The melting ice from glaciers worldwide is leading to an increased loss of regional freshwater resources and causing global sea levels to rise at “ever-greater rates” by as much as 2cm over the course of this century alone, a decades-long study has revealed.

According to a new study led by researchers from the University of Edinburgh and the University of Zurich, glaciers have been losing 273 billion tonnes of ice each year for the last 25 years.

Separate from the continental ice sheets in Greenland and Antarctica, it was as recently as 2000 that glaciers once covered an area of 705,221 square kilometres and contained some 121,728 billion tonnes of ice globally. Since then, however, they have lost around 5% of their global ice cover.

On a regional scale, glaciers on the Antarctic and Subantarctic Islands have lost around 2% of their ice while those in Central Europe have witnessed a loss of 39%. Overall, glacier mass loss is about 18% larger than the loss of ice from the Greenland Ice Sheet and more than twice that from the Antarctic Ice Sheet.

As such, glaciers rank as the second-largest contributor to global sea level rise, following ocean warming. They are also natural indicators of climate change and play a vital role in many communities, providing vital water resources, especially during dry seasons.

“To put this in perspective, the 273 billion tonnes of ice lost in one single year amounts to what the entire global population consumes in 30 years, assuming three litres per person per day,” said Michael Zemp, a professor at the University of Zurich’s department of geography.

The study – Community estimate of global glacier mass changes from 2000 to 2023 – has been published this week in the scientific journal, Nature.

Led by an international team of scientists coordinated by the World Glacier Monitoring Service based in Zurich, the University of Edinburgh, and Earthwave, the study is part of a wider Glacier Mass Balance Intercomparison Exercise (known as GlaMBIE), taking data from a number of optical, radar, and laser satellite missions to produce an annual timeline of the world’s glaciers’ mass changes from the years 2000 to 2023.

Chief among the findings is that from 2000 to 2023, global glacier mass loss has totalled 6,542 billion tonnes. This loss has contributed nearly 2cm to global sea-level rise at an annual rate of 273 billion tonnes, or 0.75 millimetres each year. 

With this, glaciers are currently the second-largest contributor to global sea-level rise, after the warming of the ocean and before the contributions from the Greenland Ice Sheet, changes in land water storage, and the Antarctic Ice Sheet.

“When it comes to sea level rise, the Arctic and the Antarctic regions – with their much larger glacier areas – are the key players,” said Zurich University’s glaciologist, Inés Dussaillant. “Almost one quarter of the glacier contribution to sea-level rise originates from Alaska.”

The present study marks an important milestone for the International Year of Glaciers’ Preservation in 2025 and the Decade of Action for Cryospheric Sciences (2025 – 2034) declared by the United Nations. GlaMBIE is recognised as providing a new observational baseline for future studies, allowing improved projections of freshwater resources and sea-level rise.

“Our observations and recent modelling studies indicate that glacier mass loss will continue and possibly accelerate until the end of this century,” said GlaMBIE project manager, Samuel Nussbaumer.

“This underpins Intergovernmental Panel on Climate Change’s call for urgent and concrete actions to reduce greenhouse gas emissions and associated warming to limit the impact of glacier wastage on local geohazards, regional freshwater availability, and global sea-level rise.”

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