Glaciers are the planet's frozen water banks. They sustain water supply, ecosystems and even cultural traditions. But many of these sprawling beds of ice are melting. Why does that matter?
The collapse of a glacier in theSwiss Alps this weekhas underscored the impacts of a warming world on the ice-packed parts of planet Earth.
When the meltingBirch Glacier on crumbled on Wednesday, it engulfed the picturesque village of Blatten in the country's southern Wallis region. Amound of debris has clogged the path of the Lonza River, increasing the risk of flooding.
Glaciers and ice sheets store about70% of the world's freshwater reserves. High-altitude regions are often dubbed the world's "water towers" because they gradually release meltwater in the summer, sustaining townsandfarmsdownstream.
Two billionpeople globally rely on glacial melt for their day-to-day water needs, researchers say. Yet,as the world gets hotter, the ice is thawing.
Glaciers around the world are now meltingat twice the rate measured just two decades ago. Between 2000 and 2023, they lost an ice mass equivalent to 46,000 Great Pyramids of Giza.
And this is affecting communities worldwide. Some regions are left with too little water, while others struggle with too much.
The residents of the small western Peruvian town of Huaraz draw almost 20% of their annual water supply from melting ice. But Andean glaciers are thawing even faster than elsewhere.This poses a risk of flooding. Ina decadelong lawsuit, one resident of Huarazsued a German energy company over the potential risk to his home from a mountain lake that is filling with meltwater at a rapid rate.
It's not only in Peru that huge glacial lakes form when glaciers thaw. Whenthey become too full, deadly floods can wash away buildings, bridges and wipe out fertile land, like in Pakistan,where a glacial lake burst inOctober 2023.
Thatsame month in neighboring India, a lake of melted ice overflowed and killed 179 people. Scientists estimate that globally, at least 15 million people are vulnerable to sudden flooding from thawing ice,mostofthem living inIndia andPakistan. Since 1990, the volume of water in mountain lakes there has increased by around 50%.
The collapse of the Birch Glacier in Switzerland caused a landslide of rock and ice that covered most of the 300-strong village of Blatten in mud. Though residents had been evacuated as a precaution, one man is missing inwhat scientists call the latest dramatic example of climate change's impact on the Alps.
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As glaciers shrink, they eventually reach a threshold — known as peak water — at which runoff declines. As a result, less meltwater flows downstream, with potentially far-reaching consequences.
Reduced water supply has forced local farmers, who traditionally grew corn and wheat, to change both their crops and water management. Some communities in the Andes have now switched to growing a bitter potato variety that is more resilient todrought.
Unstable water supply is alsostalling electricity production. In Chile, 27% of power is generated by hydroelectric dams which critically depend on meltwater. In 2021, the Alto Maipo plant was shut down due to dwindling flow.
Thermal expansion of ocean water due to increased temperatures is the main cause of rising sea levels, yet the meltingof glacial ice shields crucially contributes to it as well.
And it's not only glaciers in high altitudes that are melting, but also those in the ocean, likeThwaites Glacierin Western Antarctica. The majority of its ice shield is located on land, yet the glacier’s front extends some 50 km (30 miles) into a huge floating ice shelf. This frosty giant is the size of the US state of Florida and has been deemed "very unstable."Scientists have said it isthawing on all sides.
Thwaites Glacier has been dubbed "doomsday glacier" for its potential impact on what some researchers call "abrupt" sea level rise.
Inthe last 25 years alone,melting glaciers have caused global sea levels to riseby almost 2 centimeters (0.7 inches). This might not seem like much, but low-lying islands like Fiji and Vanuatu in thePacific Ocean are at risk of disappearingunder the waves.
In addition, more than 1 billion people in megacities like Jakarta, Mumbai, Lagos and Manila live within 10 kilometers (about 6 miles) of the coast. Protective dikes are only a temporary solution, assea levels continue to rise.
Glaciersalso hold spiritual and cultural significance.
Every year, tens of thousands of pilgrims gather at one of Peru's most sacred glaciers, the Colquepunco, for a religious festival.
In the past, ice blocks were carved from the glacier and carried down to local communities who believed in their healing properties. But as the glacier vanishes, this ancient tradition has come under threat.
ThePresena Glacier in Italy, a popular destination for skiers, has reportedly lost a third of its volume since 1990. Andnatural snow in the European Alps is expected to declineby 42% by the end of the century. Scientists estimate that many ski resorts worldwide won't be profitable in the future.
Localscan adapt to some of these dangers.In the Pakistani village ofHassanabad, an early warning system has been installed to monitor activity at the nearby Shisper Glacier. Should there be a need for a warning, it can be communicated through external speakers in the village.
In theneighboring Ladakh region, researchers are experimenting with growingartificial glaciersthat can mitigate water shortage in summer to meet this challenge.
But these strategiescan only work up to a point. Scientist say the best way to tackle receding glaciers is to slow the rising temperatures that are heating the Earth.
The article was updated on 6.02.25 to add information on the thermal expansion of oceans.
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