Researchers have discovered a new aquifer - spread over 70,000 sq km - in the Greenland ice sheet, that holds liquid water all year long in the otherwise perpetually frozen winter landscape.
The aquifer, discovered by the University of Utah researchers, is extensive, covering 27,000 square miles or 69929.7 square kilometres.
The reservoir is known as a "perennial firn aquifer" because water persists within the firn - layers of snow and ice that don't melt for at least one season.
Researchers believe it figures significantly in understanding the contribution of snow-melt and ice melt to rising sea levels.
"Of the current sea level rise, the Greenland Ice Sheet is the largest contributor - and it is melting at record levels," said Rick Forster, lead author of the research.
"So understanding the aquifer's capacity to store water from year to year is important because it fills a major gap in the overall equation of melt-water runoff and sea levels," said Forster.
Forster's team has been doing research in southeast Greenland since 2010 to measure snowfall accumulation and how it varies from year to year.
The area they study covers 14 per cent of southeast Greenland yet receives 32 per cent of the entire ice sheet's snowfall, but there has been little data gathered.
In 2010, the team drilled core samples in three locations on the ice for analysis. Team members returned in 2011 to approximately the same area, but at lower elevation.
Of the four core samples taken then, two came to the surface with liquid water pouring off the drill while the air temperatures were minus 4 degrees Fahrenheit.
The water was found at about 33 feet below the surface at the first hole and at 82 feet in the second hole.
"This discovery was a surprise. Although water discharge from streams in winter had been previously reported, and snow temperature data implied small amounts of water, no one had yet reported observing water in the firn that had persisted through the winter," Forster said.
"Here instead of the water being stored in the air space between subsurface rock particles, the water is stored in the air space between the ice particles, like the juice in a snow cone," said Forster.
"The surprising fact is the juice in this snow cone never freezes, even during the dark Greenland winter. Large amounts of snow fall on the surface late in the summer and quickly insulates the water from the subfreezing air temperatures above, allowing the water to persist all year long," he said.
Forster said the reservoir's exact role is unknown.
"It might conserve melt-water flow and thus help slow down the effects of climate change. But it may also have the opposite effect, providing lubrication to moving glaciers and exacerbating ice velocity and calving increasing the mass of ice loss to the global ocean," said Forster.
The study was published in the journal Nature Geoscience.