Scientists Warn Major Glaciers Won't 'Survive This Century,' With Grave Impacts for Billions

Scientists on Friday spent the United Nations' World Water Day and first-ever World Day for Glaciers warning about how fossil fuel-driven global warming melts ice across the planet, endangering freshwater resources and causing seas to rise, with implications for ecosystems, economies, and billions of people.

In a Friday statement, World Meteorological Organization Secretary-General Celeste Saulo pointed to a publication that the U.N. agency released earlier this week: "WMO's State of the Global Climate 2024 report confirmed that from 2022-224, we saw the largest three-year loss of glaciers on record."

"Seven of the 10 most negative mass balance years have occurred since 2016," Saulo continued. "Preservation of glaciers is not just an environmental, economic, and societal necessity. It's a matter of survival."

The WMO report was followed by the Friday launch of a 174-page document from the United Nations Educational, Scientific, and Cultural Organization (UNESCO) that stresses how "billions of people depend on the fresh water that flows from increasingly fragile mountain environments."

"As the water towers of the world, mountains are an essential source of fresh water for (irrigated) agriculture, power generation, industry, and large and growing populations—in the mountains and also downstream," the report details. "Generally, due to higher precipitation and lower evaporation, mountains supply more surface runoff per unit area than lowlands, providing 55-60% of global annual freshwater flows."

The document, The United Nations World Water Development Report 2025—Mountains and glaciers: Water towers, notes that "major cities that have been critically dependent on mountain waters include Addis Ababa, Barcelona, Bogotá, Jakarta, Kathmandu, La Paz, Lima, Los Angeles, Melbourne, Mexico City, New Delhi, New York, Quito, Rio de Janeiro, and Tokyo."

"Globally, up to two-thirds of irrigated agriculture may depend on mountain waters," the report states, "while the number of people in lowlands that strongly depend on water from mountains increased worldwide from around 0.6 billion in the 1960s to some 1.8 billion in the 2000s. An additional 1 billion people in the lowlands benefit from supportive mountain runoff contributions."

"Most of the world's glaciers, including those in mountains, are melting at an accelerated rate worldwide," the publication adds. "Combined with accelerating permafrost thaw, declining snow cover, and more erratic snowfall patterns... this will have significant and irreversible impacts on local, regional, and global hydrology, including water availability."

The UNESCO publication follows the international Glacier Mass Balance Intercomparison Exercise (GlaMBIE) team's study, published in the journal Nature last month, showing that glaciers have lost an average of 273 billion metric tons of ice annually since 2000.

That figure "amounts to what the entire global population consumes in 30 years, assuming three liters per person and day," Michael Zemp, a professor at Switzerland's University of Zurich and director of the World Glacier Monitoring Service who co-led the GlaMBIE study, explained at the time.

Zemp pointed to that finding and others on Friday, noting that from 2000-23, glacier melt caused global seas to rise 18 mm or about 0.7 inches. He said, "This might not sound much, but it has a big impact: Every millimeter [of] sea-level rise exposes an additional 200,000 to 300,000 people to annual flooding."

In a U.N. video, experts also highlighted parts of the globe that are particularly impacted by melting glaciers. Zemp explained that in "the European Alps, we are one of the regions that is most affected by climate change. Warming is about double the global average, and indeed, glaciers in the Alps are one of the most suffering around the world."

"We have lost, since 2000, almost 40% of the remaining ice. And that means under current melt rates, glaciers will not survive this century in the Alps," he warned.

Scientists are also concerned about the Hindu Kush in the Himalayas, which are often called the "third pole because they hold a lot of water resources," WMO's Sulagna Mishra said in the video. "Here, more than 120 million farmers in the downstream areas are impacted directly because of the melting of the glaciers."

"So, when there are a lot of floods, for example, happening because of melting of glaciers, the livelihoods are changed, people tend to migrate from one place to another," she continued. "So when you ask me how many people are actually impacted, it's really everyone."

As Carbon Briefreported Friday:

Dr. Aditi Mukherji—the director of the climate change, adaptation, and mitigation impact action platform of the CGIAR—tells Carbon Brief that the report is an important call for more "adaptation efforts and funding."

She says that mountain-dwelling communities are "already quite vulnerable due to their remote location and other developmental deficits" and are "increasingly losing their way of life due to no fault of theirs."

However, in some parts of the world, especially the United States, such calls face the pro-fossil fuel agenda of polluting companies and right-wing policymakers that are working to quash the movement for a just transition to clean energy by any means necessary.