The recent occurrence of calving, the breaking off of ice from a glacier or shelf ice, in the Ronne Ice Shelf located in Antarctica’s Weddell Sea has resulted in the creation of the world’s largest iceberg. Named A-76, the newly-formed iceberg covers an area of around 4320 square kilometers.
A-76 Emerges as the Largest Iceberg
A-76 was spotted in the latest satellite images taken by the Copernicus Sentinel-1 mission – a part of the European Space Agency (ESA)’s Copernicus initiative which focuses on earth observation. This mammoth iceberg displaces the former record-holder, the A-23A iceberg (located in the same sea and measuring approximately 3,380 sq km), to the second position.
Nature and Naming of Icebergs
Icebergs are essentially fragments that have separated from glaciers or shelf ice, floating freely in open waters. These large pieces of drifting ice, carried by ocean currents, often end up stuck in shallow waters or possibly ground themselves. The US National Ice Center (USNIC) holds the distinction of being the sole organisation responsible for naming and monitoring Antarctic icebergs, as per the quadrant they originate from.
The Role of Ice Shelves
Ice shelves play a significant role in the geography and climate of Antarctica. As floating extensions of land ice, these expansive bodies envelop the continent, linking the landmass to the adjacent seas. Among the largest ice shelves, the Ronne Ice Shelf situated on the edge of the Antarctic Peninsula is notable.
Understanding Iceberg Calving
The process that results in the splitting off of ice from the edge of a glacier is termed “calving”. It predominantly happens when a glacier comes into contact with water bodies such as lakes or oceans. There also exist instances of calving on dry land, known as “dry calving”.
Notable Cases of Iceberg Calving
Historically, the Larsen Ice Shelf, located on the West Antarctic Peninsula, maintained stability for over 10 millennia until the end of the 20th century. However, significant portions started breaking off from 1995 onwards, with another drastic event in 2002. This was followed by the disintegration of the neighboring Wilkins Ice Shelf in the years 2008 and 2009, and the A68a in 2017.
The Link between Calving and Climate Change
Even though occasional calving is a part of the natural order, climate change has significantly accelerated this process. Data indicates that since 1880, average sea levels have surged about nine inches, with roughly a quarter of this rise attributed to melting ice in the Greenland and Antarctica ice sheets, coupled with land-based glaciers elsewhere. Recent research even indicates that the revised, more aggressive national goals set to reduce greenhouse gas emissions and mitigate climate change are insufficient in halting rising sea levels. The study warns that melting glaciers and ice sheets would lead to double the rate of sea level rise than if countries adhered to their initial commitments under the Paris Agreement.
