Andean glaciers largely sustain the livelihoods of 90 million people in South America and help provide half of the water for the Amazon River basin. Many of them, however, may “become unviable as water resources” by 2070 if global temperatures continue to rise at the current pace.

So says Jeremy Ely, senior lecturer at the University of Sheffield’s School of Geography and Planning and project lead of an on-going study carried out by a consortium of institutions based in the United Kingdom. “Projections are pretty difficult to make, but they’re also pretty scary,” Ely said in an interview for this article.

Glaciers are among mountain water sources referred to as “water towers of the world.” They serve as reservoirs, storing winter snowfall to be released as meltwater in the summer. Their retreat threatens drinking water supplies, sanitation, hydropower output and ecosystems that sustain everything from farming to wildlife habitat.

“Water towers in Latin America and the Caribbean occupy about one-third of the regional territory and produce more water flow per land area than any other continent,” stated the 2025 edition of The United Nations World Water Development Report, titled “Mountains and Glaciers: Water Towers.”

Venezuela’s Humboldt, or La Corona, glacier has dwindled to the point that last year it lost its classification as a glacier, though some of its ice remains. It was the sixth major glacier to essentially disappear from the Sierra Nevada de Mérida, making Venezuela the first country in the world to completely lose its glaciers in modern history, experts say. Overall, Andean glaciers are retreating 35% faster than the global average, according to a policy brief published by Ely’s research team.

The brief was distributed to accompany a presentation of the consortium study’s preliminary results at a two-day conference in March, held at Unesco headquarters in Paris to commemorate the World Day for Glaciers. The gathering was part of an effort by scientists, policymakers and activists to push for glacier preservation and meltwater resource adaptation at the COP30 UN Climate Change Summit in Brazil, in November.

During the Paris conference, global experts called for action to address what they repeatedly referred to as a “cryosphere crisis.” The strong language highlights how “we are triggering processes that might not be reversible,” said Julio Cordano, ambassador and director of environment, climate change and oceans at the Chilean Ministry of Foreign Affairs. “If that’s a crisis, then, yes, we’re in a crisis.” The discussion followed the publication of two important studies on glaciers in the scientific journals Science and Nature in August 2024 and March of this year, respectively.

The Science paper looked at a group of Andean tropical glaciers, including the Quesque in Peru. It concluded that Andean glaciers are almost certainly the smallest they have been in at least 11,700 years. The researchers, led by Andrew Gorin of the University of California, Berkeley, found many glaciers have reached “peak water,” a point at which the meltwater supplying downstream water sources begins drying up.

As higher temperatures melt glaciers at a faster rate, seasonal snowfall becomes insufficient to replenish the mass of ice. For a time, water flows remain robust, even increasing, thereby causing little disturbance for downstream populations and ecosystems that depend on meltwater rivers. However, once a glacier shrinks by a certain amount, the volumes begin to taper off.

Nature published a global study of 19 regions that included the Andes. It determined that the Southern Andes, at 10%, ranked as the fourth largest contributor to “global glacier mass loss” following Alaska, the Canadian Arctic, and peripheral glaciers in Greenland. The study was carried out by a consortium called the Glacier Mass Balance Intercomparison Exercise (GlaMBIE), headed by European scientists.

Local scientists have reached similar conclusions. In the Southern Andes, the glacier-fed Vilcanota River basin in Cusco, Peru is considered to be in a “critical situation” and is projected to suffer from “an imbalance between water demand and availability around 2050,” says Pedro Rau of the Water Research and Technology Center (CITA) at the University of Engineering and Technology in Lima.

This could affect cities including Cusco and Sicuani, says Rau, adding: “In the Central Andes, in the Lima and Junín regions, we have found some critical projections of glacier retreat [by 2050] reaching a loss of 84-98% of total glacier area.”

Not all glaciers are created equal. Nowhere is this more evident than in the Andes, where they are classified in three main categories. From north to south, these are glaciers of the Tropical Andes, marked by high elevations and year-round melt; the Dry Andes, where glaciers form in desert conditions and tend to be smaller and fewer in number, with the permafrost storing most of the ice reserve; and the Wet Andes, roughly Patagonia, with more snowfall and larger icefields. “The Andes is such a unique place; it’s long and thin and tall,” said Ely. “It covers a large latitudinal span. There are lots of different climate drivers and glaciers across the Andes.”

Given broad differences, combined with localized peculiarities, not everyone is convinced glaciers will disappear in one fell swoop. “It is a question for me, whether we will lose all the ice,” said James McPhee, professor of civil engineering at the University of Chile in Santiago. Some glaciers may disappear, but others might reach a new equilibrium, he said.

Take the sometimes paradoxical effects of so-called “dirty glaciers.” As a geologically young mountain range, the Andes is “constantly being weathered and it’s lifting,” thereby “producing a lot of debris, which falls on top of the glacier,” McPhee said. In periods of normal snowfall, the melt washes away the debris and the cycle reverts to normal. But during a drought, such as the prolonged one affecting Chile, debris accumulates on the mountain slopes atop of the ice.

The effect extends beyond aesthetics. “If you deposit a fine layer of debris on top of ice or snow, it decreases something called the albedo—the reflecting property of ice,” he said. “The light doesn’t get reflected and, of course, this energy gets absorbed by the ice. It raises the temperature and promotes melt.”

But if the debris piles up, it forms a protective layer that insulates the ice from the atmospheric heat. The melt rate can drop by 10 or 20 times. “We may see a future where many of these clean glaciers get very small or disappear completely, but many of the covered glaciers and rock glaciers are still present,” McPhee said.

Those conventional dirty glaciers are being joined in the Andes more recently by the accumulation of black carbon, or soot—the biggest source of which is fire in the Amazon forest, according to research by Heitor Evangelista of the Laboratory of Radioecology and Global Changes (LARAMG) at the Rio de Janeiro State University (UERJ) in Rio de Janeiro.

Given the multitude of factors, timelines will be different. “A mountain glacier can retreat and then form a new stable equilibrium, but flat ice caps can’t do that,” said Bethan Davies, professor of glaciology at Newcastle University, and a member of the British research team. “There are also tipping points associated with meltwater in the snow. If it becomes too warm in the snow, that meltwater no longer refreezes and we get a really sharp acceleration of melt. So, there are tipping points, but there’s no one universal tipping point.”

Localized mining threats

One visible and controversial human intervention is mining. The UN report touches on “water-related social conflicts […] in high elevation areas of Andean countries, many of which can be attributed partially to mining activities.” It cited the example of mining in the mountain range between Copiapó and Rancagua, in Chile.

Andean policymakers have taken steps to protect glaciers from mining and other threats, but the results are mixed. Argentina passed a strict glacier-protection law in 2010. Its mining provisions were upheld by the Supreme Court in 2019, but environmental protections now appear to be under attack by President Javier Milei.

Green legislators have unsuccessfully proposed a similar law in Chile, where many glaciers are already protected as part of national parks. Numerous glaciers are also within national parks in Bolivia and Colombia.

Peru has moved to boost the protection of ecosystems, including glaciers, from mining and other activities in recent years. “However, in my opinion, it needs more coverage and financial help,” said Rau.

At the Unesco conference in Paris, threats posed by mining played a barely audible second fiddle to concerns about global climate change.

“With regards to mining, this is locally very important in certain valleys, where on specific glaciers in specific places it can impact glacier health and dynamics,” explained Davies. “However, in the broader scale, this is rather insignificant in that it doesn’t impact many people or many environments on regional to global scales. Water resources, hazards from glacier lake outburst floods and sea-level rise are much larger issues that affect many more people worldwide.”

Calls for cooperation

Reflecting consensus at the conference, Cordano stressed: “We believe the only way to solve the climate crisis [… and] all these problems we are facing, is through multilateralism.”

Chile and Iceland are spearheading an intergovernmental group on sea-level rise and mountain water resources called Ambition of Melting Ice. Launched in 2022 with 20 members, including Peru and Mexico, during COP27 in Sharm El Sheikh, Egypt, the group has grown to 30, Cordano says.

He describes its message this way: “We need to reduce emissions globally if we really want to keep cryosphere, and all the ecosystem services” it provides.

Meanwhile, many researchers look to water basins for adaptive solutions. “We’re actually moving the project in a surprising way from the glaciers to the wetlands that exist in front of these glaciers to see how much water they can store, which is kind of sad to say, especially as a glaciologist,” said Ely. “We’re losing so much ice that we’re having to turn to the soil and the vegetation to see how much water they can store.”

Creative policymaking may be needed to bring modern science and technology, as well as traditional water-management techniques, to bear on the larger problem. Take groundwater recharging—a traditional practice that can be enhanced by modern approaches. A stumbling block is water-rights ownership, McPhee notes. “Water rights are owned by individuals or organizations,” he said. “When you put water into the ground, you’re losing [some] because the water will flow, and you will lose some control.”

Even if glaciers essentially disappear, the water itself might not, pointed out Wouter Buytaert, professor of hydrology and water resources at Imperial College London, and a member of the British research team. “We will not necessarily lose the water. It’s more of a shift in the way water runs off and ends up in the rivers.”