Germany’s Spiegel Online reports on new research on the Greenland ice sheet (cross-checked with two different methods that yielded the same result), showing that the ice is disappearing much faster than previously believed.

The dimensions of this frosty giant go way beyond human imagination. With a surface area spanning some 1.7 million square kilometers (656,000 square miles), a view of Greenland’s ice above the Sermeq-Kujalleq glacier near Ilulisat makes it seem endless. The idea that this sheet of ice, which is up to three kilometers thick in parts, is melting seems absurd in the extreme.

But the large number of gigantic icebergs — and the valley into which they are slowly sliding — tell a different story. Here, as elsewhere in Greenland, a gigantic upheaval is underway. In recent years, the glacier has receded by around 15 kilometers; the ongoing meltdown appears unstoppable. Just how quickly Greenland’s ice is melting remains a matter of some debate, but the melting ice is contributing to rising ocean levels — with potentially dramatic consequences for millions across the globe.

Were Greenland to lose all of its ice, sea levels would rise some seven meters higher than today’s levels. Such a scenario will not become reality overnight — indeed the process could last hundreds of years. But new results from a team of Dutch researchers suggest that conservative estimates as to the speed with which the ice is melting should be shelved. According to the study, the rate at which Greenland’s ice is melting has accelerated substantially in recent years.

There are, strictly speaking, two parallel processes responsible for the ice’s retreat. On the one hand, rising temperatures melt the ice on land while warmer ocean currents eat away at the glaciers that jut out into the ocean. A research team led by Michiel van den Broeke from the University of Utrecht reported in the most recent edition of the journal Science that the two processes are contributing equally to the disappearance of the ice sheet.

According to the new report, Greenland lost an estimated 1,500 gigatons (one gigaton is equal to 1 billion tons) of ice from the year 2000 to 2008. “That is at the upper end of recent estimates of Greenland mass loss using various other methods,” van den Broeke told SPIEGEL ONLINE. Between 2006 and 2008, the loss in weight totaled 273 gigatons per year, he said.

The scientists are convinced their results are accurate because they arrived at their numbers using two fundamentally different methods — both of which returned the same conclusion. On the one hand, they monitored the movement of the ice which they fed into a regional computer model. For a second data source, they used the Grace observation satellites, which measure the Earth’s gravitational field.