A new international study has delivered a sobering message: once Earth warms beyond the critical 1.5°C limit, even temporarily, many of the world’s glaciers could be damaged beyond repair for centuries.
Even if we manage to cool the planet back down later, the ice won’t come back quickly—if at all.
The research, led by scientists from the University of Bristol and the University of Innsbruck, is the first to simulate how mountain glaciers around the world might change between now and the year 2500 in so-called “overshoot” scenarios.
These are situations where the Earth heats up past the 1.5°C Paris Agreement target—possibly reaching up to 3°C—before eventually cooling back down through future technologies and emissions cuts.
Published in Nature Climate Change, the study shows that temporary overshoots have lasting impacts.
Glaciers in an overshoot scenario could lose up to 16% more of their mass than in a world where temperatures never cross the 1.5°C threshold.
This loss contributes significantly to rising sea levels and disrupts freshwater sources for millions of people.
Dr. Fabien Maussion, a climate expert from the University of Bristol, explained that current climate policies are pushing us toward a future with about 3°C of warming.
“We wanted to know if glaciers can recover once the planet cools again,” he said. “Unfortunately, our findings suggest that they won’t—at least not in our lifetimes, or even our children’s.”
The research team modeled a scenario where temperatures rise steadily to 3°C by 2150, then gradually fall back to 1.5°C by 2300, a path that assumes delayed climate action and heavy reliance on future carbon removal technology.
Even under this optimistic reversal, the damage is significant. Compared to a scenario where the 1.5°C target is never exceeded, glaciers would still lose 11% more mass by 2500.
Dr. Lilian Schuster from the University of Innsbruck, lead author of the study, said that while large polar glaciers might take millennia to recover, smaller mountain glaciers—in places like the Alps, Himalayas, and Andes—might not begin regrowing until around the year 2500.
This loss affects more than just sea levels. Glaciers serve as crucial water sources for communities downstream, especially during dry seasons. As glaciers shrink, they release more meltwater temporarily—known as “peak water.” But when they begin to regrow, they store water as ice again, leading to reduced flows, or “trough water,” which could strain future water supplies.
The researchers warn that overshooting climate targets locks in long-term damage. “The longer we delay cutting emissions,” said Dr. Maussion, “the more we commit future generations to irreversible changes.”
Source: University of Bristol.
