El Niño Is Melting Peru’s Glaciers Three Times Faster
Environment
Key Facts
—The loss. Peru has shed more than 42% of its glacier surface in six decades, about 700 square kilometres of ice.
—The accelerant. During El Niño Costero events the retreat runs up to three times faster than in a normal year.
—The hotspots. Áncash and Cusco lead the losses; Apurímac has lost 91% and Huancavelica 99% of their glacier surface.
—The danger. Shrinking ice swells glacial lakes, raising the risk of sudden outburst floods downstream.
—The source. The findings come from Peru’s state glacier institute, Inaigem, in a study of the past sixty years.
El Niño Costero, a coastal warming event off Peru and Ecuador, is driving glacier retreat up to three times faster than in a normal year. That acceleration explains why Peru has lost more than forty-two per cent of its glacier surface over six decades, even as a warming climate alone does not account for the pace.
The country has shed roughly seven hundred square kilometres of ice over the past six decades, according to a study by Inaigem, Peru’s national institute for glacier and mountain-ecosystem research.
The findings drew fresh attention around the first of July, when Peru celebrates Huascarán National Park, home to the country’s densest cluster of tropical glaciers in the Cordillera Blanca range of Áncash.
Why El Niño hits the Peru glaciers so hard
The trigger is a coastal warming event Peruvians call El Niño Costero, an unusual heating of the sea off Peru and Ecuador that also lifts air temperatures high in the Andes and changes how precipitation falls.
Glaciers grow by banking solid snowfall that compacts into ice. When the warming tips that precipitation from snow to rain, the rain erodes the surface and washes away the thin snow layer before it can harden, so the glacier never rebuilds what the melt season took.
There is a second mechanism. These events deposit more soot, or black carbon, on the ice, darkening it so it reflects less sunlight, absorbs more heat and melts faster still.
That soot comes from both nature and people, drifting up from wildfires and volcanic activity as well as the burning of fossil fuels and pasture land. It settles on high ice that would otherwise act as a bright mirror bouncing the sun’s energy back to space.
The combination is punishing for tropical glaciers, which sit close to their melting point year-round. Unlike ice near the poles, they have little margin to absorb a warmer, rainier, dirtier season before they start to shrink outright.
Water and flood risk for thousands
This is not only a matter of scenery. Glacier melt feeds the rivers and streams that supply drinking water, farms and ecosystems, and its loss steadily shrinks the water available to Andean communities, above all in the dry season.
The retreat also breeds danger. Melting ice forms and swells glacial lakes penned in by unstable walls of rock and debris, raising the risk of a sudden outburst flood that can bury towns and infrastructure downstream.
Peru knows this history intimately. A lake outburst above Huaraz killed roughly eighteen hundred people in nineteen forty-one, which is why Inaigem opened a national monitoring centre in May to watch high-risk lakes such as Palcacocha in real time.
A slow-burning risk with no easy fix
A lesser-known side effect is acid rock drainage. As ice retreats it exposes rock that was buried for millennia, and where that rock holds sulphur minerals, contact with water and oxygen produces highly acidic run-off that can turn streams an orange hue and foul community water sources.
Researchers say the fixes tried elsewhere, such as covering ice in reflective sheeting or building artificial glaciers, are impractical across Peru’s vast tropical ranges. The forward signal for a foreign reader is stark: with reversal unlikely, the country’s water security now hinges on adaptation, from flood defences to early-warning systems.
How much of the Peru glaciers have been lost?
According to Peru’s state institute Inaigem, the country has lost more than forty-two per cent of its glacier surface over the past sixty years, about seven hundred square kilometres of ice, with Áncash and Cusco suffering the heaviest losses.
Why does El Niño Costero speed up the melt?
It warms the sea and the Andean air so precipitation falls as rain rather than snow, eroding the ice instead of rebuilding it, and it deposits more soot that darkens the surface and makes it absorb extra heat, pushing the retreat up to three times faster.
What are the risks to people?
The melt reduces dry-season water supplies for communities and farms, raises the danger of sudden glacial-lake outburst floods that can bury downstream towns, and exposes sulphur-bearing rock that acidifies and contaminates water sources.
Frequently Asked Questions
How much glacier ice has Peru lost, and which regions have been hit hardest?
Peru has lost more than 42% of its glacier surface — around 700 square kilometres of ice — over the past 60 years, according to the state glacier institute Inaigem. Áncash and Cusco have suffered the heaviest losses overall, while Apurímac has lost 91% and Huancavelica has lost 99% of their glacier surface.
Why does El Niño Costero make glaciers melt so much faster?
El Niño Costero warms the air over the Andes so that precipitation falls as rain instead of snow, eroding the ice rather than rebuilding it, and it also deposits more soot on the glacier surface, which absorbs extra heat instead of reflecting sunlight. Together these two effects can push the rate of glacier retreat up to three times faster than in a normal year.
What dangers does shrinking glacier ice create for people living nearby?
As glaciers shrink, they feed less water to rivers and streams that communities and farms depend on, especially during the dry season. The melt also swells glacial lakes held back by unstable rock and debris, raising the risk of sudden outburst floods that can bury towns downstream — a danger Peru knows well from a 1941 lake outburst above Huaraz that killed roughly 1,800 people.
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