Introduction
Patagonia, the vast region spanning southern Chile and Argentina, is home to the largest concentration of glacial ice in the Southern Hemisphere outside Antarctica. Two immense ice fields, the Southern Patagonian Ice Field and the Northern Patagonian Ice Field, together cover over 16,800 km² and feed more than 50 major glaciers.
These ice fields are remnants of a much larger ice sheet that covered Patagonia during the last Ice Age. Today they straddle the Andes at the southern tip of South America, where relentless Pacific storms dump enormous quantities of snow on the high mountains, sustaining glaciers that flow down both the Chilean and Argentine flanks.
Geography & Dimensions
- Southern Patagonian Ice Field: 13,000 km² (3rd largest non-polar ice mass)
- Northern Patagonian Ice Field: 3,800 km²
- Major Glaciers: 50+ named glaciers
- Latitude: 46°S to 51°S
- Highest Point: Volcan Lautaro (3,623 m) on the Southern Ice Field
The Southern Patagonian Ice Field stretches roughly 350 km along the spine of the Andes, making it the largest temperate ice mass in the Southern Hemisphere and the third largest reserve of freshwater on Earth after Antarctica and Greenland. It feeds glaciers on both sides of the continental divide.
The Northern Patagonian Ice Field, separated from its southern counterpart by roughly 100 km, covers approximately 3,800 km². Together the two ice fields represent a globally significant mass of ice at relatively low latitudes, sustained by the extraordinary precipitation of the southern Andes. Key glaciers include Perito Moreno, Upsala, Viedma, Grey, O'Higgins, Jorge Montt, and San Rafael.
Formation & Movement
- Annual Precipitation: 5,000-10,000 mm on western slopes
- Key Glaciers: Perito Moreno, Upsala, Viedma, Grey, San Rafael, Jorge Montt
- Ice Flow Rates: Vary widely; San Rafael moves ~17 m/day
- Calving: Multiple glaciers calve into lakes and fjords
Patagonia's glaciers form from the prodigious snowfall that Pacific weather systems deliver to the western Andes. As moisture-laden air rises over the mountains, it cools and releases precipitation, with some western slopes receiving over 10,000 mm per year. This snow compresses into ice and flows downhill through valleys on both sides of the divide.
The glaciers display enormous diversity. Perito Moreno in Argentina is famous for its stability, while neighboring Upsala has been retreating rapidly. San Rafael Glacier in Chile is the nearest tidewater glacier to the equator in the Americas, calving into a fjord-like lagoon. Some glaciers terminate in freshwater lakes, others in Pacific fjords, and the dynamics of each are different.
Climate Impact
- Mass Loss Rate: ~17 Gt per year (Southern Ice Field alone)
- Retreating Glaciers: Most are retreating; Upsala, Jorge Montt among fastest
- Stable/Advancing: Perito Moreno (stable), Pio XI (advancing)
- Sea Level Contribution: Significant contributor from South American ice
The Patagonian Ice Fields are losing mass at an alarming rate. The Southern Patagonian Ice Field alone is estimated to be losing approximately 17 gigatonnes of ice per year, making it one of the largest contributors to sea level rise from mountain glaciers anywhere in the world.
The retreat is not uniform. While most glaciers are shrinking, Pio XI (Bruggen) Glacier on the western side is actually the largest glacier in South America and has been advancing in recent decades, possibly due to increased precipitation. Perito Moreno remains in rough equilibrium. But glaciers like Upsala, Viedma, and Jorge Montt have retreated dramatically, losing kilometers of length in recent decades.
Surrounding Ecology
- Western Slopes: Valdivian temperate rainforest
- Eastern Slopes: Patagonian steppe transitioning to beech forest
- Key Species: Huemul deer, puma, Andean condor, guanaco
- Protected Areas: Torres del Paine NP, Los Glaciares NP, Bernardo O'Higgins NP
The ecological contrast between the two sides of the Patagonian Ice Fields is striking. The western Chilean slopes receive heavy rainfall and are cloaked in dense Valdivian temperate rainforest, with towering alerce trees (Patagonian cypress), coigüe beech, and dense understory.
The eastern Argentine side lies in a rain shadow and transitions rapidly from southern beech forest to the dry Patagonian steppe. The huemul, a small endangered deer that appears on Chile's coat of arms, inhabits the forests near the glaciers. Pumas, guanacos, and Andean condors range across the broader landscape.
Exploration & Tourism
- Major Parks: Torres del Paine (Chile), Los Glaciares (Argentina)
- Famous Treks: W Trek, O Circuit (Torres del Paine), Huemul Circuit (El Chalten)
- Glacier Viewing: Perito Moreno walkways, Grey Glacier boat tours, San Rafael lagoon
- Access Points: El Calafate, El Chalten (Argentina); Puerto Natales, Coyhaique (Chile)
Patagonia's glaciers are major international tourist destinations. On the Argentine side, Los Glaciares National Park offers walkway views of Perito Moreno and trekking near the Fitz Roy massif from El Chalten. On the Chilean side, Torres del Paine National Park features the Grey Glacier and iconic granite towers.
More adventurous travelers can kayak to the face of Grey Glacier, take boat excursions to San Rafael Glacier's calving lagoon, or attempt the challenging Huemul Circuit that crosses glacial terrain near El Chalten. The ice fields themselves remain largely unexplored wilderness, with only a handful of full traverses ever completed due to ferocious weather and crevassed terrain.
Key Facts
- The Southern Patagonian Ice Field is the third largest non-polar ice mass on Earth.
- Together the two ice fields cover over 16,800 km² and feed 50+ major glaciers.
- The Southern Ice Field is losing approximately 17 gigatonnes of ice per year.
- Pio XI Glacier is South America's largest glacier and is one of the few that is advancing.
- San Rafael Glacier is the nearest tidewater glacier to the equator in the Americas.
Fun Facts
- The Southern Patagonian Ice Field has only been fully traversed on foot a handful of times, and several attempts have ended in rescue or tragedy.
- Pio XI Glacier advanced 5 km between 1945 and 2000, completely bucking the global retreat trend.
- The Patagonian Ice Fields were once part of a continuous ice sheet that covered all of southern South America during the last Ice Age.
- Winds on the ice fields can exceed 200 km/h, making them among the windiest non-polar places on Earth.
Final Thoughts
Patagonia's glaciers represent one of the last great frontiers of ice on Earth. From the thundering calving of Perito Moreno to the vast unexplored expanses of the Southern Ice Field, these frozen landscapes are both a reservoir of Earth's freshwater and a stark indicator of our changing climate. Their fate in the coming century will have consequences far beyond the mountains of South America.
