Swiss Alps Jungfrau-Aletsch

Bernese Alps, Switzerland · Last Ice Age to Present · UNESCO 2001 Risk Level: Vulnerable

Site at a Glance

Location: Bernese Alps, Valais and Bern cantons, Switzerland Coordinates: 46.4333° N, 8.1167° E Type: Natural Heritage Sub-types: Glacial Landscape, Alpine Ecosystem, Climate Reference Site Period: Glacial landscape from last Ice Age; Aletsch Glacier in current form approximately 10,000 years; UNESCO inscribed 2001, extended 2007 Risk Level: Vulnerable UNESCO Status: Inscribed 2001

3D Documentation

The Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) and the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at ETH Zurich maintain high-resolution terrain models and ice thickness data for the Aletsch Glacier, available through the Swiss Glacier Monitoring Network at glamos.ch. Swisstopo, the Swiss federal mapping agency, provides 3D terrain data across the entire Swiss Alps at swisstopo.admin.ch. A digital terrain model of the Jungfrau region is available on Sketchfab.

• Swiss Glacier Monitoring Network: https://www.glamos.ch/
• Swisstopo 3D terrain data: https://www.swisstopo.admin.ch/
• UNESCO dossier: https://whc.unesco.org/en/list/1037

Site Description

The Aletsch Glacier is 23 kilometres long and, at its deepest point, approximately 900 metres thick. It contains enough ice — approximately 27 cubic kilometres — to bury all of Switzerland under a metre of water. It descends from a gathering ground near the Jungfrau, Mönch, and Aletschhorn peaks through increasingly narrow valleys before terminating above the Rhône valley, where its meltwater eventually feeds the river that flows through France and into the Mediterranean.

The glacier moves. It flows downslope at approximately 200 metres per year at its centre, dragging rock debris scraped from the valley walls as lateral and medial moraines — dark lines of rubble running parallel to the glacier's axis that make its movement visible. Trees that have been dead and preserved in the glacier for centuries occasionally emerge from the terminal area as the ice melts, providing radiocarbon dating evidence for past glacier extents.

The surrounding landscape is Alpine in the full sense: rock faces above the glacier that rise vertically for hundreds of metres, populated by ibex, chamois, and golden eagles; forests of stone pine and larch at the glacier margins that have been classified as among the oldest in the Alps; wildflower meadows at lower elevations that support botanical diversity unusual for their latitude.

Historical Significance

The Aletsch Glacier entered scientific consciousness in the mid-19th century when the physician and naturalist Louis Agassiz used it as the primary field site for his glacial theory: the controversial and ultimately correct argument that ice ages had shaped the landscape of the Northern Hemisphere. Agassiz spent several seasons on the glacier in the 1840s, living in a boulder crevice he called the Hotel des Neuchâtelois, making measurements that would eventually overturn existing geological theory. The glacier is therefore not only a natural heritage site but a site in the history of science.

The Eiger's north face, the Nordwand, is the most culturally resonant mountaineering wall in the world. First climbed in 1938 after multiple fatal attempts that generated obsessive coverage in European newspapers, it became the defining test of a generation of alpinists and produced a cultural literature about risk, ambition, and mortality that extended well beyond the climbing community. Heinrich Harrer, one of the four climbers who made the first ascent, subsequently crossed Tibet and wrote Seven Years in Tibet. The Eiger became a symbol of human ambition against indifferent nature that European culture absorbed in the post-war period with a particular intensity.

The Story

c. 10,000 BCE — Glacier Formation As the last Ice Age draws to a close, the Aletsch Glacier takes its current form in the valleys of the Bernese Alps. The glacial landscape — U-shaped valleys, hanging valleys, arêtes, and cirques — is scoured into its current configuration.

1840s — Agassiz and the Ice Age Theory Louis Agassiz uses the Aletsch Glacier as his primary field site for developing the glacial theory, spending seasons making measurements on the ice. His work revolutionises the understanding of Earth's climatic history.

1858 — First Systematic Measurements The first systematic measurements of the Aletsch Glacier's length and movement begin, establishing the baseline against which subsequent retreat can be measured. The glacier at this time extends approximately 3 kilometres further than its current terminus.

1938 — First Ascent of the Eiger Nordwand Heinrich Harrer, Fritz Kasparek, Andreas Heckmair, and Ludwig Vörg complete the first ascent of the Eiger's north face after a four-day climb. The ascent becomes one of the defining moments of 20th-century alpinism.

2001 — UNESCO Inscription The Jungfrau-Aletsch-Bietschhorn area is inscribed on UNESCO's World Heritage List. The inscribed area is extended in 2007.

2022 — Accelerating Retreat Swiss glacier monitoring records the fastest rate of glacier retreat in the measurement period. The Aletsch Glacier loses 4 kilometres of length between 1870 and 2022, with the rate of loss accelerating significantly after 2000.

Threats and Risk Assessment

Glacier Retreat The Aletsch Glacier is retreating at an accelerating rate. It currently loses approximately 50 metres of length and 60 million cubic metres of volume annually. Under current climate projections, the glacier will lose 90 percent of its volume by 2100. What remains will be a much smaller ice body confined to the highest cirques, no longer connected in a continuous glacier system. The process is not a future risk. It is a present reality, measurable year by year.

Permafrost Thaw Rising temperatures are thawing the permafrost that binds mountain rock faces together. The frequency and scale of rockfalls in the Alps has increased measurably since the 1990s. Entire ridge systems whose stability depended on ice-cemented joints are becoming geologically active as the cement thaws. Some popular climbing routes have become significantly more dangerous due to rockfall, and several villages below known rock faces are operating under avalanche and rockfall risk protocols that did not exist a generation ago.

Freshwater Consequences The Aletsch Glacier is a freshwater reserve. Its meltwater feeds the Rhône and contributes to the water supply of Switzerland, France, and countries downstream. As the glacier retreats, meltwater volumes will initially increase as stored ice melts, then decline sharply as the ice body is depleted. The downstream consequences for agriculture, hydropower, and municipal water supply in the Rhône basin have been modelled and are severe.

Research and Scholarly Context

The Swiss Alps host some of the world's most intensive glaciological monitoring. The Swiss Glacier Monitoring Network (GLAMOS) maintains continuous measurements of glacier length, mass balance, and terminus position for over 100 glaciers, with the Aletsch Glacier as the flagship site. ETH Zurich's VAW produces annual glacier reports that are internationally cited as primary data sources for global glacier retreat documentation. The Paul Scherrer Institute and WSL contribute interdisciplinary research on climate-glacier interaction. The Visual History of Aletsch project, curating historical photographs against current images, provides some of the most compelling public documentation of glacier change available anywhere.

If Nothing Changes

By 2100, the projections suggest that 90 percent of the Aletsch Glacier will be gone. That is not a metaphor or a worst-case scenario. It is the central estimate of the best available scientific modelling given current emissions trajectories. The glacier that Agassiz stood on in the 1840s, that the first alpinists used as their staging ground for the peaks above it, that UNESCO inscribed in 2001, will be a fraction of its current size within the lifetimes of people already alive. The World Heritage Site designation will remain. The landscape of peaks and valleys will remain. The glacier that defines the site, that is the reason for the inscription, will largely not. This is not a conservation failure in the conventional sense. No amount of visitor management or site protection can halt the climate mechanism that is removing the ice. The Aletsch Glacier's future is being determined not at the glacier but in the decisions about fossil fuel emissions being made in parliaments and boardrooms around the world.