An ice shelf is a thick slab of ice, attached to a coastline and extending out over the ocean as a seaward extension of the grounded ice sheet. Ice shelves range in thickness from about 50 to 600 meters, and some shelves persist for thousands of years. They fringe the continent of Antarctica, and occupy a few fjords and bays along the Greenland and Ellesmere Island coasts. (An ice shelf occupying a fjord is sometimes called an ice tongue.) At their seaward edge, ice shelves periodically calve icebergs, some the size of a small U.S. state or European country. Because they are exposed to both warming air above and warming ocean below, ice shelves and ice tongues respond more quickly than ice sheets or glaciers to rising temperatures.
Most ice shelves are fed by inland glaciers. Together, an ice shelf and the glaciers feeding it can form a stable system, with the forces of outflow and back pressure balanced. Warmer temperatures can destabilize this system by increasing glacier flow speed and—more dramatically—by disintegrating the ice shelf. Without a shelf to slow its speed, the glacier accelerates. After the 2002 Larsen B Ice Shelf disintegration, nearby glaciers in the Antarctic Peninsula accelerated up to eight times their original speed over the next 18 months. Similar losses of ice tongues in Greenland have caused speed-ups of two to three times the flow rate in just one year
https://nsidc.org/cryosphere/sotc/iceshelves.html
By Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany - Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=973482
By Michael Van Woert, NOAA NESDIS, ORA - NOAA Corps Collection (Corp2621), Public Domain, https://commons.wikimedia.org/w/index.php?curid=43819