New climate models reveal rapid glacier melt in Patagonia – here’s why that matters

Patagonia’s glaciers have been shrinking faster than ever over the past two decades, and the reasons go far beyond simple warming. New research shows a deeper, long-term shift in the atmosphere is to blame. This shift has brought more warm air into the region, pushing the glaciers toward rapid melt and adding to global sea-level rise.

To understand how much ice has disappeared and why, a team of scientists from the University of Liège used powerful climate models. These models tracked the glacier surface mass balance—how much snow glaciers gain in winter and how much water they lose through melt, runoff, and evaporation—going all the way back to 1940.

Patagonia, located at the southern tip of South America, stretches across Chile and Argentina. This region holds the largest mass of ice in the Southern Hemisphere outside Antarctica. The Southern Andes mountains rise sharply across the landscape, splitting Patagonia into two very different sides.

“The Southern Andes act as a natural barrier, blocking moisture-laden westerly winds from the Pacific Ocean,” says Brice Noël, a climatologist involved in the study. Because of this barrier, glaciers on the western side can get more than 15 meters of snow each year.

This snow helps build the glaciers at high altitudes. But at lower elevations, especially near sea level, warmer air causes strong melting during summer. That meltwater flows into the ocean, slowly raising sea levels.

The research team rebuilt 83 years of glacier data using two advanced regional climate models. One of them, called MAR, came from the University of Liège. These models usually work on a 5-kilometer grid, which is too rough to catch the details of narrow glaciers found in Patagonia. So the team sharpened the grid down to 500 meters. This allowed them to track the melting and snowfall more precisely.

“Our high-resolution model closely aligns with in situ and satellite mass loss observations,” says Bert Wouters, a glaciologist from Delft University of Technology.

What the model showed was alarming. Since 1940, Patagonian glaciers have lost 1,350 gigatons of ice. That’s equal to about 3.7 millimeters of global sea-level rise. One gigaton equals a billion metric tons. That amount of water could fill over 500,000 Olympic-sized swimming pools. During just the last 20 years, this melting has added around 0.07 millimeters per year to global sea level. That may sound small, but when combined with other melting glaciers and polar ice sheets, it adds up quickly.

The study found something surprising. Snowfall in Patagonia has stayed about the same since the 1940s. So why are the glaciers disappearing so fast?

“We identify increased surface runoff as the primary driver of glacier mass loss,” explains Noël. Runoff is the water that melts off the glaciers and flows into rivers and oceans. As temperatures rose, more ice melted. But there’s another factor making things worse—firn loss.

Firn is the porous snow that sits on top of glaciers. It’s like a sponge that absorbs some meltwater and refreezes it, slowing runoff. But when this firn melts, it exposes darker, bare ice underneath. That darker surface absorbs more heat from the sun. As a result, the ice melts even faster. “Bare ice is darker than the surrounding firn, thus absorbing more solar energy in turn enhancing melt and runoff,” adds Stef Lhermitte of KU Leuven.

In short, it’s not just about warmer air. The glaciers are losing their natural defenses.

Another major cause of the increased melting comes from high above the Earth’s surface. For the last 40 years, a major atmospheric change has been happening. Subtropical high-pressure systems, which usually sit closer to the equator, have been moving toward the poles.

This shift brings more warm, northwesterly winds into Patagonia. The study found that temperatures at 850 hPa (a common level in the lower atmosphere used in climate studies) have warmed by about 0.14 degrees Celsius every decade.

“A poleward shift of the subtropical highs favours warm northwesterly air advections towards Patagonia,” says the research summary. This means more warm air gets funneled into the area, further increasing melt. These changing wind patterns are part of larger ocean and atmospheric systems, and researchers believe global warming is behind these shifts. “Ocean-atmosphere interactions underpinning this circulation change are driven by global warming and are likely to persist in the future,” warns the study.

If these trends continue, the future of Patagonia’s glaciers looks bleak. At the current rate of melting, scientists believe the glaciers could disappear in less than 250 years. That would not only raise sea levels by up to one more centimeter, but also hurt the communities in South America that depend on glacier meltwater during summer.

“Their disappearance would endanger South American communities reliant on summer meltwater supply,” says Noël. Glaciers serve as natural water towers. They collect snow in winter and slowly release water in warmer months. Without them, rivers may run dry when water is most needed. The loss of this ice will not only affect local regions but also contribute to rising seas that threaten coastal areas worldwide.

The strength of this research comes from its detailed look into the past. By using models and downscaling techniques, scientists were able to track changes over eight decades. This long-term view is key to understanding what’s happening now and what might come next.

Lower-resolution models from the past missed narrow glacier tongues and steep slopes. These features melt faster and influence how much water ends up in the sea. “High spatial resolution is essential to study the glacier surface mass balance in Patagonia,” says Noël.

This work adds to satellite data from missions like GRACE and GRACE-FO, which measure changes in Earth’s gravity caused by moving water and melting ice. Together, the models and satellite observations tell the same story: Patagonia is melting, fast.

Glacier melt in remote places like Patagonia might seem far away, but it connects to the entire planet. Even small rises in sea level threaten cities, farmlands, and ecosystems. Losing glaciers also means losing a vital source of fresh water for people and wildlife.

The glaciers of Patagonia have held on for thousands of years, shaped by storms, snow, and time. Now, they face a new threat—one that grows stronger with each passing year. The data is clear, and the challenge is global. What happens in Patagonia won’t stay in Patagonia.

Research findings are available online in the journal Nature Communications.

Note: The article above provided above by The Brighter Side of News.

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