Current climate goals aren't enough to stop massive glacier losses

Earth’s glaciers are shrinking, and current climate pledges are not enough to stop this. A new international study warns that even if today’s promises hold, glaciers could lose 76% of their 2020 mass.

This extent of glacier loss would come with severe consequences – a 9-inch rise in sea levels, disrupted ecosystems, and an increase in the frequency of natural hazards.

The temperature rise associated with the current pledges could push global averages to as much as 4.9 degrees Fahrenheit (2.7 degrees Centigrade) above preindustrial levels.

Alaska, which is home to the third-largest glacier mass outside of Greenland and Antarctica, would lose 69% of its glaciers under these conditions.

The research comes from a team led by scientists from the University of Alaska Fairbanks Geophysical Institute and the University of Oslo.

Glaciers remember climate change

“This is the whole point: When you stop climate change, glaciers don’t stop losing mass,” said Professor Regine Hock, a co-author of the study.

“Glaciers have a memory. They continue losing mass for tens, hundreds, or even thousands of years until they retreat to high elevations where it’s colder.”

This study takes a new approach. Previous research typically stopped at the year 2100. But glaciers don’t follow calendars. Instead of an arbitrary end date, this study estimates how long it will take glaciers to reach equilibrium – the point at which gains from colder months balance losses from warmer months.

Scientists project that in Alaska, glaciers will reach this balance in about 330 years under the low-end Paris Agreement target of 2.7 degrees Fahrenheit (1.5 degrees Centigrade) warming.

Wordwide effort to understate glaciers

Hock emphasized the scale of the effort behind the research. “This is not a single study by one researcher; it’s an internationally coordinated effort. It was four years and brought together the entire community to work on global glacier modeling.”

The team included 21 scientists from 10 countries, using eight different glacier models. They focused on more than 200,000 glaciers, excluding the vast ice sheets of Greenland and Antarctica.

Scientists assumed constant temperatures for thousands of years in each scenario to give a clearer picture of the long-term future of glaciers.

How warming levels change the story

The researchers looked at various levels of warming. Even if temperatures stay at the current 2.1 degrees Fahrenheit (1.2 degrees Centigrade) above preindustrial levels, Alaska would still lose 37% of its glacier mass.

As average temperatures rise in the coming years, scientists expect Alaska’s glaciers to lose more mass, predicting that a 7.2-degree Fahrenheit (4-degree Centigrade) increase will cause an 80% loss in glacier mass.

For the planet as a whole, glacier mass losses are projected to reach 39% at the Paris Agreement’s lower average temperature increase target (2.7 degrees Fahrenheit or 1.5 degrees Centigrade). The predicted loss reaches a staggering 86% globally if the average temperature increase reaches 9 degrees Fahrenheit (5 degrees Centigrade).

Scientists associate current climate pledges – aiming to restrict average temperature rise to 4.9 degrees Fahrenheit (2.7 degrees Centigrade) – with a predicted 63% loss of glacier mass globally.

Why every degree counts

“Our study makes it painfully clear that every fraction of a degree matters,” said Harry Zekollari from Vrije Universiteit Brussel in Belgium. “The choices we make today will resonate for centuries, determining how much of our glaciers can be preserved.”

Lilian Schuster from the University of Innsbruck noted that glaciers are good indicators of climate change because their retreat allows us to see with our own eyes how climate is changing.

“However, since they adjust over longer timescales, their current size vastly understates the magnitude of climate change that has already happened. The situation for glaciers is actually far worse than visible in the mountains today,” said Schuster.

Action needed to save glaciers

The research highlights that glaciers are slow to respond to change, but once triggered, the losses are difficult to stop. Even ambitious efforts to limit warming won’t halt glacier retreat entirely – but they can slow it down.

If nations strengthen their climate commitments, they can limit glacier loss and mitigate the worst impacts on sea level rise and biodiversity. The choice is clear: reduce emissions now, or face centuries of rising seas and shrinking ice.

The full study was published in the journal Science.

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