A new study led by researchers at ETH Zurich (Switzerland) and the Vrije Universiteit Brussel (Belgium) reveals that glaciers worldwide could lose ice faster than previously projected. Published today in Nature Communications, the research shows that accounting for daily weather variability leads to more realistic simulations of glacier melt and results in greater projected ice loss by the end of the century. The findings highlight the importance of short-lived weather events, such as the exceptional heatwaves and extreme melt seasons recently observed in several glacierised regions around the Globe.
Why daily weather matters
Most global glacier models rely on monthly climate data, which smooth out short-term weather fluctuations. Yet glaciers respond rapidly to individual weather events, including heatwaves, heavy precipitation and sudden temperature changes. A few exceptionally warm days can rapidly remove protective snow cover, exposing darker glacier ice that absorbs more sunlight and melts faster. Similarly, whether heavy precipitation falls as rain or snow can strongly influence glacier accumulation and runoff, particularly when temperatures fluctuate around the freezing point. By resolving these processes day by day, the model better captures rapid transitions between snow-covered and exposed ice surfaces, as well as the associated changes in melting.
"Glaciers don't respond to monthly averages, but to the weather they experience every single day," explains lead author Lander Van Tricht (ETH Zurich / WSL / Vrije Universiteit Brussel). "A heatwave lasting only a few days can cause enormous amounts of ice to melt. By averaging weather conditions over an entire month, we risk underestimating the impact of these extreme events."
To better capture these processes, the researchers extended the Global Glacier Evolution Model (GloGEM) to operate at daily resolution, applying it to more than 12,500 glaciers representing 94% of the world's glacier ice volume. Compared with the traditional monthly approach, the enhanced model better reproduces observed glacier mass loss, particularly during exceptional melt years such as 2022 in the European Alps, 2023 in Western North America, 2024 in Svalbard, 2025 in Central Asia and 2026 again in the European Alps.
Extreme melt years could shape the future of glaciers
The study shows that the effects of daily weather variability accumulate over time. When projected into the future, the daily model generally predicts faster glacier retreat and greater ice loss than its monthly counterpart, particularly in regions where melting is strongly influenced by short-term temperature fluctuations. This also translates into a larger projected contribution to global sea-level rise. The daily model used in this study projects a 5-10% higher 21st century contribution from glaciers to sea-level rise than its monthly counterpart.
"Our findings suggest that existing global projections, which typically rely on monthly climate forcing, may underestimate how quickly glaciers will lose ice in a warming world," says Van Tricht. "It is not only the gradual rise in temperature that matters. Extreme melt events, like those we have recently witnessed in the European Alps and other regions, can have lasting consequences for glaciers. Capturing these events is therefore essential to better understand their future."
Beyond glacier retreat and sea-level rise, the study also reveals important changes in the timing and intensity of glacier meltwater runoff, with implications for downstream water resources.
"Glaciers are an important source of freshwater for millions of people," explains Harry Zekollari (Vrije Universiteit Brussel) who co-supervised the study. "Understanding not only how much ice will disappear, but also when meltwater becomes available, is crucial for anticipating future changes in water availability. Our study shows that resolving daily weather variability can substantially improve our understanding of these changes."
Reference
Van Tricht, L., Huss, M., Zekollari, H., et al. (2026). Resolving short-term meteorological variability amplifies projected glacier loss and sea-level rise. Nature Communications. DOI: 10.1038/s41467-026-78260-y
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