Computer models that forecast the world's glaciers may be underestimating how much ice they will lose, because most of them miss short heat waves, according to Earth.com, which reported on a new study in the journal Nature Communications.

Most glacier models run on monthly average temperatures, so a few very hot days get blended into cooler ones, the site reported. A team from ETH Zurich and the Vrije Universiteit Brussel rebuilt one model, called GloGEM, to run day by day.

Across 12,571 glaciers that hold 94% of the world's glacier ice, the daily version projected 5% to 10% more ice loss by 2100 than the monthly one. That works out to an extra 20 to 33 millimeters, or 0.8 to 1.3 inches, of sea level rise, according to Earth.com.

"A heatwave lasting only a few days can cause enormous amounts of ice to melt," said lead author Lander Van Tricht. A run of warm days can strip away snow and expose darker ice, which soaks up sunlight and melts faster, the site explained.

The daily model matched field measurements better in extreme melt years, such as the Alps' record melt in 2022. The biggest differences were in Svalbard and the Russian Arctic, where it projected up to 25% more loss. The authors call those upper-end estimates. Iceland was the one place it projected less loss.

Glaciers outside the big ice sheets lost about 273 billion metric tons of ice a year from 2000 to 2023, Earth.com reported. Glaciers supply fresh water to nearly 10% of the world's people. Van Tricht said each extra millimeter of sea level rise could expose another 200,000 to 300,000 people to yearly flooding.

The model leaves out glaciers smaller than about 5 square kilometers, and daily runs take about 10 times the computing power.

What we know: Running a glacier model day by day raised projected ice loss by 5% to 10% by 2100.
What we don't: Whether other models will confirm it. Only Earth.com has reported this so far; NewsHabit hasn't seen independent confirmation.