Alaska is home to some of the world’s most impressive non-polar ice masses, covering approximately 5% of the state’s land area. These massive ice bodies profoundly influence ecosystems and geography. Glaciers act as vast reservoirs of fresh water, feeding numerous rivers and lakes and shaping the landscape. Identifying the single “biggest” is complex because the answer depends on the precise metric used for measurement. This article identifies the largest glacial system in Alaska and explores how scientists quantify these dynamic natural wonders.
The Largest Glacier System in Alaska
The Bering Glacier System holds the title of the largest glacier system in Alaska and all of North America outside of the Greenland ice sheet. This immense body of ice includes the main Bering Glacier and the vast Bagley Icefield, which serves as its primary accumulation zone. The system is fed by high-elevation snows from the St. Elias and Chugach Mountains. The Bering Glacier System is cited as the largest based on its sheer size, covering approximately 1,900 to 2,000 square miles (5,000 to 5,175 square kilometers). It stretches for more than 120 miles (190 kilometers), making it the definitive choice when measuring total surface extent.
How Glacial Size is Measured
The question of “biggest” is scientifically complex because glaciologists use different metrics to quantify a glacier’s size. The three primary measurements are total surface area, length, and total ice volume. Surface area and length are the easiest to determine, often calculated using satellite imagery and aerial photography. The Bering Glacier typically holds the title for largest area and longest length in North America. Total ice volume is a much more difficult measurement to obtain, as it requires knowing the ice thickness across the entire body, usually through radar and seismic surveys. While the Bering system has a vast surface area, a glacier with thicker ice might hold more total ice mass. Because obtaining a complete ice thickness map is difficult, a definitive “biggest by volume” is often based on models and estimates.
Location and Unique Dynamics
The Bering Glacier System is situated in southeastern Alaska, primarily within the Wrangell-St. Elias National Park and Preserve. It originates in the Bagley Icefield, high in the Chugach and St. Elias Mountains, and flows southward toward the Gulf of Alaska. Its terminus, or end point, currently rests in Vitus Lake, a large proglacial lake that has expanded rapidly as the glacier has retreated.
A distinctive feature of the Bering Glacier is its broad, flattened terminus known as a piedmont lobe. This type of glacier spreads out when it flows from a mountain valley onto a wide coastal plain. The glacier is also classified as a surging glacier, meaning its flow alternates between long periods of slow movement (the quiescent phase) and short periods of extremely rapid advance (a surge). During a surge event, the ice can move up to 100 times faster than normal, with the Bering Glacier having surged at least six times in the 20th century.
The glacier’s powerful surge cycles cause dramatic changes at its terminus, advancing into and reclaiming parts of Vitus Lake before retreating again. The terminus calves, or breaks off, icebergs into Vitus Lake, which is a tidally influenced body of water. This dynamic interaction between the massive, surging ice front and the expanding lake makes the Bering Glacier a subject of intense scientific study. Its retreat is also linked to an increase in the frequency of regional earthquakes due to the diminished weight of the ice on the Earth’s crust.
Other Alaskan Glacial Giants
While the Bering Glacier System is the largest overall, Alaska is home to several other glaciers that hold superlative titles based on specific characteristics.
- The Malaspina Glacier, located in the Wrangell-St. Elias National Park, is the world’s largest piedmont glacier. This feature is formed by the merger of several valley glaciers and covers an area of about 1,500 square miles (3,900 square kilometers).
- The Hubbard Glacier is North America’s longest tidewater glacier. It flows for over 75 miles from its source to its terminus in Disenchantment Bay. Tidewater glaciers terminate directly into the ocean.
- The Nabesna Glacier, also in Wrangell-St. Elias, holds the record as the world’s longest interior valley glacier.
Unlike many Alaskan tidewater glaciers, the Hubbard Glacier has exhibited stability and even periods of advance over the last century.