Greenland's ice melts four times faster than just 15 years ago, and large US coastal cities like New York can be overwhelmed, scientists have warned.
Ice melts faster than experts have thought before, and they say it is likely to lead to a faster rise in sea level due to the continuing accelerated warming of the earth's atmosphere.
The study flies in the face of US President Donald Trump, who has repeatedly denied the scientific consensus on climate change.
He once said the phenomenon was a Chinese fraud designed to harm US exports.
Researchers worried about global sea-level rise have focused on Greenland, where large glaciers overflow ice sheets of the iceberg in the Atlantic Ocean. The pieces are relaxed, eventually melting.
But a new study, published in the Protocols of the National Academy of Sciences, found that the biggest ice loss from the beginning of 2003 to mid-2013 came from the southwestern region of the country, which is mostly without large glaciers.
Major research author Professor Michael Bevis of the Ohio State University in the States said: "Whatever it is, it can not be explained with glaciers because there is not much there.
"It should have been the surface mass – the ice melts the interior of the coastline.
The melting, which according to Professor Bevis and his colleagues is largely caused by global warming, which means rising rivers of water flow into the ocean in the summer.
The key finding from their study is that parts of Greenland, which so far have not been considered a serious threat, will likely become the "major future actor" in rising sea levels.
Professor Bevis said, "We knew we had a big problem with increasing the cost of ice from some big nests at the exit.
"But now we recognize a second serious problem: more and more large amounts of ice will leave like melted water, like rivers that flow into the sea."
He said the findings could have "serious consequences" for US coastal cities, including New York and Miami, as well as island states that are particularly vulnerable to rising sea levels.
And he warned that there was no going back.
"The only thing we can do is adapt and mitigate further global warming –
"It's too late to have no effect," he added.
"This will lead to a further rise in the sea level, and we see that the ice sheet has failed."
Climate scientists and glaciologists have watched Greenland's ice sheet as a whole since 2002 when NASA and Germany joined forces to launch the Gravitational Recovery and Climate Experiment known as GRACE.
It includes twins that measure the loss of ice in Greenland. Satellite data showed that between 2002 and 2016 Greenland lost about 280 gigatons of ice a year, equivalent to a 0.03-inch annual sea level rise.
But the speed of ice loss across the island was far from stable.
Professor Bevis's team uses data from GRACE and GPS stations scattered around the coast of Greenland to identify changes in the ice mass.
The models they have found show a "worrying" trend – by 2012, ice is almost four times higher than in 2003.
And the biggest surprise was that the acceleration was concentrated in southwest Greenland, part of the island that was previously unknown to lose ice quickly.
The findings of the scientists are totally uncommon for Trump's views.
Just on Sunday, the American leader was ridiculed by the issue of climate change, as East America was affected by -22C.
He writes: "Be careful and try to stay in your house. Large parts of the country suffer from huge amounts of snow and near the record frost.
– Amazing how great this system is. It would not be bad to have a bit of this good old-fashioned global warming right now! "
Trump has moved to social media because of a lack of understanding of climate change, which confused him with just cold weather.