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Noon seminar - Following the water on the Greenland ice sheet: Re-freezing in firn, supraglacial...

Monday, March 02, 2020, 12:15PM - 1:15PM


Asa Rennermalm



SEEC S228 (Sievers Room)

Full title

Following the water on the Greenland ice sheet: Re-freezing in firn, supraglacial streams & rivers


An enormous amount of meltwater forms on the Greenland ice sheet surface each summer. Slightly more than half of that meltwater outflows into the oceans, and the remaining water infiltrate into firn (snow surviving at least one melting season) where may refreeze and form ice lenses. Previous studies conducted after the huge melt year of 2012, show that when these ice lenses become meter thick, they may prevent further infiltration into firn. Instead of refreezing, meltwater forms supraglacial channels and runoff to the ocean where it may raise global sea levels. Here we examine the spatial variability of ice lens distributions in twelve 5 to 20 meter firn cores collected in 2017 and 2018 at six sites in Southwest Greenland. At two locations, we can compare our cores with cores collected in 1989 and 1998, respectively. While we do not find evidence of meter thick ice lenses at our sites, our findings show that firn pore space is rapidly diminishing. Thus, the Greenland ice sheet firn’s capability to absorb future increases in ice sheet surface melting is being eroded and may eventually amplify global sea level rise.


Åsa Rennermalm is an associate professor at the Department of Geography at Rutgers, The State University of New Jersey. Her research interest is hydrology and glaciology of the Arctic region. Currently, she is studying the Greenland ice sheet to understand how much meltwater escapes to the ocean where it affects marine environments and raise global sea levels. Her work centers around field data collection and analysis, but also involves models and satellite data. She has participated in several Arctic field expeditions. Before coming to Rutgers, she was a postdoctoral researcher at Department of Geography at University of California Los Angeles. Her Ph.D is from Civil and Environmental Engineering at Princeton University, and she has a master and undergraduate degree from the University of Copenhagen in Denmark.


Coffee and cookies will be served before the talk - come to meet up with your fellow INSTAARs.


Free and open to the public.