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 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 Knowledge of variations in the extent and thickness of the Antarctic Ice Sheet is key for understanding the behaviour of Southern Hemisphere glaciers during the last ice age and for addressing issues involving global sea level, ocean circulation and climate change. Insight into past ice-sheet behaviour also will aid predictions of future ice-sheet stability. Here, we review terrestrial evidence for changes in ice geometry that occurred in the Ross Sea sector of Antarctica at the Last Glacial Maximum (LGM) and during subsequent deglaciation. During the LGM, a thick grounded ice sheet extended close to the continental shelf edge in the Ross Embayment. This ice reached surface elevations of more than 1000 m along the coast of the central and southern Transantarctic Mountains and Marie Byrd Land. The local LGM occurred by 18 ka on the coast, but as late as 7–10 ka inland. The first significant thinning took place at roughly 13 ka, with most ice loss happening in the Holocene. This history makes it unlikely that the Ross Sea sector was a major contributor to meltwater pulse 1A (MWP 1A). Resolution of a possible Antarctic origin for MWP 1A awaits detailed reconstructions from all sectors of the ice sheet.

Earthquakes occur in Antarctica. The previously held notion that Antarctica is essentially aseismic has been disproved by using records from established Global Seismic Network stations and recently deployed temporary stations on the Antarctic continent. However, the seismicity observed in Antarctica is very low in comparison with other continental intraplate regions. This contribution critically reviews magnitude threshold levels for recorded earthquakes and the available earthquake hypo-center data for Antarctica and the surrounding oceans. Patterns are identified in the distribution of Antarctic earthquakes and the deformation of the Antarctic plate, and the interplay between tectonic and ice-related forces controlling this distribution is discussed. In the continental intraplate region of Antarctica, earthquakes occur in three settings. Two are likely to have distributions with a tectonic control (although the level may be suppressed by ice cover)—those in the Transantarctic Mountains and scattered events in the interior. Finally, seismicity in the coastal zone and continental margin is likely to be most strongly controlled by the interaction between glacial isostatic adjustment and lithospheric thickness, with a regional tectonic component in some locations.