(AGENPARL) – Mon 24 March 2025 [cid:3cbb4a14-8f2c-4ab3-ac15-5dfe3f524785]
Glaciers on borrowed time
Capturing data from vanishing ice in Bolivia
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©Gerd Dercon
At 5 100 meters above sea level, the air around Bolivia’s Huayna Potosí glacier is thin, brittle with altitude. The wind moves over the ice in long, deliberate strokes, shaping a landscape caught between endurance and erosion. It is cold but not always freezing along the mountainside.
Where thick blue ice once filled the valley, bare rock now juts out like exposed bone. Year by year, the Western Huayna Potosí Glacier thins and retreats upslope at an annual rate of approximately 24 meters. In its wake, it leaves behind scattered stones and a meltwater lake, a body of water that did not exist in 1975, marking the glacier’s former boundaries.
Here, a team of scientists from the Andes and the Himalayas—representing Argentina, Bolivia, Chile, China, Ecuador and Nepal—wake before dawn to begin their ascent, knowing they must return before dark when the risk of accidents increases. The altitude makes breathing difficult, forcing them to move slowly, deliberately. They walk in single file, careful to avoid hidden crevasses that could swallow a person whole. At the centre of the glacier, they install a machine, an assemblage of panels and wires, to patiently decode the silence of the mountains.
Their work is supported technically by the Food and Agriculture Organization of the United Nations (FAO) and International Atomic Energy Agency (IAEA) through the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, and logistically and financially by the IAEA’s technical cooperation programme.
This cosmic ray neutron sensor, one of the two sensors painstakingly installed by the team on the glacier, measures easily, quickly and continuously how much water is accumulated on top of the glacier in the form of snow. This snow keeps the glacier alive. Each reading is a snapshot of the glacier’s diminishing existence.
The shrinking ice means more than just disappearing landscapes—it signals upheaval for those who rely on its water. The data that the scientists are collecting from these high-altitude glaciers is helping researchers predict the cascading effects of ice loss on ecosystems and local communities in order to find ways to adapt.
The device will stay long after the scientists descend, transmitting signals beyond the mountains via satellite—a digital memory preserving information about what the ice can no longer hold.
“Current glacial retreat now functions as a thermometer of accelerating climate shifts, with its rapid pace signalling the urgency of rising global temperatures,” says Gerd Dercon, Head of the Soil and Water Management and Crop Nutrition Laboratory of the Joint FAO/IAEA Centre. “As the ice melts and refreezes, it reveals not only the changes in climate but also the fragile dependencies human civilization has on these frozen reservoirs.”
In the valleys below, hundreds of thousands of people depend on the glacier’s water. Llamas and alpacas graze in the fertile grasslands, their pastures fed by the seasonal meltwater that has shaped this high-altitude ecosystem for centuries. Farmers equally rely on it to irrigate their crops and feed their livestock, while one million inhabitants of El Alto, a city close to Bolivia’s capital La Paz, depend on it for drinking water.
For generations, these ice fields have served as an unspoken contract between the mountain and those who live in its shadow, releasing water at a pace that allowed life to flourish. Now, that contract is breaking.
The reasons are clear. Rising global temperatures are melting glaciers around the world, but here in Bolivia, the crisis is accelerating. Sediments from ice-free areas are transported by strong winds and deposited onto the glacier, darkening its surface and increasing heat absorption.
By analysing sediments released from areas now exposed by glacial melt and accumulating in lakes and reservoirs, scientists are not only tracking the effect of the retreat of the ice on sediment distribution but also uncovering broader environmental shifts. These climate-driven changes may impact soil fertility, water quality, and water chemistry.
Cyclical weather patterns like El Niño amplify the warming, causing erratic swings in precipitation and rapid melting. Scientists predict that if these trends continue, the Western Huayna Potosí’s glacier—important for drinking water and once thought eternal by the locals—could vanish entirely in twenty years.
“Stopping the retreat of the glacier will not be possible,” says Dercon. “But we have to capture the water in several ways.” In Bolivia, communities have built more reservoirs, including smaller ones, dredged some old ones and raised the walls of dams. The land also needs to be worked differently, shaped to hold water rather than shed it, the soil taught to embrace. In this, reforesting the area with native trees and halting overgrazing of hungry llamas and livestock are fundamental changes for supporting healthy soils and land regeneration.
Raising awareness among decision makers and mobilizing resources to confront the coming changes is the first critical step and an important outcome of the expeditions. As has the establishment of an international monitoring network, across the Andes and the Himalayas. This network has provided insights into how the parts of the world covered by ice (known as the ‘cryosphere’) are impacted by climate change and how the retreating glaciers affect as well those who live downstream.
What is certain is that these glaciers, once thought immovable, are slipping away faster than predicted.
Now is the moment to conserve what remains. Governmental institutions and farmers in the Bolivian highlands are trying to capture the water being released through reservoirs and dams, for having larger buffer capacity. Further, new arrangements are being developed about the use of water, ensuring no conflicts happen in the future.
Working with governments and farmers to derive these solutions from the data collected on glaciers, the scientists, trained by FAO and IAEA through its Joint FAO/IAEA Centre and IAEA’s technical cooperation programme, help to raise awareness and finding solutions for a world that may one day be without glaciers.
The story and photos can be found here: https://www.fao.org/newsroom/story/glaciers-on-borrowed-time/en
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