page_title: Larsen Ice Shelf
section_title: Larsen C
hierarchical_section_title: Larsen Ice Shelf / Ice shelf / Breakup / Larsen C
caption_attribution_description: English: The fractured berg and shelf are visible in these images, acquired on July 21, 2017, by the Thermal Infrared Sensor (TIRS) on the Landsat 8 satellite. The false-color view shows the relative warmth or coolness across the region. White indicates where the ice or water surface is warmest, most notably in the widening strip of mélange between the main iceberg and the remaining ice shelf. Dark grays and blacks are the coldest areas of ice.
context_page_description: The Larsen Ice Shelf is a long ice shelf in the northwest part of the Weddell Sea, extending along the east coast of the Antarctic Peninsula from Cape Longing to Smith Peninsula. It is named for Captain Carl Anton Larsen, the master of the Norwegian whaling vessel Jason, who sailed along the ice front as far as 68°10' South during December 1893. In finer detail, the Larsen Ice Shelf is a series of shelves that occupy distinct embayments along the coast. From north to south, the segments are called Larsen A, Larsen B, and Larsen C by researchers who work in the area. Further south, Larsen D and the much smaller Larsen E, F and G are also named.
  The breakup of the ice shelf since the mid-1990s has been widely reported, with the collapse of Larsen B in 2002 being particularly dramatic. A large section of the Larsen C shelf broke away in July 2017 to form an iceberg known as A-68.
  The ice shelf originally covered an area of 85,000 square kilometres, but following the disintegration in the north and the break away of iceberg A-17, it now covers an area of 67,000 square kilometres.
context_section_description: As of July 2017, Larsen C was the fourth largest ice shelf in Antarctica, with an area of about 44,200 km² (17,100 sq mi).
  Satellite radar altimeter measurements show that between 1992 and 2001, the Larsen Ice Shelf thinned by up to 0.27 ± 0.11 meters per year. In 2004, a report concluded that although the remaining Larsen C region appeared to be relatively stable, continued warming could lead to its breakup within the following decade.
  The breakaway process for the iceberg had begun by mid-2016. On 10 November 2016 scientists photographed the growing rift running along the Larsen C ice shelf, showing it running about 110 kilometres (68 mi) long with a width of more than 91 m (299 ft), and a depth of 500 m (1,600 ft). By December 2016, the rift had extended another 21 km (13 mi) to the point where only 20 km (12 mi) of unbroken ice remained and calving was considered to be a certainty in 2017.  This was predicted to cause the calving of between nine and twelve percent of the ice shelf, 6,000 km² (2,300 sq mi), an area greater than the US state of Delaware, or twice the size of Luxembourg. The calved fragment was predicted to be 350 m (1,150 ft) thick and to have an area of about 5,000 km² (1,900 sq mi). The resulting iceberg was predicted to be among the largest icebergs ever recorded, unless it would break into multiple pieces.
  On 1 May 2017 members of MIDAS reported that satellite images showed a new crack, around 15 km (9 mi) long, branching off the main crack approximately 10 km (6 mi) behind the previous tip, heading toward the ice front.  Scientists with Swansea University in the UK say the crack lengthened 18 km (11 mi) from 25 May to 31 May, and that less than 13 km (8 mi) of ice is all that prevents the birth of an enormous iceberg. "The rift tip appears also to have turned significantly towards the ice front, indicating that the time of calving is probably very close," Adrian Luckman and Martin O'Leary wrote on Wednesday in a blog post for the Impact of Melt on Ice Shelf Dynamics and Stability project, or MIDAS. "There appears to be very little to prevent the iceberg from breaking away completely."  The larger swath of the Larsen C ice shelf that sat behind the calved iceberg "will be less stable than it was prior to the rift" and may rapidly disintegrate in the same manner as Larsen B did in 2002.
  In June 2017 the speed of the imminent Larsen C iceberg accelerated, with the eastern end moving at 10 metres (33 ft) per day away from the main shelf. As discussed by the Project MIDAS researchers on their site: "In another sign that the iceberg calving is imminent, the soon-to-be-iceberg part of Larsen C ice shelf has tripled in speed to more than 10 meters per day between 24 and 27 June 2017. The iceberg remains attached to the ice shelf, but its outer end is moving at the highest speed ever recorded on this ice shelf."
  On 7 July the Project MIDAS blog report stated:  "The latest data from 6th July reveal that, in a release of built-up stresses, the rift branched several times. Using data from ESA's Sentinel-1 satellites, we can see that there are multiple rift tips now within 5 km (3.10 miles) of the ice edge. We expect that these rifts will lead to the formation of several smaller icebergs."
  On 12 July 2017, Project MIDAS announced that a large, 5,800-square-kilometre (2,200 sq mi) portion of Larsen C had broken from the main ice shelf at some point between 10 and 12 July. The iceberg, designated A-68, weighs more than a trillion tons and is more than 200 m (700 ft) thick. 
  Project MIDAS updated their blog information on 19 July 2017 regarding Larsen C by revealing that a possible new rift appeared to be extending northwards from the point where A-68 had broken off in mid-July. The project researchers felt this questionable new rift might turn towards the shelf edge, compounding the risk that it would "continue on to Bawden ice rise" which is considered "a crucial point of stabilization for Larsen C Ice Shelf." 
  As is true of all floating ice shelves, A68's departure from Antarctica had no immediate effect on gl
caption: The fractured berg and shelf are visible in this image acquired by the Thermal Infrared Sensor (TIRS) on the Landsat 8 satellite on 21 July 2017 (Lighter = warmer).
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