For Antarctic scientists, getting a handle on what’s happening under the ice shelves is urgent because the fate of the planet’s coastlines will depend on how fast they melt.

Antarctica has more than 70 ice shelves that extend the continent’s vast ice sheet out over the ocean.

Covering about 1.5m sq km, ice shelves float on the water and don’t by themselves push up global sea levels if they melt.

But if global heating of the ocean melts them from underneath they could become unstable, allowing the ice sheet to slide faster into the ocean, pushing up global sea levels by several metres.

The continent’s most vulnerable regions alone have enough ice to push up sea levels by about 15 metres if they all melt.