As much an icon of the polar regions as polar bears and penguins, these slabs of freshwater ice are the free-floating offspring of glaciers and ice shelves

Antarctic Peninsula

Icebergs: the children of glaciers

Few pieces of natural phenomena are more linked to Antarctica and the Arctic than icebergs. Even the least polar-inclined know the basics: Icebergs are chunks of floating ice, the bulk of their shape rests below the surface of the water, and one of them sank a very historic ship – while launching a number of cinematic careers. But there’s a lot more to these fascinating ice formations than that.

What Is an iceberg? Meaning, definition, facts

Ice shelves and glaciers are far from static; they are always either building up or breaking down. Especially in a warm climate, this breaking process (known as calving) is accelerated, and it often happens that a piece of ice breaks off from its glacial origin and falls into the water. The natural buoyancy of these freshwater ice fragments, which can contain air bubbles that are tens of thousands of years old, keep the calved chunks afloat. This is how icebergs are born. They can be as large as mountains or as small as mole hills, though take care not to confuse them with ice floes, which are flat (and smaller) sheets of broken sea ice.

Icebergs in Antarctica and the Arctic

Icebergs form in both the Arctic and Antarctica, though in different ways and in different forms. In the Arctic, icebergs commonly start their lives in the enormous Greenland Ice Sheet, which spills its frozen contents through openings in the mountain ranges that line the coast. Crevasses form in these glaciers due to the landscape’s irregular topography, leading to smaller icebergs that are more unusually shaped than those of Antarctica. Antarctic icebergs generally outsize their Arctic siblings, sometimes weighing several billion tons and possessing the dimensions of small islands. They calve off from floating ice shelves, which populate about 30% of the Antarctic shoreline.

The largest of the biggest: Larsen C, A68, and B-15

Though icebergs occur in both the far north and far south, Antarctica is known to produce the real behemoths. Some of the largest ice formations ever recorded, in fact, have made headlines in world news. In July 2017, the Larsen C Ice Shelf, the fourth largest ice shelf in Antarctica, produced one of the most colossal icebergs ever witnessed in the modern world: A68, larger than the state of Delaware and twice as large as Luxembourg. Years before this, in the spring of 2000, the B-15 iceberg broke off from Antarctica’s Ross Ice Shelf. B-15 remains the largest berg ever recorded. At its most massive, it was larger than the island of Jamaica, boasting 11,000 square km (4,200 square miles) of surface area, a width of 37 km (23 miles), and a length of 295 km (183 miles).

Ice shelves, glaciers, and global warming

When planetary climates rise, ice shelves and glaciers naturally melt and calve at a faster rate. This in turn leads to the production of more icebergs. Many scientists blame human-caused global warming, claiming that the calving of massive icebergs like B-15 and A68 is the direct result of carbon dioxide and other pollutants released into the atmosphere by industry. Other researchers, meanwhile, argue that calving is a natural process, and that the breaking off of giant icebergs is not necessarily a harbinger of worse human-caused ice conditions to come. 

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