Connected subglacial lake drainage beneath Thwaites Glacier, West Antarctica The Cryosphere DOI 10.5194/tc-11-451-2017 8 February 2017 In this paper we investigate elevation changes of Thwaites Glacier, West Antarctica, one of the main sources of excess ice discharge into the ocean. We find that in early 2013, four subglacial lakes separated by 100 km drained suddenly, discharging more than 3 km3of water under the fastest part of the glacier in less than 6 months. Concurrent ice-speed measurements show only minor changes, suggesting that ice dynamics are not strongly sensitive to changes in water flow. Read more
Snow fracture in relation to slab avalanche release: critical state for the onset of crack propagation The Cryosphere DOI 10.5194/tc-11-217-2017 27 January 2017 Based on DEM simulations we developed a new model for the onset of crack propagation in snow slab avalanche release. The model reconciles past approaches by considering the complex interplay between slab elasticity and the mechanical behavior of the weak layer including its structural collapse. The model agrees with extensive field data and can reproduce crack propagation on low-angle terrain and the decrease in critical crack length with increasing slope angle observed in numerical experiments. Read more
Refinement of the ice absorption spectrum in the visible using radiance profile measurements in Antarctic snow The Cryosphere DOI 10.5194/tc-10-2655-2016 14 November 2016 The absorption of visible light in ice is very weak but its precise value is unknown. By measuring the profile of light intensity in snow, Warren and Brand (2006) deduced that light is attenuated by a factor 2 per kilometer in pure ice at a wavelength of 400 nm. We replicated their experiment on a large number of samples and found that ice absorption is at least 10 times stronger. The paper explores various potential physical and statistical biases that could impact the experiment. Read more
Brief communication: Impacts of a developing polynya off Commonwealth Bay, East Antarctica, triggered by grounding of iceberg B09B The Cryosphere DOI 10.5194/tc-10-2603-2016 4 November 2016 Here we report new data from in situ oceanographic surveys and high-resolution ocean modelling experiments in the Commonwealth Bay region of East Antarctica, where in 2010 there was a major reconfiguration of the regional icescape due to the collision of the 97 km long iceberg B09B with the Mertz Glacier tongue. Here we compare post-calving observations with high-resolution ocean modelling which suggest that this reconfiguration has led to the development of a new polynya off Commonwealth Bay. Read more
Seasonal evolution of the effective thermal conductivity of the snow and the soil in high Arctic herb tundra at Bylot Island, Canada The Cryosphere DOI 10.5194/tc-10-2573-2016 2 November 2016 The thermal conductivity (TC) of the snow and top soil greatly impacts the permafrost energy budget. We report the first winter-long monitoring of snow and soil TC in the high Arctic. The data and field observations show the formation of a highly insulating basal depth hoar layer overlaid by a more conductive wind slab. Detailed snow physics models developed for alpine snow cannot reproduce observations because they neglect the strong upward vertical water vapor flux prevailing in Arctic snow. Read more
Ice core evidence for a 20th century increase in surface mass balance in coastal Dronning Maud Land, East Antarctica The Cryosphere DOI 10.5194/tc-10-2501-2016 25 October 2016 The reconstruction of past snow accumulation rates is crucial in the context of recent climate change and sea level rise. We measured ~ 250 years of snow accumulation using a 120 m ice core drilled in coastal East Antarctica, where such long records are very scarce. This study is the first to show an increase in snow accumulation, beginning in the 20th and particularly marked in the last 50 years, thereby confirming model predictions of increased snowfall associated with climate change. Read more
Glacier change and glacial lake outburst flood risk in the Bolivian Andes The Cryosphere DOI 10.5194/tc-10-2399-2016 20 October 2016 This is the first study of recent glacier change for the whole of the Bolivian Cordillera Oriental from 1986 to 2014. These glaciers have shrunk by ~ 43 %, which is a concern for regional water resources. We provide the first quantification of meltwater lake development across the Bolivian Andes as glaciers have receded. These lakes have increased markedly in number and area. We identify 25 lakes as potential outburst flood risks to downstream communities. These lakes require further monitoring. Read more
Quantifying ice loss in the eastern Himalayas since 1974 using declassified spy satellite imagery The Cryosphere DOI 10.5194/tc-10-2203-2016 23 September 2016 Here we utilize declassified spy satellite imagery to quantify ice volume loss of glaciers in the eastern Himalayas over approximately the last three decades. Clean-ice and debris-covered glaciers show similar magnitudes of ice loss, while calving glaciers are contributing a disproportionately large amount to total ice loss. Results highlight important physical processes affecting the ice mass budget and associated water resources in the Himalayas. Read more
Dispersion in deep polar firn driven by synoptic-scale surface pressure variability The Cryosphere DOI 10.5194/tc-10-2099-2016 15 September 2016 The upper 50–100 m of the world’s ice sheets consists of the firn layer, a porous layer of snow that is slowly compacted by overlying snow. Understanding air movement inside the firn is critical for ice core climate reconstructions. Buizert and Severinghaus identify and describe a new mechanism of firn air movement. High- and low-pressure systems force air movement in the firn that drives strong mixing, called dispersion. Dispersion is the main mechanism for air mixing in the deep firn. Read more
Sea-ice indicators of polar bear habitat The Cryosphere DOI 10.5194/tc-10-2027-2016 14 September 2016 Polar bears, found in 19 distinct regions of the Arctic, depend on sea ice as a platform for hunting. Using satellite data of sea ice for the period 1979–2014, we found that the date of sea-ice retreat in spring is arriving weeks earlier, and the date of sea-ice advance in fall is arriving weeks later, in all 19 regions. We calculated several other measures of sea ice, which all show declines. These measures were designed to be useful for management agencies to assess polar bear habitat. Read more
