Iceberg A-76

News: Iceberg A-76 calved from the western side of the Ronne Ice Shelf in Antarctica and is now floating on the Weddell Sea. Measurements taken from satellites and planes confirm it’s now the world’s largest.

A-76 Iceberg

  • A-76 is the latest in a series of large ice blocks to dislodge in a region acutely vulnerable to climate change, although scientists said in this case it appeared to be part of a natural polar cycle.
  • The iceberg, measuring around 170 km long and 25 km wide, with an area of 4,320 sq km is now floating in the Weddell Sea.
  • Slightly larger than the Spanish island of Majorca, A-76 had been monitored by scientists since it began to separate from the Ronne Ice Shelf.
  • It joins the previous world’s largest title holder A-23A — approximately 3,880 sq. km. in size — which has remained in the same area since 1986.
  • A-76 was originally spotted by the British Antarctic Survey and the calving — the term used when an iceberg breaks off — was confirmed using images from the Copernicus satellite.

Key Concepts:

Iceberg:

  • An iceberg is ice that broke off from glaciers or shelf ice and is floating in open water. Icebergs travel with ocean currents and either get caught up in shallow waters or ground themselves. The US National Ice Center (USNIC) is the only organisation that names and tracks Antarctic Icebergs. Icebergs are named according to the Antarctic quadrant in which they are spotted.

Ice Shelves:

  • An ice shelf is a floating extension of land ice. The Antarctic continent is surrounded by ice shelves. The Ronne Ice Shelf on the flank of the Antarctic Peninsula is one of the largest of several enormous floating sheets of ice that connect to the continent’s landmass and extend out into the surrounding seas.

Iceberg Calving:

  • Calving is the glaciological term for the mechanical loss (or simply, breaking off) of ice from a glacier margin. Calving is most common when a glacier flows into water (i.e. lakes or the ocean) but can also occur on dry land, where it is known as dry calving. Up to the end of the 20th century, the Larsen Ice Shelf (on the West Antarctic Peninsula) had been stable for more than 10,000 years.
  • In 1995, however, a huge chunk broke off, followed by another in 2002.
  • This was followed by the breakup of the nearby Wilkins Ice Shelf in 2008 and 2009, and A68a in 2017.