Abstract
AbstractUpernavik Isstrøm, a marine glacier undergoing rapid retreat, is simulated by forcing a numerical model with ocean-driven melt. A review of processes driving retreat led us to hypothesize that a glacier undergoing rapid retreat may be less sensitive to perturbations in the balance of forces than a glacier that is undergoing moderate changes or a glacier in steady state. Numerical experiments suggest this is not the case, and that a system in rapid retreat is as sensitive to basal traction perturbations as a system that is near to steady state. This result is important when considering other glacier systems experiencing marine-forced retreat. While the ice–ocean interface is of primary importance, additional perturbations from meltwater-forced decoupling of the glacier from its bed continue to feature in glacier dynamics.
Highlights
Along with surface runoff, discharge from marine-terminating outlet glaciers is a primary cause of ice mass loss from the Greenland ice sheet
Upernavik Isstrøm loses a maximum of ∼150 Gt of mass over 50 years (Figs 2a, d), and both subaqueous melting and basal traction perturbations are important for determining total mass loss (Fig. 2c)
For the maximum tested subaqueous melt rate of 2.4 m d−1 and a basal traction coefficient reduction of 40%, Upernavik Isstrøm loses over 500 Gt of ice, which is ∼0.06% of its steady-state mass (Fig. 2a)
Summary
Discharge from marine-terminating outlet glaciers is a primary cause of ice mass loss from the Greenland ice sheet (van den Broeke and others, 2009; McMillan and others, 2016). Fast-flowing tidewater glaciers transport volumes of ice from cold, inland regions to warmer coastal areas where it is lost to surface melting submarine melting, and calving (Vieli and Nick, 2011; Truffer and Motyka, 2016). Increasing atmospheric and ocean temperatures have been linked to rapid changes in outlet glaciers including flow acceleration, thinning and rapid retreat (Holland and others, 2008; Moon and others, 2012). Mechanisms responsible for retreat include increased subaqueous melting caused by intrusion of warm Atlantic waters into fjords (Holland and others, 2008; Rignot and others, 2010; Motyka and others, 2011) and turbulent heat exchange at the ice–ocean interface from subglacial discharge (Xu and others, 2012; Truffer and Motyka, 2016). Submarine melt plays an important role in controlling the dynamics of large, marine-terminating glaciers such as Petermann Glacier and Jakobshavn Isbræ in Greenland and Pine Island Glacier in Antarctica (Holland and others, 2008; Jacobs and others, 2011; Nick and others, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
