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How icebergs are formed -

Icebergs are created from pure snow, making them fresh water. As snow accumulates over polar landmasses, the snow packs down to become ice, and this forms a glacier.

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Glacial origins -

When glaciers move in a downslope area, the forward motion of a glacier makes the front end unstable. As glaciers extend over the ocean, these front ends calve, or break off, and fall into the water.

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Influence of global warming -

Icebergs can also be formed when a glacier warms. This action creates a lake in the middle of the glacier. Meltwater carves out a depression, which in turn erodes the ends of the ice. Eventually they fall off due to gravity and form an iceberg. 

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Rising water levels -

As global warming increases temperatures, more icebergs are calving from melting ice caps. This results in more water flowing to the seas from glaciers and ice caps, and ocean water warming and expanding in volume.

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Bottom heavy -

An estimated 90% of an iceberg is below the waterline. This is due to the mass of water they carry.

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"Tip of the iceberg" -

Indeed, the "tip of the iceberg" belies the huge mass hidden underwater, which can vary in size depending on the amount of air trapped in the ice, and the volume of which can also affect the berg's buoyancy. Icebergs can contain up to 10% air bubbles by volume.

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Brash ice -

Brash ice is the accumulation of icebergs and floating ice not more than 2 m (6.5 ft) across. It is essentially the wreckage of other forms of ice.

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Tabular iceberg -

A tabular berg is an iceberg recognized by its long and wide flat-topped shape. They are formed when they split from the edges of ice shelves.

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Greenland icebergs -

Icebergs that calve from glaciers in Greenland and northern Canada are often irregularly shaped. This is because they originate in fjords containing fast-flowing glaciers originating from the inland ice sheet. Terminating below the snow line, these bergs shatter and are further broken up when they reach the sea, by wind and wave action.

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Antarctic icebergs -

Antarctic ice shelves often produce large tabular flat-toped icebergs. More geometric in shape, these bergs literally snap off the edges of ice sheets.

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Size matters -

Wind direction, temperatures, ocean currents, and numerous other factors determine the size of icebergs.

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USS Glacier -

According to Guinness World Records, the largest iceberg ever reliably documented was approximately 31,000 sq km (12,000 sq mi)—making it larger than Belgium. It was recorded west of Scott Island, in the Southern Ocean, by the icebreaker USS Glacier (pictured) on November 12, 1956.

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Largest iceberg in recent history -

Iceberg B-15 was the largest recorded iceberg in recent history. With a surface area of 11,000 sq km (4,247 sq mi)—roughly the size of the US state of Connecticut—when it broke free from Antarctica's Ross Ice Shelf in March 2000, B-15 eventually broke up into several smaller icebergs in October 2005.

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Largest current iceberg -

The largest iceberg currently afloat is that designated A-76, according to Guinness World Records. It was measured using satellite imagery on May 13, 2021 in Antarctica's Weddell Sea (pictured) with an estimated surface area of 4,320 sq km (1,670 sq mi).

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Antarctica's ice shelves -

In fact, the most colossal icebergs in the world—also recognized as ice islands—originate from Antarctica's expansive ice shelves.

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Atlantic icebergs -

Every year, roughly 40,000 medium to large sized icebergs calve off from Greenland. Actually, about 90% of North Atlantic icebergs come from the glaciers of Western Greenland.

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Labrador Current -

The Labrador Current plays a significant role in transporting icebergs from the glaciers of Greenland southwards into the trans-Atlantic shipping lanes. It flows southward along the west side of the Labrador Sea past Newfoundland and Labrador to continue south along the east coast of Canada near Nova Scotia.

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SS Kronprinz Wilhelm -

In July 1907, the German passenger liner SS Kronprinz Wilhelm rammed an iceberg and suffered a crushed bow, but was still able to complete her voyage. Five years later, however, another ocean liner wasn't so lucky.

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Killer berg -

This is the actual iceberg that caused the British luxury liner RMS Titanic to sink. A smudge of red paint much like the vessel's red hull stripe was seen near its base at the waterline. The 46,000-ton ship was still traveling at a speed of 23 knots, more than 40 km/h (25 mph), when she hit the iceberg in the North Atlantic Ocean on April 15, 1912.

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Monitoring and control -

Technology to detect rogue icebergs was in its infancy during the early years of the 20th century. In the wake of the Titanic disaster, the International Ice Patrol was established in 1914. By the late 1940s, radar was being used to monitor and track icebergs. In the 1960s, computer technology allowed for faster dissemination of data. The 1970s saw ice-breaking vessels equipped with satellite imagery capability. Pictured is three US Navy ships nudging a iceberg in McMurdo Sound, Antarctica, in December 1965.

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National Ice Center -

The only organization that names and tracks all Antarctic icebergs is the US-based National Ice Center, established in 1995. Icebergs must be a minimum of 19 km (11 mi) in length to be tracked by the NIC. This March 2002 image from the NIC shows a new iceberg, roughly twice the size of the state of Rhode Island, adrift in the icy waters off Antarctica. The iceberg, designated B-22, broke off from the Thwaites Ice Tongue, a peninsula of ice and snow extending from the mainland of Antarctica into the Amundsen Sea.

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Coastal crush -

Icebergs drift with the ocean currents. As a result, they sometimes end up getting caught in shallow waters or colliding against the shoreline.

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How old are icebergs? -

Icebergs can be as old as 15,000 years. For example, Newfoundland's icebergs are at least 10,000 years old, formed during the last ice age.

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Temperature control -

Icebergs are not the same temperature all the way through. While the core can be as cold as -15°C to -20°C (59°F to 68°F), the surface is the same temperature as the surrounding water, with the ice melting in warmer waters.

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Where does the word "iceberg" originate? -

The world iceberg comes from the Dutch term ijsber—ijs "ice" + berg "mountain." First recorded in the 1820s as a "detached piece of a glacier or ice pack at sea," the icebergs were previously known in 17th-century English as sea hills and islands of ice.

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Earliest photographs -

One of the first stories about Antarctica appeared in 1894 in National Geographic. In 1907, the magazine published some of the first-ever photos of the icy world. In 1924, photographs taken by British photographer Herbert Ponting exposed the region in even greater detail. Ponting also documented parts of the Terra Nova expedition (pictured), led by British explorer Robert Falcon Scott from 1910–1912.

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Stability -

An icebergs is unpredictable and may flip, or capsize, as it melts and breaks apart. Large icebergs that break off from a glacier front and flip onto the glacier face can push the entire glacier backwards for a few minutes. This phenomena is known as a glacial earthquake and can generate as much energy as a nuclear explosion.

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Mineral rich -

Generally snow white in color, icebergs can also appear brown after collecting sediment (rock and gravel), which become frozen in the ice. As the ice melts, it releases this debris, which can result in a fertilizing effect if it is rich in minerals.

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Iceberg Alley -

One of the best areas in the world to view the floating mountains of ice is the aptly-named Iceberg Alley, which stretches from the coast of Labrador to the southeast coast of the island of Newfoundland. Most of the more popular spots (like St. Anthony, Bonavista, Twillingate, and St. John's/Cape Spear) are accessible by road.

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Iceberg beer -

And if you're traveling in this part of the world, did you know that a beer is produced using iceberg meltwater? The Quidi Vidi Brewing Company, a craft brewery in Quidi Vidi village, a neighborhood of St. John's in Newfoundland and Labrador, Canada, is famous for its blue bottled Iceberg Beer, made with 20,000 year old iceberg water that is harvested from icebergs off the coast of Newfoundland.

Sources: (National Geographic) (United States Geological Survey) (The Canadian Encyclopedia) (Guinness World Records) (EarthSky) (The New York Times) (USNIC) (NPR)

See also: The most popular beers around the world

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