Greenland’s massive ice stockpile is melting faster than previously thought, and it may be too late to do anything about it except “adapt,” scientists have warned in a new study.

The rate of ice loss there is up to four times faster than it was in 2003 and is contributing to rising sea levels, according to the new data.

The findings, published in the journal Proceedings of the National Academy of Sciences (PNAS), used NASA climate data and GPS stations to study Greenland’s ice sheets, the Guardian reports.

Greenland lost 280 billion tons of ice annually from 2002-2016, raising global sea levels by 0.03 inches per year. If Greenland’s entire ice sheet were to melt, oceans levels would swell up to 20 feet, endangering numerous seaside cities and low-lying Pacific islands.

“Increasingly, large amounts of ice mass are going to leave as meltwater, as rivers that flow into the sea,” Michael Bevis, the paper’s lead author and professor at Ohio State University, told the Guardian.

The ice is also melting four times faster in 2013 than it was in 2003, an increase scientists attributed to rising temperatures and the North Atlantic Oscillation, a pressure system that brings warmer air to Greenland.

“The only thing we can do is adapt and mitigate further global warming – it’s too late for there to be no effect,” Bevis added. “We are watching the ice sheet hit a tipping point.”

These grim conclusions came in the wake of a separate study last week that made similar warnings about Antarctica. Scientists from the University of California, Irving and Utrecht University in the Netherlands found that Antarctic ice loss has also rapidly accelerated over the past four decades, from about 40 billion tons per year in the 1980s, to over 250 billion tons per year from 2009–2017.

Scientists have warned that Antarctic ice melt could raise global sea levels 3.5 feet by 2100 unless urgent action is taken to limit greenhouse gas emissions.