Abstract Near the South Pole, a large subglacial lake exists beneath the East Antarctic Ice Sheet less than 10 km from where the bed temperature is inferred to be −9°C. A thermodynamic model was used to investigate the apparent contradiction of basal water existing in the vicinity of a cold bed. Model results indicate that South Pole Lake is freezing and that neither present-day geothermal flux nor ice flow is capable of producing the necessary heat to sustain basal water at this location. We hypothesize that the lake comprises relict water formed during a different configuration of ice dynamics when significant frictional heating from ice sliding was available. Additional modelling of assumed basal sliding shows frictional heating was capable of producing the necessary heat to fill South Pole Lake. Independent evidence of englacial structures measured by airborne radar revel ice-sheet flow was more dynamic in the past. Ice sliding is estimated to have ceased between 16.8 and 10.7 ka based on an ice chronology from a nearby borehole. These findings reveal major post-Last Glacial Maximum ice-dynamic change within the interior of East Antarctica, demonstrating that the present interior ice flow is different than that under full glacial conditions.

Abstract A large volume of the East Antarctic Ice Sheet drains through the Totten Glacier (TG) and is thought to be a potential source of substantial global sea-level rise over the coming centuries. We show that the surface velocity and height of the floating part of the TG, which buttresses the grounded component, have varied substantially over two decades (1989–2011), with variations in surface height strongly anti-correlated with simulated basal melt rates ( r = 0.70, p < 0.05). Coupled glacier–ice shelf simulations confirm that ice flow and thickness respond to both basal melting of the ice shelf and grounding on bed obstacles. We conclude the observed variability of the TG is primarily ocean-driven. Ocean warming in this region will lead to enhanced ice-sheet dynamism and loss of upstream grounded ice.

Abstract The sensitivity of glacier mass balance (MB) in response to climatic perturbations has made it an important parameter of study from hydrological, climatological and glaciological point of view. To monitor the health of any glacier system, long-term MB observations are required. These observations among Himalayan glaciers are not available consistently and large glaciers are not often monitored for mass balance due to logistical challenges. One such glacier is the Gangotri, situated in the western Himalaya. In the present study an attempt is made to model the MB over the Gangotri glacier, the biggest glacier in the Ganga basin and also the point of origin of the River Ganges. The mass balance of the Gangotri glacier is estimated during the time period 1985–2014 using two different methods: ice-flow velocity; and energy balance modelling using regional model (REMO) outputs and in situ automatic weather station (AWS) data. The geodetic method is used for the nearby Dokriani glacier, where field-based MB measurements are available. MB of Gangotri glacier estimated for 2001–14 using the ice-flow velocity method is −0.92 ± 0.36 m w.e. a −1 ; for 2006–07, MB using AWS and Tropical Rainfall Monitoring Mission (TRMM) data with the energy balance modelling approach is −0.82 m w.e. a −1 ; and for 1985–2005, MB using REMO data with the energy balance modelling approach is −0.98 ± 0.23 m w.e. a −1 . Using the surface velocity method, it is estimated that the glacier lost 9% of its volume during the period 2001–14. The glacier vacated an area of 0.152 km 2 from the snout region, and retreated by 200 m in the last 14 years. MB values estimated for the Gangotri glacier from different methodologies are remarkably close, suggesting them to be suitable methods of MB estimation. TRMM, High Asia Refined (HAR-10) and Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation of water resources (APHRODITE) data are used to estimate the precipitation over the glacier. The study suggests that the glacier-wide estimation of weather parameters needs to be improved for more accurate estimation of glacier mass balance. Supplementary material: The snow-covered area, for months Jan-Dec, obtained for Gangotri glacier using Landsat data and NDSI (normalized differencing snow index) for year 2014 is available at https://doi.org/10.6084/m9.figshare.c.3888091

Abstract We describe a time series of meteorological parameters and surface energy balance components of a seasonal snow cover from an automatic weather station (4863 m a.s.l., 32.28° N, 77.58° E), for a winter season from 1 December 2012 to 30 March 2013, located on a moraine close to the equilibrium line altitude of Chhota Shigri glacier, Himachal Pradesh, India. The analysis shows that for over 80% of the time in winter, the snow surface was at a cooling phase. During late winter however, the surface had some positive residual energy which induced some melt during peak hours of the day. The net all-wave radiation was mostly negative during winter because of the high reflective property of snow and reduced incoming longwave radiation due to low cloud. The sensible heat flux heats the surface at night and enhances the cooling during day. The latent heat flux is always negative, showing that the surface is losing mass through sublimation processes (−0.83 mm w.e./day). A correlation between the energy fluxes and temperature shows a distinct relationship between fluxes. A comparison between the two studies performed on- and off-glacier reveals a significant difference in some parameters. A higher value (−1.08 mm/day) of sublimation rate at 4863 m a.s.l. shows that a large amount of energy available at the surface was used in sublimation processes. A comparatively lower albedo, relative humidity and net longwave radiation and higher latent heat flux, wind speed and net shortwave radiation yield a distinctive surface energy balance, highlighting the need for a large number of stations at different zones to achieve a coherent picture of energy balance in the region.