(CNN) In the last 22 years, one giant glacier in Antarctica has retreated almost three miles. If it fully thaws, sea levels would rise almost 5 feet.

That's according to researchers at the University of California, Irvine and NASA's Jet Propulsion Laboratory. After their assessment of the Denman Glacier in East Antarctica , the team of researchers agreed: There's reason to be concerned.

"East Antarctica has long been thought to be less threatened," Eric Rignot, who co-authored the team's study "Geophysical Research Letters," said in a statement . "But as glaciers such as Denman have come under closer scrutiny by the cryosphere science community, we are now beginning to see evidence of potential marine ice sheet instability in this region."

Scientists have been more concerned about West Antarctica, where the ice has been melting faster in recent years, Rignot said. But the Denman Glacier is so big -- at around 10 miles wide -- that its potential impact on sea levels is "just as significant," he said.

Between 1979 and 2017, the glacier experienced a cumulative mass loss of 268 billion tons of ice, according to the study, which was published on Monday.

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