Giant cavity in Antarctic glacier signals rapid decay

017 thwaites glacer

Thwaites Glacier, one of the hardest places to reach on Earth, is responsible for around 4% of the global sea rise.

Researchers say a massive cavity the size of two-thirds of Manhattan was found under a glacier in Antarctica. This cavern is estimated to have once contained 14 billion tons of ice but, alarmingly, "most of that ice melted over the last three years " according to NASA scientists.

Scientists from NASA have discovered a enormous cavity, nearly 300 metres tall, growing at the bottom of the Thwaites Glacier in West Antarctica, indicating acceleration in rising global sea levels due to climate change.

Lead author Pietro Milillo of JPL says the size of the cavity under the glacier "plays an important role in melting".

Thwaites Glacier alone holds enough ice above sea level to raise sea levels by more than 65cm if it was to melt. Rignot is a co-author of the new study, which was published today in Science Advances.

JPL said that the findings "highlight the need for detailed observations of Antarctic glaciers' undersides in calculating how fast global sea levels will rise in response to climate change".

Researchers have previously warned that the huge Thwaites glacier could trigger a runaway ice sheet collapse which could raise global sea levels by 10 feet.

The Thwaites Glacier is now responsible for 4 percent of global sea level rise.

Scientists used a combination of ice-penetrating radar flown on NASA planes and European satellite data to capture what's going on.

The US National Science Foundation and British National Environmental Research Council have initiated a five-year field project, The International Thwaites Glacier Collaboration.

In Thwaites' case, that radar uncovered a big cavern between the glacier itself and the bedrock below it.

The discovery of cavity beneath Thwaites Glacier along with a number of other disconcerting features offer a new wrinkle to the harrowing tale of West Antarctica.

"We are discovering different mechanisms of retreat". Scientists have long thought that the glacier was not attached firmly to the bedrock beneath it.

The glacier isn't retreating uniformly.

In that region, the rate of grounding-line retreat doubled from about 0.6 kilometers a year from 1992 to 2011 to 1.2 kilometers a year from 2011 to 2017, researchers said.

The newly discovered cavity sits on the western side of the glacier, where the melt rate was found to be fastest. The disappearance of the ice mass would cause sea levels to rise by about two feet as well as making surrounding glaciers more likely to melt rapidly-which could cause an eight foot rise.

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