"The real worry now is just how much worse will it get", Bevis added, referring to the rising sea levels caused by the ice meltdown. "So why only now are they causing this massive melt?"
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 researchers analyzed data that were obtained in the framework of the mission GRACE (Gravity Recovery and Climate Experiment), and stated that the ice sheet of Greenland is melting faster than was thought before.
These grim conclusions came in the wake of a separate study last week that made similar warnings about Antarctica. But these new findings, Bevis said, show that scientists need to be watching the island's snowpack and ice fields more closely, especially in and near southwest Greenland.
But most of this ice loss is from the land-fast ice sheet itself, not Greenland's glaciers.
For the study published Monday in the Proceedings of the National Academy of Sciences, the team found the rate of ice loss had accelerated to almost four times what it was in 2003 by 2012, much of that coming not from glaciers calving into the sea but from large rivers of meltwater from the ice sheet itself.
The Greenland ice sheet covers nearly the entire island and extends over 1.7 million square kilometers.
If the entire ice sheet on Greenland melted, sea levels would rise by seven metres and drown most coastal areas.
Humans are melting the world's ice.
The ice melt accelerations in this region tracked a weather phenomenon known as the North Atlantic Oscillation (NAO). But the research shows the largest ice loss has actually taken place in a glacier-free part of Greenland. In Himalayas, which have the largest number of glaciers after the polar ice caps - more than thirty thousand sq.km of the Himalayan region is covered by the glaciers - the glaciers are disappearing faster every year, said a report, with some smaller glaciers now only half the size they were in the 1960s. That study, published earlier this month, found that Antarctic melting has raised global sea levels 1.4 centimeters between 1979 and 2017. "It's because the atmosphere is, at its baseline, warmer", Bevis said. However, the fact that the ice is melting faster and faster, even inland, and running out as a river of water, "that is a surprise", he included. "The water temperature fluctuations driven by an El Niño are riding this global ocean warming".
The effect of this finding is that south-west Greenland, which had not been considered a serious threat, now looks as if it will become a major future contributor to sea-level rise.
Prof. Bevis and his co-authors said they believe the melting ice sheet is mainly caused by global warming. The GPS network that monitor's the island's coastline is rather sparse n the southwest, and this needs to change in order to gather more reliable data. You never got four or five years of major melting like this in the 1900s.