Implications of the Firn Aquifer
By Matt Owens February 24, 2014
H₂O is unlike almost all other naturally occurring substances. One of its remarkable characteristics is that when its liquid form solidifies, the resulting ice floats on the liquid. This density transition is central to why freezing water tends to tear up roads during harsh winters; and the same process likewise cracks open rocks, thereby helping to release vital mineral nutrients to the biosphere. Floating ice also protects lakes and oceans from freezing all the way to the bottom and therefore protects the life they contain during periods of prolonged cold. Considering the remarkable properties of water and ice, it's fitting that there continue to be surprising new discoveries by glaciologists studying the two polar ice sheets.
One of the most recent discoveries is a vast aquifer of liquid water that exists year-round in the very top layers of Greenland's ice sheet. Two questions immediately come to mind: How is it possible that a huge store of liquid water could be located within the ice, let alone at the top of the ice? And what are the implications for future rates of sea level rise?