Between 2000 and 2023, glaciers lost an estimated 273 billion tonnes of ice annually, making them the second-largest contributor to rising sea levels, according to a new study published in Nature. The total global ice loss during this period reached 6.54 trillion tonnes, raising sea levels by 18 millimeters (mm) and contributing 0.75 mm of sea-level rise per year.
The study revealed that ice loss accelerated by 36% in the second half of the study period (2012-2023) compared to the first half. Recent years saw the most severe losses, with the 2019-2023 period witnessing annual ice loss exceeding 400 gigatonnes per year (Gt/yr), including a record 548 Gt/yr in 2023.
“This underscores the Intergovernmental Panel on Climate Change’s call for urgent action to cut greenhouse gas emissions to limit the impact of glacier wastage,” said lead author Samuel Nussbaumer, a glaciologist at the University of Zurich (UZH).
The largest regional contributors to glacier mass loss were Alaska (22%), the Canadian Arctic (20%), peripheral glaciers in Greenland (13%), and the Southern Andes (10%). Smaller glaciers, covering less than 15,000 square kilometers, saw the most significant relative ice loss.
Glacier loss also outpaced ice sheet losses, with glaciers melting 18% more than Greenland’s ice sheet and twice as much as Antarctica’s. The melting glaciers contributed 20% of the observed global sea-level rise between 2003 and 2016, second only to ocean warming (33%).
The study highlighted the critical role glaciers play in freshwater availability for regions like Central Asia and the Central Andes, where glacier melt sustains rivers during warm, dry seasons. However, in terms of sea-level rise, the Arctic and Antarctic regions are the primary drivers due to their vast glacier areas.
“Almost one quarter of the glacier contribution to sea-level rise comes from Alaska alone,” said UZH glaciologist Inés Dussaillant, who participated in the Glacier Mass Balance Intercomparison Exercise (GlaMBIE) that mapped global glacier changes for the next IPCC report.
Researchers emphasized the importance of continued monitoring and international cooperation to reduce emissions and mitigate glacier loss, which will be a key driver of sea-level rise in the coming decades.