Today marks the first ever World Glaciers Day, an occasion which the UN is using to spotlight these icy landscapes which are fast disappearing.
Glaciers are now 9,000 billion tonnes lighter than when records began in 1975, according to the World Glacier Monitoring Service (WGMS).
“This is equivalent to a huge ice block the size of Germany with a thickness of 25 metres,” says the service’s director, Prof. Dr. Michael Zemp.
As the planet warms up, glacier loss is accelerating. The World Meteorological Organisation (WMO)’s new State of the Global Climate report revealed that from 2022-2024, glaciers underwent their greatest three-year loss on record.
“Seven of the ten most negative mass balance years have occurred since 2016,” says WMO Secretary-General Celeste Saulo, referring to the difference between the amount of ice glaciers gain through snowfall and the amount they lose through seasonal melting.
This is triggering an “avalanche of cascading impacts”, the UN agency warns, from flooding to water scarcity and sea-level rise. “Preservation of glaciers is not just an environmental, economic and societal necessity,” says Saulo, “It’s a matter of survival.”
What does the depletion of ‘the world’s water towers’ mean for people?
There are more than 275,000 glaciers worldwide, covering approximately 700,000 square kilometres of ground. Alongside ice sheets, they store a whopping 70 per cent of global freshwater resources.
As the WMO puts it, high mountain regions are the world’s water towers. The depletion of glaciers threatens the supplies of hundreds of millions of people who live downstream and depend on the steady release of water stored over winter during the hottest and driest parts of the year.
In the short term, glacier melt increases natural hazards like floods. Currently, glaciers are the second-largest contributor to global sea-level rise, after the warming of the ocean.
They contributed 18 mm to global sea-level rise between the years 2000-2023, according to one recent study by a global consortium of hundreds of researchers called the Glacier Mass Balance Intercomparison Exercise (GlaMBIE).
"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,” says Zemp.
GlaMBIE found that between 2000 and 2023, glaciers lost on average 5 per cent of their remaining ice. But regionally, this loss ranged from 2 per cent in the Antarctic and Subantarctic Islands to almost 40 per cent in Central Europe.
Where are glaciers most at risk?
WMO and WGMS warn that many glaciers in Western Canada and the US, Scandinavia, Central Europe, the Caucasus, New Zealand, and the Tropics are at risk of melting entirely.
The 2024 hydrological year marked the third year in a row in which all 19 glacier regions experienced a net loss of mass, WMO observes. Glaciers in Scandinavia, Svalbard, and North Asia experienced their largest annual mass loss on record.
Inaugurated in the International Year of Glaciers’ Preservation, the first World Glacier Day (21 March) seeks to increase awareness of the vital role that glaciers, snow, and ice play in the climate system and hydrological cycle.
One glacier is especially in the limelight today. South Cascade Glacier in the Cascade Range of Washington, US, has been chosen as the first ‘Glacier of the Year’ - an accolade which celebrates the majesty of these icy landscapes and the dedication of glaciologists who watch over them.
“South Cascade Glacier exemplifies both the beauty of glaciers and the long-term commitment of dedicated scientists and volunteers who have collected direct field data to quantify glacier mass change for more than six decades”, says Caitlyn Florentine, co-investigator of the glacier from the US Geological Survey.
It has been continuously monitored since 1952 and provides one of the longest uninterrupted records of glaciological mass balance in the Western Hemisphere.
