Even though humans have managed to reverse global warming, the world’s mountain glaciers have prospects for centuries even though they have managed to reverse global warming, according to a groundbreaking new study. Researchers found that once glaciers start to disappear, they cannot be easily restored even if temperatures return to safer levels, allowing our descendants to inherit a permanent climate legacy long after we disappear.
The study, published today in Natural Climate Change, presents the first global forecast for glacier changes to 2500 years, providing an unprecedented long-term view on how these key ice formations respond to climate “outdated”, where global temperatures temporarily exceed the 1.5°C Paris Agreement before cooling down.
If the planet warms it to 3°C before subsequently cooling to 1.5°C, the glacier will lose up to 16% of its mass compared to the case where the temperature never exceeds the 1.5°C target. This additional melt will make a significant contribution to sea level rise and destruction of water supply in vulnerable areas.
Long shadows of temporary warming
“Current climate policies place the earth on a path close to 3°C. It’s clear that for glaciers, this world is much worse than glaciers holding a 1.5°C limit,” said Dr. Fabien Maussion, associate professor of polar environmental change at the University of Bristol.
The question of whether glaciers can be restored after they are outdated has had a significant impact on future generations. Unfortunately, the answer seems frustrating.
“Our purpose is to discover whether glaciers can be recovered if the earth cools again. This is a question raised by many – will glaciers regenerate in our lives or our children’s glaciers? Our findings suggest that it is impossible to show regrettably,” Maussion added.
The study is because the Earth experienced its hottest year in 2024, with global temperature temporarily exceeding the 1.5°C threshold for the first time throughout the calendar year.
Not all glaciers react
The study found that different glaciers respond to warming and cooling at different rates, some of which may recover faster than others. Researchers identified key patterns of how glaciers around the world act in outdated programs:
- Large polar glaciers will take hundreds of years, if not thousands, to recover from 3°C overshoot
- Smaller mountainous glaciers in areas such as the Alps, Himalayas and Tropical Andes may recover by 2500 years – but not within the lifetime of the next few generations
- Even if the temperature returns to 1.5°C, the glacier will still reduce the mass by 2500, and the temperature never exceeds this threshold.
- Additional melt from obsolete will lead to greater sea level rise, affecting coastal communities around the world
“Trough Water”: New Climate Challenge
The study introduces a novel concept called “trough water” that describes what happens when a glacier begins to regenerate after it expires. When glaciers expand, they store water again as ice, reducing downstream flow, contrary to the well-documented “peak water” phenomenon, which occurs during the initial glacier melting.
“If glaciers grow again, they start storing water again, which means we call it downstream water flow compared to peak water. We call this effect ‘trough water’.” “We found that about half of the basins we studied will experience some form of trough water of more than 2,100.”
This can present unexpected challenges to water management in glacier feeding areas, especially during dry seasons when meltwater is critical to agriculture, hydropower and drinking water supply.
What makes these findings particularly sober? After peak warming, water flows decreased over the decades to centuries, and even if the temperatures dropped to safer levels, the water flows decreased over the decades.
Tick clock
To conduct the study, the researchers used open source open source glacier models developed at the University of Bristol and partner institutions, coupled with climate predictions from the University of Bern, Switzerland. Their simulations go far beyond typical climate predictions and usually end around 2100.
The study considered a scenario where the global temperature rose to around 2150 to around 3.0°C, then dropped to 1.5°C 2300, and then stabilized. The road represents the future of human delaying severe climate action, but ultimately deployed negative emission technologies such as carbon capture to reduce temperatures.
“Over 1.5°C, even temporarily locking out glacier losses for centuries,” Mocio warned. “Our research shows that even if temperatures later return to safer levels, most of these damages cannot be simply removed. The longer we delay reducing emissions, the more burdens our offspring, the more irreversible changes.”
As world leaders debate the pace of climate action and the feasibility of staying below the 1.5°C threshold, the study provides compelling evidence that temporary overconflict has permanent consequences. Even if we eventually cool the Earth with technical interventions, our ancestors’ glaciers respect and depend on the scars we have decided over the centuries.
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