Many glaciers in western Canada, the United States, Scandinavia, Central Europe, the Caucasus, New Zealand and the tropics will not survive the 21st century – and this will have a “dramatic impact” on mountain communities and hundreds of millions of people who depend on water that originates from these glaciers.

These are the key findings of the latest reports from the United Nations (UN) agency World Meteorological Organization (WMO), and the Zurich-based glacier monitoring agency World Glacier Monitoring Service (WGMS).

Glaciers are among the key indicators of the health of our planet, and some of the world’s largest rivers including the Ganga, Brahmaputra, Indus, and Yangtze, originate from the glaciers.

But those glaciers are now rapidly retreating.

“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 ten most negative mass balance years have occurred since 2016,” said WMO Secretary-General Celeste Saulo.

“Preservation of glaciers is a not just an environmental, economic and societal necessity. It’s a matter of survival.”

Since 1975, the world’s glaciers have lost 9,000 billion tonnes of ice or an ice block the size of Germany, with a thickness of 25 meters. This has pushed the sea levels up by 25 mm.

See related story: The Year 2024 Was Warmest-Ever on Record – Temperature Rise Likely Exceeded 1.5°C

Melting glaciers are putting food security at risk

The 2024 data shows that, for the third consecutive year, all the glaciers around the world had lost mass.

The rate of melting of glaciers is directly linked to the rising global temperatures, Stefan Uhlenbrock, Director of Water and Cryosphere department at the WMO said.

As 2024 was the warmest year on record, temperatures are expected to continue to rise, and Uhlenbrock warned the changes this will cause will be dramatic.

“Globally, in the interconnected economy, it’s everyone around the world who’s indirectly impacted from these dramatic changes. It’s putting at risk the water supplies. It’s putting at risk food security, energy security, as well as the ecosystem services that water resources and other resources provide. But you shouldn’t also forget the social, the cultural as well as the spiritual values glaciers have,” he said during a press conference.

The reports were released to mark the first World Day for Glaciers on March 21 this year, and sound alarm that the accelerating glacier melt risks unleashing cascading impacts on economies, ecosystems and communities.

Source of 70% of world’s freshwater under threat

There are approximately 275,000 glaciers around the world that cover roughly 700,000 km² or the equivalent of twice the size of Germany. These exclude the continental-sized ice sheets of Greenland and Antarctica.

The glaciers are in high mountain regions often referred to as the world’s water towers as glaciers are the source of about 70% of the world’s freshwater reserves.

In the short-term, increased glacier melting increases the risk of natural hazards such as floods for those living downstream. But in the long-term, they threaten the water security of people as the rivers that the glaciers feed risk running dry. In dry and hot seasons in some areas, glacier runoff is often the only water available.

“Hotspots of water availability from glaciers are Central Asia and the central Andes, where glaciers in the hottest and driest months are often the only water resource,” Dr Michael Zemp, Director of the WGMS said during the press conference. WGMS has been coordinating glacier monitoring for over 130 years now.

Glacier melt contributes to sea-level rise

The new findings complement a recent study published in the journal Nature in February, which found that between 2000 and 2023, glaciers lost 5% of their remaining ice.

From 2000 to 2023 alone, the global glacier mass loss totals 273 billion tonnes of ice every year, according to the reports. This amounts to 6,552 billion tonnes over 24 years or what the entire global population currently consumes in 30 years (assuming three litres per person per day).

Regionally, the loss of glacier ice ranges from 2% in the Antarctic and subantarctic islands to almost 40% in Central Europe.
This melting ice is currently the second-largest contributor to global sea-level rise, after the warming of the ocean.

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 millimeter sea-level rise exposes an additional 200,000 to 300,000 people to annual flooding,” says Zemp.

Based on a compilation of worldwide observations, the WGMS 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.

“If you take the example of Germany, it would be an ice block of the size of Germany, with a thickness of 25 meters. That is the ice that we lost since 1975 from glaciers,” Zemp said. “This is about 25 millimetres of sea level rise, or currently, a bit more than one millimetre each year,” he said.

The Greenland ice sheet is also melting while the Antarctic ice sheet is not contributing “so much” to the rising water levels at the moment. But as the temperatures continue to rise that will change.

“For the next decades, the glaciers are the drivers for the sea level rise. When we talk about the next centuries, it’s the ice sheets that we have to worry about,” Zemp said.

Preservation of glaciers is a necessity

The 2024 hydrological year, calculated from 1 October 2023 to 30 September 2024, saw the fourth-highest glacier mass loss on record. It was also the third year in a row during which all 19 glacier regions in the world experienced a net mass loss.

This loss was relatively moderate in regions like the Canadian Arctic and the Greenland periphery but glaciers in Scandinavia, Svalbard (Norwegian archipelago) and North Asia experienced their largest annual mass loss on record.

“I just want to want to stress that preserving glaciers is not only an environmental imperative, it’s really a survival strategy,” said WMO’s Uhlenbrock.

He pointed to the 2022 heatwave in Europe when the heat caused the Swiss Alps to lose 10% of its ice in two years.

“This was also the year when it was so hot that several nuclear power plants in France had to be shut down because of the lack of cooling water. It was such a dry and hot time that there were energy supply problems,” he said.

“We need to advance through better observation systems, through better forecasts and better early-warning systems for the planet and the people. Only then we can protect our water supplies, the livelihoods of people, as well as ecosystems for future generation,” he said.

The way forward is to limit the global emissions of greenhouse gases, experts said, adding that there are no other viable long-term measures.

This year is being marked as the International Year of Glaciers’ Preservation by the United Nations (UN). Global leaders, policymakers, scientists and civil society members will attend a UN high-level event in Paris and New York on March 20 and 21 to address the crucial role of glaciers in the climate system and water availability.

Image Credits: WMO, World Glacier Monitoring Service (WGMS), C3S/ECMWF/WGMS.