Daily weather data point to faster glacier loss

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 thus 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 study finds, glacier models can better capture 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 higher-resolution model better reproduces observed glacier mass loss, particularly during exceptional melt years such as 2022 and 2026 in the European Alps, 2023 in Western North America, 2024 in Svalbard, and 2025 in Central Asia.