Antarctica's Larsen B ice-shelf is on course to disintegrate completely within the next five years, according to a study by US space agency Nasa.

The 10,000-year-old ice-shelf, which partially collapsed in 2002, is "quickly weakening" and likely to "disintegrate completely" before the end of the decade, researchers have predicted, after observing warning signs including large developing cracks and faster-flowing tributary glaciers.

"These are warning signs that the remnant is disintegrating," said Ala Khazendar of Nasa's Jet Propulsion Laboratory in Pasadena, California.

"Although it's fascinating scientifically to have a front-row seat to watch the ice-shelf becoming unstable and breaking up, it's bad news for our planet. This ice-shelf has existed for at least 10,000 years, and soon it will be gone."

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The data for the study was collected by aircraft measuring ice surface elevations and bedrock depths and space-based "synthetic aperture radars" that have been operating since 1997.

The Larsen B ice-shelf is 1618sq km in area and 500m at its thickest point.

The studies have shown that two of the three glaciers feeding Larsen B have sped up markedly since the shelf split in 2002, with scientists now predicting that a major crack is likely to move all the way across the shelf, splintering the remnants into icebergs that will float away.

Scientists fear the cracking could cause the three glaciers - named Leppard, Flask and Starbuck - to accelerate rapidly towards the ocean.

"After the 2002 Larsen B collapse, the glaciers behind the collapsed part of the shelf accelerated as much as eightfold - comparable to a car accelerating from 55 to 440mph (88 to 708km/h)," said a Nasa release on the study published online in the journal Earth and Planetary Science Letters.