Collaborative Research: Refreezing in the firn of the Greenland ice sheet: Spatiotemporal variability and implications for ice sheet mass balance

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The Arctic is warming and the Greenland ice sheet is melting. In total, the ice sheet stores enough water to raise sea level by approximately 6 meters. However, how surface meltwater generated in the summer makes its way from its location on the ice sheet to the ocean is not well understood. Two competing but not mutually exclusive theories are 1) the meltwater percolates into the ice sheet pores and is stored for a relatively long time. 2) The initial infiltrating meltwater refreezes at shallow depth in the firm, forming a hard pan that prohibits further infiltration. In this latter case, the meltwater quickly moves downslope along the surface of the ice sheet until it drains into the ocean. Rennermalm will test these hypotheses through a combination of field work, remote sensing from satellites, and modeling. Moreover, Rennermalm believes that during the most recent warming, the shallow refreezing mechanism has been playing a lesser role in the delivery of meltwater to the ocean than in previous times. To explore this hypothesis Rennermalm will compare the physical characteristics of modern cores with those extracted from earlier expeditions.The project will involve graduate and undergraduate student training. The PI?s will collaborate with the Rutgers Film Bureau to ensure effective communication with the public. The PI?s expect that the Rutgers Film Bureau director will seek to showcase the documentary at film festivals and other venues. In year one, two Rutgers Film Bureau members (the director and one student) will travel to Greenland to capture the day-to-day choices of scientific research in an extreme environment and produce a short multimedia narrative. Sea level is expected to rise in the decades to come, partially due to the melting of the Greenland ice sheet. However, we do not fully understand how meltwater generated on the surface of the ice sheet makes its way to the ocean. One line of thinking is that surface meltwater makes its way into the porous ice sheet where it is stored, either refrozen or in a liquid state, for relatively long times. Alternatively, as proposed by these investigators, the first seasonal meltwater that makes its way into the shallow ice, refreezes and blocks further infiltration, resulting in water that quickly moves down the surface ice sheet until it enters the ocean. Knowing the fate of meltwater is imperative if we are to understand how fast sea level will rise in the future. These investigators will integrate field work, computer modeling, and analyze data from satellites.