The world’s largest island entered the spotlight this summer after US President Donald Trump expressed a desire to buy it from Denmark. Although debate surrounding its status has since calmed down, the icy giant landmass is in the process of drastic natural changes.

The ice covering Greenland is becoming denser, with frozen slabs expanding in the area, a new study published in the scientific journal Nature has revealed. The process, said to have never been seen before by glaciologists, could result in melted water eventually running off into the sea, as it cannot soak through the ice into the land.

The authors of the research warn that this could contribute to a sea level rise and result in unexpected changes if the ice slabs continue to grow, turning Greenland into a runoff zone.

“We're watching an ice sheet rapidly transform its state in front of our eyes, which is terrifying”, said Mike MacFerrin, glaciologist at the University of Colorado who led the study.

According to the researchers, the area of the ice slab has grown by 65,000 square kilometres over just 14 years from 2001 for 2014.

As National Geographic explains, Greenland’s icy blanket is more like compressed snow than actual ice, so the glacier has a plenty of air pockets. Melted water is soaked up by this thick layer of snow, which is known as firn. However, as the research team discovered several years ago, a “turtle shell” has formed over this natural snow sponge, and the water has started flowing away, affecting local hydrology.

Modelling the process, the scientists concluded that the shell began to form in the early 2000s. Every year of extensive melting it is said to be getting thicker.

“Every handful of years, these big melt summers are doing a number on the firn. That’s causing this whole process to grow inland pretty quickly”, MacFerrin noted.

As a result, Greenland’s runoff zone has grown by 26 percent, adding about a millimetre to global sea levels. However, as the researchers calculated, runoff could increase dramatically and add up to 7.5 centimetres to sea-level rise under a worst-case scenario, with carbon emissions growing.