A large cavity has formed under what has been described as one of the world's most dangerous glaciers, and could contribute to a significant bump in global sea levels, said NASA scientists.

A study led by the agency revealed a cavity about two-thirds the area of Manhattan and roughly 1,000 feet tall is growing under Thwaites Glacier in West Antarctica.

The cavity is large enough to have contained 14 billion tons of ice, most of which has melted within the last three years, say researchers.

"(The size of) a cavity under a glacier plays an important role in melting," said lead author Pietro Milillo of NASA's Jet Propulsion Laboratory in a statement. "As more heat and water get under the glacier, it melts faster."

The study was published Wednesday in the peer-reviewed journal Science Advances.

Thwaites has been described as one of the world's most dangerous glaciers because its demise could lead to rapid changes in global sea levels. JPL said the glacier, about the size of Florida, holds enough ice to raise ocean levels another two feet if it completely melts. It also backstops other glaciers capable to raising sea levels another eight feet.

Researchers discovered the cavity using ice-penetrating radar in NASA's Operation IceBridge, an airborne survey launched in 2010 to study polar ice.

Last year, the National Science Foundation and Britain's Natural Environment Research Council launched a joint program called the International Thwaites Glacier Collaboration to study the unstable glacier and its role in sea levels.

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