.
Locate Morteratsch Glacier in its Bernina Alps setting and explore other glaciated regions of the Eastern and Central Alps by using the map.