Iceberg B-15

Iceberg B-15 is one of the world's largest recorded icebergs. It measured around 295 km long and 37 km wide (183-23 mi), with a surface area of 11,000 km² (4,250 mi²)  - larger than the island of Jamaica. The mass was estimated around three billion tonnes. After almost a decade, parts of B-15 still have not melted.

Background

Calved from the Ross Ice Shelf near Roosevelt Island in March 2000, B-15 broke up into several pieces in 2000, 2002 and 2003, the largest of which, B-15A, covered 6,400 km² of the sea surface. In November 2003, after the separation from B-15J iceberg, B-15A drifted away from Ross Island on the open waters of the Ross Sea.

In December 2003 a small knife-shaped iceberg, B-15K (about 300 km²), detached itself from the main body of B-15A and started drifting northward. In 2005 prevailing currents took B-15A slowly past the Drygalski Ice Tongue; the collision broke off the tip of Drygalski in mid-April. Then the iceberg sailed on along the coast leaving McMurdo Sound until it ran aground off Cape Adare in Victoria Land and broke into several smaller pieces on 27–28 October 2005. The largest piece was still named B-15A (now measuring approx. 1,700 km²), while three additional pieces were named B-15P, B-15M and B-15N. It then moved farther up north and broke up into more pieces. These were spotted by air force fisheries patrol on 3 November 2006. On 21 November 2006 several large pieces were seen just 60 km off the coast of Timaru, New Zealand. The largest measured about 1.8 km (~1 mi), rising 37 m (120 ft) from the surface of the ocean.

Effect on Antarctic ecology

On April 10, 2005 B-15A hit the Drygalski ice tongue, a projection of the fast-moving David Glacier that flows through Antarctica's mountainous Victoria Land coastal region, breaking off an 8 km² (3 mi²) section of the ice tongue. This collision with the Drygalski tongue forced a redrawing of Antarctic maps.

B-15A prevented ocean currents and winds from assisting in the 2004 - 2005 summer break-up of the sea ice in McMurdo Sound, and was an obstacle to the annual resupply ships to three research stations. The floe was expected to cause a catastrophic decline in the population of Adelie Penguins, as it added considerable distances which parent penguins must travel back from the sea to their chicks. Weddell seals and Skuas are also inhabitants of McMurdo Sound and their populations may have been affected as well.

In October 2006, it was noted by MacAyeal et al. (2006)  that a large storm in the Gulf of Alaska generated a trans-Pacific ocean swell that may have contributed to breaking B15-A into many pieces on October 27, 2005. The swell travelled 13,500 km (8,300 mi) from Alaska to Antarctica over six days. Scientists are studying this event as an example of how weather in one area can have effects in other parts of the world, and with concern over the effects on global warming. A more recent and detailed study by Martin et al. (2010), however, indicates that the iceberg breakup was principally caused by repeated grounding with near-coastal bathymetry near Cape Adare, Victoria Land.