image caption researchers were surprised to see liquid water coming up through the drill rig was used to extract old snow ( firn ) cores from within the greenland ice sheet all year round .
the water is stored in the air space between the ice .
the discovery will help scientists better understand the fate of greenland 's annual surface melt , which contributes to sea level rise .
 
big surprises still hide beneath the frozen surface of snowy greenland .
despite decades of poking and prodding by scientists , only now has the massive ice island revealed a hidden aquifer .
tracking this surface runoff helps scientists account for ice lost to melting each year .
until now , researchers thought most of this water went to the ocean or refroze on the ice .
the research is published in the journal , nature geoscience .