Greenland's highly unstable ice sheet is melting more than seven percent faster than previously thought, scientists said this week after discovering a hotspot beneath the Earth's crust that was distorting their calculations.

The study in the journal Science Advances raises concern about the increasing impact of melting ice on sea level rise, since Greenland is the second largest ice sheet in the world after the one in Antarctica.

From 2003-2013 Greenland lost 2,700 gigatons (2,700 billion metric tons) of ice, not 2,500 gigatons as previously thought.

That means the ice sheet is losing about 20 gigatons more per year than the latest estimates.

The difference of 7.6 percent was described as ‘a fairly modest correction’ by lead author Michael Bevis, a professor of earth sciences at Ohio State University.

‘It doesn't change our estimates of the total mass loss all over Greenland by that much,’ Bevis said. ‘But it brings a more significant change to our understanding of where within the ice sheet that loss has happened, and where it is happening now.’

Using satellite data, researchers discovered that a hot column of partially molten rock in the Earth's mantle -- which also feeds Iceland's volcanoes -- had softened the rock beneath Greenland in a way that led scientists to underestimate the melting.

Bevis described Greenland's ice sheet as the world's ‘most unstable’ and said the latest research will ‘lead to better-informed projections of sea level rise.’