This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: On June 29, 2026, the snow accumulated by Switzerland's glaciers over the course of the previous winter had melted. Known as Glacier Loss Day, this date marks the point at which further melting begins to erode the glaciers' mass until snow accumulation resumes in the fall.
Matthias Huss, the network head of Glacier Monitoring in Switzerland (GLAMOS), told (AFP) that this year's Glacier Loss Day was "three months too early, compared to a healthy state." Modeled on Earth Overshoot Day, Glacier Loss Day serves as both a benchmark of glaciers' health and an indicator of broader annual warming trends across the Alps. This year's Glacier Loss Day was the second-earliest on record, falling only three days later than it did in 2022—a year in which glaciers lost about 6% of their mass overall. Experts suggest that this year's early, rapid melt is largely the result of two consecutive European heat waves in June and July, which pushed temperatures above 40°C (104°F) in parts of central Europe.
The daytime freezing level in parts of the Alps rose to 4,500 meters (14,800 feet) in June, and even at high altitudes there was little overnight refreezing, leading to risks such as a higher likelihood of avalanches and slope instability. In the Mont Blanc massif in the French Alps, aerial imagery shows that the Bossons Glacier, which looms above the resort town of Chamonix, is experiencing extensive glacial melt. In areas where the glacier's ice touched the valley floor in the 1980s, meltwater streams are now visible flowing down the rock alongside the receding glacier.
Moreover, a large hole first spotted in the lower tongue of the glacier in 2025 remains visible more than a year after it was identified. This could reflect the significant reduction in snowfall compared with the 2010–2020 average: Snow depths in the central European alpine region during the 2025–26 winter season were among the five lowest seen in the last three decades. With less snow to reflect sunlight, more of the glacier's darker, older ice is exposed.
That ice absorbs more sunlight than snow because of its lower albedo, so its exposure accelerates overall glacial melt. The Rhône Glacier, located in the southern Swiss Alps, lost more than 4 meters (13 feet) of ice thickness in June and July of this year. As of July 2026, GLAMOS reports the glacier is losing an average of 10 centimeters of ice per day.
As meltwater widens cracks and hollows into cavities, more are expected to appear near the glacier's lower zone, as at Bossons. The consequences extend beyond the glacier itself: The Rhône Glacier's meltwater feeds the Rhône River, which runs for more than 500 miles (800 kilometers) through Switzerland and France. Roughly 2.5 million people rely on the Rhône for drinking water, with millions more dependent on the agriculture it supports.
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