A trillion-tonne iceberg, measuring 5,800 square km and one of the biggest on record, calved away from the Larsen C Ice shelf in the Antarctic Peninsula between July 10 and 12, 2017.
Ice shelves are floating tongues of ice that extend over the surface of the ocean from glaciers grounded on land. Ice shelves surround 75 percent of the Antarctic’s coastline. A ‘healthy’ ice sheet produces large tabular icebergs quasi-periodically, as the ice mass gained through snowfall needs to be counterbalanced by ice loss through melting and iceberg calving.
However, the loss of mass through calving of a particularly big iceberg or through disintegration of an ice shelf, which might be linked to surface melting due to warm air temperature or erosion by warm sea water, can destabilize an ice sheet. The loss of the ice shelf itself will not result in a rise in sea level, as it is already floating on the ocean. But due to the loss of the resistance formerly provided by the ice shelf, glaciers can flow off the land and into the ocean at an increased speed, drift to warmer climates, and cause an increase in sea level.
The neighbouring ice shelves have gone through disintegration in 1995 (Larsen A Ice Shelf) and 2002 (Larsen B Ice Shelf) followed by an average ~300% acceleration in ice flow speed of the inland glacier, as well as a mass loss of between 22 and 40 gigatonnes of ice per year in 2006 (more than 10 times larger than the rate in 1996 and 2000). The fate of Larsen C ice shelf and the inland glacier will remain to be determined in the next years or decades.
If you want to watch the breaking-up and learn more about the events click the link below:
The Guardian: https://www.theguardian.com/world/video/2017/jul/12/vast-iceberg-splits-from-antarctic-ice-shelf-video-explainer
NASA: https://climate.nasa.gov/news/2606/massive-iceberg-breaks-off-from-antarctica/
Written by Yongmei Gong