From 2000 to 2023, the global glacier mass loss totals 6,542 billion tonnes – or 273 billion tonnes of ice lost per year
The year 2024 was declared the hottest ever. There are consequences to that like life-threatening heatwaves, and rapid melting of glaciers. In fact, it turns out that glacier melt is the second-largest contributor to sea-level rise now, after global warming, according to a study published in Nature.
Five of the past six years have seen the most rapid glacier retreat on record, and most glaciers across the world will absolutely melt before 2100. This puts at risk freshwater supply for potentially billions of people across the world.
The most troubling effect of melting glaciers will be faced by people residing in mountains, which are key water banks, storing 68.7% of the earth’s freshwater supply.
The mountains are home to around 1.1. billion people, or 14% of the world’s population, according to The United Nations World Water Development Report 2025. Between 1975 and 2015, the population in 35% of mountain subregions doubled, while the proportion of urban residents within these mountain areas increased from 6% to 39% over the same period.
Risky meltdown
“WMO’s State of the Global Climate 2024 report confirmed that from 2022-2024, we saw the largest three-year loss of glaciers on record. Seven of the 10 most negative mass balance years have occurred since 2016,” said Celeste Saulo, the Secretary-General of the World Meteorological Organization.
There are more than 275,000 glaciers worldwide, which cover approximately 700,000 sq km. Together with ice sheets, glaciers store about 70% of the global freshwater resources.
As more and more glaciers melt, the freshwater supply of people in river-fed regions are threatened. This water is especially critical during summers and dry periods of the year. Also, due to rapid melting, more water flows in a short time period, increasing the chances of flooding.
Based on a compilation of worldwide observations, the World Glacier Monitoring Service estimates that glaciers (separate from the continental ice sheets in Greenland and Antarctica) have lost a total of more than 9,000 billion tonnes since records began in 1975. “This is equivalent to a huge ice block the size of Germany with a thickness of 25 metres,” says Dr. Michael Zemp, the Director of the WGMS.
Glacier mass refers to the net change in a glacier’s mass over a period, determined by the difference between accumulation through snowfall and ice formation, and melting. From 2000 to 2023, the global glacier mass loss totals 6,542 billion tonnes – or 273 billion tonnes of ice lost per year, according to the Nature study.
This amounts to what the entire global population currently consumes in 30 years, assuming three litres per person per day. During this period, glacier melt contributed 18 mm to global sea-level rise. “This might not sound much, but it has a big impact: every millimetre sea-level rise exposes an additional 200,000 to 300,000 people to annual flooding,” said Zemp.
The year 2024 was the third year in a row where all 19 glacier regions experienced a net mass loss, amounting to a total loss of 450 billion tonnes.
“Preservation of glaciers is not just an environmental, economic and societal necessity. It’s a matter of survival,” said WMO’s Paulo.
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