Modeling the Greenland Firn Aquifer and its ability to Hydrofracture a Crevasse to the Bed of the Ice Sheet

Abstract:

Spanning 1.7 million km² with glacial ice that exceeds 3,000 m thick in the interior, the Greenland ice sheet plays a large role in Earth’s response to climate change. A recently discovered firn aquifer within the ice sheet has the potential to buffer or enhance sea level rise by retaining water or outputting it into the ocean. This study examines englacial hydrology to determine if the subsurface aquifer can discharge its contents into the ocean via hydraulic fracturing of crevasses. Operation Ice Bridge data is utilized to map ice surface elevation profiles and water table return signals. This data is then modeled in SEEP2D, based on Darcy’s law, to determine the aquifer’s potential water discharge. With a known discharge, conservation of mass equations yield crevasse water depth. This water depth is converted into pressure and compared with known fracture thresholds to determine the likelihood of failure at varying crevasse dimensions. These results can be used to better assess the Greenland aquifer’s potential to alter sea level rise.