Providing fresh insights into assessing Antarctica’s likely contribution to future sea-level rise, a new study says that the Larsen C Ice Shelf — whose neighbours Larsen A and B, collapsed in 1995 and 2002, respectively — is thinning from both its surface and beneath.

Scientists were unable to determine whether it is warming air temperatures or warmer ocean currents that is causing the Antarctic Peninsula’s floating ice shelves to lose volume and become more vulnerable to collapse.

“We now know that two different processes are causing Larsen C to thin and become less stable. Air is being lost from the top layer of snow (called the firn), which is becoming more compacted — probably because of increased melting by a warmer atmosphere,” said lead author Paul Holland from British Antarctic Survey (BAS).

The team combined satellite data and eight radar surveys captured during a 15-year period from 1998 to 2012. Larsen C Ice Shelf lost an average of four metres of ice, and had lowered by an average of one metre at the surface.

The Antarctic Peninsula is one of the fastest warming regions on Earth, with a temperature rise of 2.5 degrees Celsius over the last 50 years.

“Understanding and counting up these small contributions from Larsen C and all the glaciers around the world is very important, if we are to project, with confidence, the rate of sea-level rise into the future,” concluded professor David Vaughan, glaciologist and director of science at BAS.

The study appeared in the journal The Cryosphere.