Abstract
ABSTRACTThe mass flux from marine terminating glacier outlets from the Greenland ice sheet is a significant mass budget term. Yet, glacier calving sensitivity to climate parameters is not well understood. In this study, the front area changes of 42 marine terminating Greenland outlet glaciers were measured annually from 1999 to 2013 using optical satellite imagery. Thirty-five glaciers retreated, while seven remained stable. The average front position change was −240 m a−1 and the total rate of front area change was −114 km2 a−1. The yearly average area changes of all measured glaciers are compared with interannual variations in sea surface temperature (SST), sea-ice concentration (SIC), surface melt, Northern Hemisphere (NH) surface air temperatures and the North Atlantic Oscillation (NAO) index. We find: (1) northwestern glaciers area change have a significant correlation with surface melt and NH land temperature variations; (2) southeastern glaciers have a significant correlation with local SST, SIC and NH temperatures; and (3) southwestern glaciers area change correlate significantly with local SST and NAO index. We conclude that a climate sensitivity signal emerges considering a population of glaciers. Further, we find a significant correlation between the date of minimum extent and glacier latitude. Area change data are available from http://GAC.geus.dk.
Highlights
The Greenland ice sheet has been losing mass in recent decades in response to climate warming (AMAP, 2009)
The Daugaard-Jensen is here grouped with the SE glaciers though it is located much further from the sea than the other SE glaciers since the alternative would be to group it with the NE glaciers, which are all outlets from the East Greenland Ice Stream
A significant correlation of −0.52 was found between ΔAnet of each glacier and its latitude indicating that the glaciers further north generally have larger area changes than the southern glaciers
Summary
The Greenland ice sheet has been losing mass in recent decades in response to climate warming (AMAP, 2009). Marine terminating glaciers are found to respond dynamically to retreat at the front by thinning and accelerating, since the flow resistance of the glacier is reduced (e.g. Howat and others, 2007; Moon and Joughin, 2008). The observed retreat of the glacier fronts is thought to be a result of the warming climate (Murray and others, 2010; Andresen and others, 2012; Carr and others, 2013) and marine terminating glaciers are expected to respond quickly to changes in the regional climate due to dynamic processes (Moon and Joughin, 2008). Where meltwater reaches the glacier bed, flow speed will increase due to hydraulic lubrication resulting in dynamic thinning at least until an effective drainage system develops, but the response of ice motion to seasonal surface melt on interannual timescales is uncertain (e.g. Zwally and others, 2002; Shepherd and others, 2009; Bartholomew and others, 2010). Measuring polygon area instead of changes along a central flow line accounts for uneven front shape changes
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 call
