Abstract
Abstract. In consideration of the strong atmospheric warming that has been observed since the 1990s in polar regions there is a need to quantify mass loss of Arctic ice caps and glaciers and their contribution to sea level rise. In polar regions a large part of glacier ablation is through calving of tidewater glaciers driven by ice velocities and their variations. The Svalbard region is characterized by glaciers with rapid dynamic fluctuations of different types, including irreversible adjustments of calving fronts to a changing mass balance and reversible, surge-type activities. For large areas, however, we do not have much past and current information on glacier dynamic fluctuations. Recently, through frequent monitoring based on repeat optical and synthetic aperture radar (SAR) satellite data, a number of zones of velocity increases have been observed at formerly slow-flowing calving fronts on Svalbard. Here we present the dynamic evolution of the southern lobe of Stonebreen on Edgeøya. We observe a slowly steady retreat of the glacier front from 1971 until 2011, followed by a strong increase in ice surface velocity along with a decrease of volume and frontal extension since 2012. The considerable losses in ice thickness could have made the tide-water calving glacier, which is grounded below sea level some 6 km inland from the 2014 front, more sensitive to surface meltwater reaching its bed and/or warm ocean water increasing frontal ablation with subsequent strong multi-annual ice-flow acceleration.
Highlights
Mass loss from glaciers and ice sheets contributes about one third to current sea level rise (Church et al, 2013)
Glacier elevation changes were computed between the NPI digital elevation models (DEMs) of 1970 and the Intermediate DEM (IDEM) of 2010/2012, and the IDEM and the ASTER DEM of 2014, and are presented in Fig. 3a and b, respectively
Between 2010/2012 and 2014 we observe over an area of about 15 km2 in the inland of Stonebreen ice surface losses of 50 to 70 m
Summary
Mass loss from glaciers and ice sheets contributes about one third to current sea level rise (Church et al, 2013). The total calving flux of Svalbard is dominated by a few large and fastflowing glaciers (Dowdeswell et al, 2008), and variations in their speed can have large influence on the total mass balance of the archipelago’s glaciers. A few glaciers, such as Kronebreen and Kongsbreen near Ny Ålesund, western Spitsbergen, are continuously fast-flowing, with maximum speed of more than 2–3 m d−1 at the calving front. These glaciers show seasonal variations in speed related to meltwater input to the glacier base (Dunse et al, 2012; Schellenberger et al, 2015). At least, decades such calving front retreats are typically irre-
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