Mont Blanc is retreating and Swiss glaciers have lost almost 30% of their volume in a decade

Global warming is accelerating glacier retreat and altering the water cycle across the continents (REUTERS/Denis Balibouse)Global warming is altering the water cycle and transforming landscapes that for centuries seemed stable. Rising temperatures are accelerating glacier retreat, reducing snow cover in the mountains, and weakening ice masses in polar regions. These changes affect freshwater reserves, alter river flows, and increase the risks of avalanches, landslides, and floods in mountain areas. Melting ice also has consequences far from the peaks. Water from glaciers and ice sheets adds to the oceans, which also expand as they warm. Sea level is encroaching on coastlines, worsening flooding during storms, and promoting saltwater intrusion into aquifers, crops, and supply systems. Coastal communities, small island states, and large cities located in low-lying areas are exposed to a problem that combines loss of territory, damage to infrastructure, and pressure on water resources. In mountain ranges, variations in snow and ice offer a visible signal of a global-scale process. Not all respond at the same speed, nor does each annual change by itself explain the climate trend, but the sustained retreat of glaciers and the decline of snow in numerous regions show how rising temperatures modify both the heights and the water available on the continents, France 24 reports. The 2026 measurement placed the altitude of Mont Blanc at 4,807 meters according to the accumulated snow layer (REUTERS/Gonzalo Fuentes)The latest measurement placed Mont Blanc at 4,807 meters, 1.88 meters above the figure released in 2023. The data might suggest a recovery, but comparison with a longer series shows a different trajectory: the mountain stood 1.29 meters below the height reported in 2025 and 3.43 meters below its recent maximum of 4,810.90 meters, measured in 2007. The 2026 figure does not mean the mountain has grown in a geological sense. Also known as the "Roof of Europe," it sits at about 4,792 meters above sea level; what varies is the layer of snow and ice covering it. Its volume and shape depend on precipitation, wind, temperature, solar radiation, and the weather conditions of the months preceding each expedition. Surveyors used ground-penetrating radar and drones to assess the ice and rock structure of Mont Blanc (REUTERS/Denis Balibouse)"The summit is in constant motion," said Jean des Garets, president of the Departmental Chamber of Expert Surveyors of Haute-Savoie, during the presentation of the new data, as reported by France 24. The specialists have been conducting these campaigns since 2001 and warn that variations of several meters between one measurement and another are part of the dynamics of that snow and ice cover. Even with those fluctuations, the long-term reference points to a decline. Des Garets told Franceinfo that the average of the measurements taken over 25 years is around 4,808.80 meters. "We were always above during the first 13 years and, since then, always below," he noted. The series of records from the last 25 years reflects a downward trend in the height of Mont Blanc (REUTERS/Denis Balibouse)The behavior of the summit must be interpreted with caution in light of global warming. A single measurement cannot determine how much climate change contributed, because a season with more snow or less intense winds can temporarily raise the surface layer. "Each isolated measurement is not significant in itself" in that context, Des Garets argued, though he added that the records allow scientists to build a series they can analyze over time. The surveyors measured the summit on September 17 with satellite positioning systems, drones, and, for the first time, a ground-penetrating radar capable of examining the thickness of the ice and rock beneath the surface. That technology seeks to separate fluctuations in the seasonal cover from changes that may affect the structure of the mountain. The so-called "Roof of Europe" remains at a height below usual levels (REUTERS/Denis Balibouse)The trend of the summit coexists with a broader deterioration of Alpine glaciers. The 2026 increase does not contradict that process: it reflects the variability of a layer exposed to each year's weather. The sequence of measurements, on the other hand, makes it possible to observe that the highest point in Western Europe remains below the levels that exceeded 4,810 meters at the beginning of this century. The glaciers of the Alps are going through another year of accelerated losses. In Switzerland, where the largest glacial area of the range is concentrated, the ice lost 5.5% of its volume in 2026, according to the Glacier Monitoring Switzerland network (GLAMOS) and the Swiss Academy of Sciences. It was the second-largest annual decline since records began, behind only 2022. Switzerland's glaciers lost 5.5 percent of their volume in 2026 according to GLAMOS (AP Photo/Matthias Schrader, File)The figure takes on another dimension when recent evolution is considered: Swiss glaciers lost nearly a fifth of their volume in the last five years. Between 2016 and 2026, the cumulative reduction reached 27%, according to GLAMOS balances. The decline was due to a winter with little snowfall and a succession of heat waves between May and September, which left the ice exposed earlier than usual. Snow serves a protective function because it reflects part of the solar radiation and delays melting. In 2026, that cover disappeared in some sectors before the end of June. The freezing level exceeded 4,000 meters for 76 days, more than double the average, while by the end of summer there was no snow left even at 3,500 meters of altitude, according to data collected by the BBC. Heat waves between May and September left the ice mass exposed early in the Alps (EFE/EPA/JEAN-CHRISTOPHE BOTT) The consequences were seen in the thickness of the ice masses. Some glaciers lost between 2.5 and 4 meters of average thickness; in the most exposed glacier tongues, the reduction reached 10 meters. The Aletsch glacier, the largest in the Alps, recorded a loss of 13 meters of ice at one of its lowest monitoring points, Swissinfo reported."Alpine glaciers have no chance of surviving in the long term under these conditions," warned Matthias Huss, director of GLAMOS. The warming does not affect Switzerland alone: in Austria, teams from the Austrian Alpine Club also reported significant losses in length and mass, with signs of exceptional retreat in the Pasterze glacier, at the foot of the Grossglockner.